Friday, December 23, 2005


Page et al. find that broad-lined z~2 QSOs with X-ray absorption are embedded in submillimeter luminous starbursts implying that the X-ray absorption is unrelated to the AGN torus.

Balogh et al. compare analytical models of the ICM with recent observations and find that a range of entropy floors are required at a given halo mass.

Ho et al. use large-scale simulations to study cluster ellipticity as a cosmological probe and conclude that it provides another route to constraining cosmological parameters from large cluster samples.

Fang et al. argue that the z~0 absorbers seen in high resolution spectra of AGN are due to the hot gas associated with the Galaxy.

Sorkin republishes an old paper using Bayesian methods to derive a goodness-of-fit balancing likelihood against the number of fitting parameters.

Belczynski et al. describe the StarTrack population synthesis code for the formation and evolution of compact objects.

Dunn et al. discuss the behaviour of rising bubbles in the ICM and the precession of the 3C 84 jets in the Perseus clusters.

Thursday, December 22, 2005


Crummy et al. fit XMM spectra from a sample of SyI with a relativistically-blurred photoionized disc and find this model reproduces the continuum shape, including the soft excess and many features usually interpreted as absorption, in all sources.

Fabbiano reviews X-ray source populations in galaxies.

Vernaleo & Reynolds perform 3-D hydro simulations of jets in the ICM and find that the jet energy input cannot halt the cooling flow because the energy is transmitted out of the cooling region along a low-density channel.

Sun et al. observe a 70 kpc tail behind a late-type galaxy in A3627 and use this to place constraints on turbulence in the ICM.

Jahoda et al. summarize the RXTE PCA calibration.

Hamilton et al. use archival WFPC2 imaging of 70 QSOs to find a relation between nuclear luminosity and the size and effective surface magnitude of the bulge.

Bridges et al. present a Bayesian analysis of the primordial power-law spectrum.

Baker et al. present new numerical GR techniques which enable accurate determination of GW signal from merging BHs.

Hughes motivates the widespread acceptance of BHs and describes planned tests of the hypothesis.

Nath et al. consider the production of Li6 by spallation of cosmic rays on ambient gas and show that the amount of energy generated is consistent with the extra entropy seen in the ICM.

Agueros et al. cross-correlate the RASS and SDSS looking for X-ray sources with no optical counterparts as a way of searching for isolated NS.

Cappi et al. present the results from a complete XMM survey of nearby AGN and find results broadly in agreement with the standard unified model.

Wednesday, December 21, 2005


Bregman shows that a claimed relationship between radio, X-ray luminosity, and BH mass in AGN is an artefact of the flux-limited sample.

Armus et al. find evidence with Spitzer for an AGN in NGC 6240 - consistent with the hard X-ray results.

Stuhlinger et al. summarize the status of XMM-Newton calibration.

Donahue et al. present Chandra entropy profiles of 9 cooling flow clusters and find the profiles are similar over a range of 3 in temperature.

Ghizzardi et al. find cold fronts in 21 out of 62 clusters searched using XMM data.

Monday, December 19, 2005


Badenes et al. compare the XMM and Chandra observations of Tycho with detailed hydro calculations of a variety of proposed models for SNIa and find the observations are consistent with a 1-D delayed detonation model.

Weinberg discusses multiverses and anthropic arguments.

Mathews et al. show that spherical shock waves in the ICM dissipate most of their energy near the center of the cluster causing temperatures higher than observed hence are not good candidates for solving the cooling flow problem.

Henry et al. present the results from the complete ROSAT NEP survey.

Haehnelt et al. suggest that the bright QSO HE0450 which has no detected galaxy is an SMBH ejected from its galaxy during a merger. However Merritt et al. argue against this since the kick velocity required is too large and claim that previous observations have overestimated the size of the SMBH and hence the expected luminosity of the underlying galaxy.

Bregman et al. summarize their results of OVI observations of 24 galaxies using FUSE. They find a correlation between the cooling flow rate from OVI and that from X-rays but with a large scatter. The cause of the scatter is not clear but is not obviously due to heating.

Weisskopf & Hughes give an overview of the first 6 years of Chandra observations of SNR.

Friday, December 16, 2005


Kim et al. combine Chandra and HST data to examine the relationship between LMXBs and Globular Clusters in 6 Elliptical galaxies. They confirm that the probability of a GC containing a LMXB correlates with metallicity and also find a correlation with galactocentric distance.

Dravins et al. discuss the design of an optical instrument designed to search for variability on nanosecond scales and planned for the 100m-class OWL telescope.

Kashlinsky et al. use fluctuations in the background of a deep Spitzer observation to find evidence for Pop III stars.

Thursday, December 15, 2005


Noble et al. describe parallelizing ISIS using the PVM.

Chevallier et al. discuss the relative roles of absorption and reflection in low energy X-ray spectra of AGN.

Belczynski et al. calculates the contribution to the LISA signal from mass transferring binaries.

Hallman et al. present calculations of H_0 based on X-ray/SZE observations of clusters assuming a universal temperature profile. This gives H_0 values closer to the standard and with smaller variance.

Blustin et al. do principle component analysis of the X-ray variability of NGC 7469.

seg fault in pexrav

Roderick Johnstone reported a seg fault in pexrav when running on a 64 bit Athlon. Craig spotted a problem on the first invocation of the model in the routine sigmabfa. There was a similar bug in pexriv, bexrav, and ntee which all use copies of this routine. At some point I need to rationalize all these programs and remove duplicated routines. Fixed as v11.3.2r and 12.2.1i & j.

Keywords: HEAsoft, xspec

Thursday, December 08, 2005

xselect manual

Updated the manual available on the web. Did the LaTeX and HTML conversion on genji in TEXT/XSELECT then copied to olegacy. Note that latex2html makes an xsel.tex top-level file. Copy that to xselect.html, remove all the contents links and tidy up. Add the contents links to node1.html. Change references in several files from xsel.tex to xselect.tex.

Keywords: HEAsoft, xselect

Thursday, December 01, 2005


Gastaldello et al. analyze Chandra and XMM observations of poor clusters and find cool cores, a peak in temperature around 0.1 virial radii and decline. NFW model fits give concentration parameters and virial masses consistent with numerical simulations.

Done & Gierlinski show that an apparent highly relativistic line in XTE J1650 can be modelled by a relativistic line and Fe K line absorption from an outflowing disk wind - this allows the inner disk to be truncated.

Dave et al. provide an overview of current issues in galaxy formation theory.

HEAsoft 6.0.4

HEAsoft 6.0.4 is now available. This is an update for Swift but also includes XSPEC v12.2.1 and
changes to cleansis and xselect/extractor for Suzaku.

Wednesday, November 30, 2005


Morganti et al. detect 1000 km/s outflows of neutral material from seven radio galaxies. This rate of up to 50 Msun/yr is comparable to outflow rates from ULIRGs.

Aharonian et al. suggest a possible associate between HESS J1825 and the pulsar wind nebula of PSR B1823 based on XMM observations of the latter.

Kauffmann et al. look at the scatter in colours and spectral line strengths of local galaxies and deduce that star formation in more compact galaxies occurs in high amplitude bursts.

Fabian et al. present first results from the 1Msec Chandra Perseus cluster observation. The pressure ripples observed in shorter observations are shown to be isothermal sound waves that can provide a heat source able to balance radiative cooling.

Chen & Pradhan calculate the ratio of the FeXVII 3s/3d lines using different electron distribution functions and surmise that some of the differences between astrophysical and laboratory measurements may be due to different plasma conditions.

Monday, November 28, 2005

extractor rotated box regions

My fix to the elliptical regions back in July broke the rotated box regions. The subroutines for boxes and ellipses define the rotation angle in the opposite sense. Now fixed so that both are correct (v4.61).

Keywords: HEAsoft, extractor

Thursday, November 17, 2005

xselect bug causing wrong date on lightcurve plots

The values of MJDREFI/F were not propagated everywhere correctly. I think the only consequence was that the label written at the top of the lightcurve plots gave the delta MJD not the MJD. Also did some reorganising of code and split the clear functions out into their own file (xsel_clear.f).

Keywords: HEAsoft, xselect

Monday, November 14, 2005


Wyse & Gilmore review the Galactic populations of long-lived stars and how they can be used to investigate chemical and dynamical evolution.

Wolter et al. find three high-luminosity, narrow-line objects (ie QSO2) in the ROSAT NEP region which XMM spectra show to have no absorption above Galactic.

Revnivtsev et al. analyze RXTE scan and slew observations of the Galactic ridge X-ray emission and show that the intensity correlates with the near-infrared surface brightness and hence that the ridge emission is likely made up of many low luminosity point sources.

O'Hara et al. examine the effects of cool-cores and mergers on cluster scaling relations. They suggest that effects of cool-cores can be seen outside the cores themselves indicating that global mechanisms are at work. The evidence does not support the scenario that clusters develop cool-cores till disrupted by mergers.

Plaszczynski et al. present a fast algorithm for generating 1/f^alpha noise by filtering a white noise signal.

Liedahl & Torres provide a tutorial summary of Fe K line emission from accretion disks.

Lieu et al. claim that by comparing a WMAP and X-ray observations of a randomly-selected sample of 20 nearby clusters that the observed SZE effect is not as large as predicted.

Goad et al. describe deep XMM observations of the ULX HoII X-1 and conclude it is a high-luminosity analog of a Galactic microquasar.

Kontar et al. calculate angle-dependent Green's functions for the Compton reflection problem in Solar flares.

Thursday, November 10, 2005

new models added to xspec v12

I've added Martin Still's dust extinction models and Slava Zavlin and George Pavlov's NS atmosphere model to the xspec v12 for the forthcoming release. When the release is out I will retire them from the additional models webpage.

Keywords: HEAsoft, xspec

Sunday, November 06, 2005

PLT command lengths in xspec v11

Bill ran into a problem running the Swift processing script under Hera. He needed to create a gif file in xspec v11 in a remote directory with a long pathname. This overran the string length available in xspec. Modified xspec to allow longer PLT command names and device names. I also had to modify PLT to increase the allowed device name length. The limit now is 80 characters which seems to be imposed by the PGPLOT code. I've not tried to track down where that is set.

Saturday, November 05, 2005

Theatre: Cuttin' Up

Last night went to Arena stage for the first night preview of world premiere. Cuttin' Up is written and directed by Charles Randolph-Wright adapted from the book of the same name by Craig Marberry, who visited African-American barbershops around the US collecting the stories told there. The barbershop and the church are the two places African-American men can gather and talk and a rich history has built up around the former. The play presents that history as stories told by the three barbers and their customers, all of whom are played five actors in a wide variety of wigs. Dramatic tension is supplied by the conflict between the owner and the man he wants to be his successor, but who has a history of leaving cities and marriages. I found the story suprisingly effective since it is little more than a rack on which to hang a wonderful collection of vignettes and songs. Among the former my favourite was a competition between a Baptist and an AME preacher. The Baptist played by Bill Grimmette finished with a peroration on the importance of the barbershop delivered in full sermon style.

The show was almost stolen by Marva Hicks playing all the female characters from hot youngster, through mother from the projects, R&B singer, outrageously-dressed Texan female barber, to the 75-year-old mother of one of the barbers. She and many other cast members pulled off some very fast changes, both of clothes and hair styles. The other star of the show is the costume department with their wonderful collection of wigs all the way up to a 2-ft wide Afro.

With an almost full house for first-night preview and a standing ovation at the end this one will be a hit for Arena.

Thursday, November 03, 2005

chkrmf fix

Fixed infinite loop which arises if one of the extensions doesn't have its EXTNAME set. Also replaced explicit loop through extensions with calls to go to named extensions. Note that this program and its peers (chkarf, chkpha) could do with an overhaul and check for consistency with the current standard.

Keywords: HEAsoft

minor extractor bug with multiple event files

There was an error in the code comparing TLMIN/MAX values for WMAP columns when reading multiple event files. This produced a spurious warning message about different sizes for XCOLH and YCOLH columns. Fixed in v4.60.

Keywords: HEAsoft, extractor

Monday, October 31, 2005


Li-Xin Li & Paczynski present a new procedure for smoothing GRB lightcurves and calculating the variability. This leads to a very tight correlation between variability and peak luminosity.

Muanwong et al. use hydro simulations to investigate the evolution of X-ray cluster scaling relations under different mechanisms to increasing the entropy. They find indications that early, widespread pre-heating is favoured.

Dotti et al. study the inspiral of binary black holes inside a massive circum-nuclear disk.

Markwardt et al. present the first BAT serendipitous source catalog. The final catalog is expected to contain > 200 AGN and reach a limiting flux of 1e-11 in the 14-195 keV band.

Brewer & Lewis use Bayesian Inference and MCMC simulations on the strong gravitational lens problem.

Regimbau & Pacheco estimate the gravitational background from magnetars and note that it could mask a contribution from the early Universe.

Thursday, October 27, 2005


Dewangan et al. report the detection of a low frequency break and a QPO in the ULX M82 X-1. This is characteristic of an XRB in a high or intermediate state. The BH mass is estimated at 50-260 Solar masses.

Peterson et al. take a sample of nearby well-studied AGN and artificially redshift them to z=0.3 then consider what would be seen in a Chandra survey. They argue that these objects look like the "normal" and "optically-bright X-ray-faint" galaxy populations suggesting that these objects may contribute to the hard X-ray background.


Cappi et al. present the results of an XMM survey of the nearest 27 Seyfert galaxies. The results are broadly in agreement with unification models with Sy 2 absorption columns ranging from 1e20 to 1e25 cm^-2.

Zhao et al. apply Bekenstein's relativistic version of MOND to gravitationa lens observations. They find a range of acceleration scales are required in violation of the assumption that this is a universal constant.

Lu & Love present a method for diverting an Earth-threatening asteroid using a spacecraft that hovers near the object. This eliminates the anchoring and rotation problems of a spacecraft pushing on the asteroid.

Diehl & Statler analyze archival Chandra observations of 30 early-type galaxies and find a relation between the X-ray temperature, half-light radius, and mean surface brightness. The width of this fundamental plane (0.07dex) is nearly identical to that of the stellar (optical) fundamental plane.

Atoyan et al. argue that HESS J1303-631, a bright, extended TeV source invisible at other wavelengths is the remnant of a long gamma-ray burst.

Stroeer et al. discuss what can be learned from LISA detections of interacting double WD binaries.

Seward et al. find no evidence for a thermal shell around the Crab Nebula from Chandra observations. The background consists of a dust scattering shell and mirror scattering.
The shell has L_X < 1e34 erg/s.

Watson et al. present the Swift X-ray spectrum and lightcurve of the z=6.29 GRB. In the first few minutes of the burst the apparent luminosity was 1e5-1e6 times that of the brightest high-z quasars.

Sunday, October 23, 2005

xselect bug causing deletion of event files !

There is a bug in xselect which causes an event file to be deleted when running a make obscat for a mission with > 8 instrument types. This is triggered for the Suzaku HXD. I've fixed this by increasing the allowed number of types to 20 and putting in a trap to catch any future case of more than this. Also added DETNAM to the HXD displayed values so that the user can see which files in the catalog are PIN and which GSO.

Keywords: xselect, Suzaku

Saturday, October 22, 2005

CHANNEL column in type II files

At the request of the GLAST GBM folks removed the requirement for a CHANNEL column in type II spectral files. Having the CHANNEL column vector in every row is inefficient when there are many rows and the information is not required as long as data from all spectral channels are included in the COUNTS or RATE vector. Available as v11.3.2p and also shortly in v12. Need to update the standard memo appropriately.

Keywords: HEAsoft, xspec, GLAST

Wednesday, October 19, 2005

bug in extractor when combining 3x3 and 5x5 XIS files

Aya Bamba reported an obscure bug when running extract event in xselect. If both 3x3 and 5x5 event files are in use and the 5x5 is first then the resulting event file loses the events from the 3x3 file. Reproducing her problem showed that the events from the 3x3 file were in the output file but their TIME column had zero values. This was due to a bug in extractor which occurred if the first file had fewer columns than the second - the values from the extra columns would be lost even if these columns were matched in name with those in the first file ie if the differences between the files consisted of some additional columns added in the middle of the row. This
particular case has probably never arisen before. Fixed as extractor v4.59.

Keywords: HEAsoft, xselect, extractor, Suzaku

Thursday, October 13, 2005

extractor and region files

Extractor seg faults when fed a region file with a comment marker (#) included after a region descriptor. This can happen if a color is specified for the region using ds9.

Keywords: heasoft, extractor

Monday, October 10, 2005

grppha and grouping=0

Fixed grppha so that individual bad channels have grouping=1 not grouping=0. This conforms with the standard and ensures that xspec v12 doesn't issue a warning. This should not change any other behaviour.

Keywords: HEAsoft

Tuesday, October 04, 2005

xselect/extractor updates

A couple of minor updates. In extractor trapped the case of the grade column having no TLMIN/MAX. Previously this generated an obscure error when running. Now arbitrarily assumes that grade varies between 0 and 25. This should be fine as long as the actual grade is within this range. Also updated xselect.par so that the default mission is Suzaku rather than ASCA (about time!).

Keywords: HEAsoft, xselect, extractor

Monday, October 03, 2005

Suzaku XIS sky images

The current v0.1 processed files have sky image coordinates wrong due to an error in xiscoord. To get correct positions either multiply the image CDELT1 and CDELT2 by -1 or in the event files set TCDLT10 = 0.0002895 and TCDLT11 = -0.0002895.

Keywords : Suzaku

Tuesday, September 20, 2005


Gregory performs a Bayesian analysis of extrasolar planet data for HD 208487.

Hallman et al. use synthetic observations of numerical observations of clusters to determine the limits on precision cosmology using cluster mass measurements.

Sunday, September 18, 2005


Fixed cleansis so that it looks for the EVENTS extension not just the first extension. This ensures it works on Suzaku SFF files. Also cleaned up a lot of unused variables.

Keywords: heasoft, Suzaku

Wednesday, September 14, 2005

v11 bug when using cstat with background

Jeremy Sanders reported that using cstat with background generated a NaN fit statistic value when running on an x86_64. Turned out to be a function that was not defined as double precision in the calling routine. Fixed as 11.3.2o.

Keywords: xspec

More on xselect for Suzaku HXD

The HXD consists of two parts - the PIN and GSO. We have a separate event file for each part with the difference in keywords being DETNAM='WELL_PIN' for the former and WELL_GSO for the latter. The PIN uses PI_PIN for spectra and the GSO PI_SLOW. To handle this in xselect I set the dmodekey for HXD to DETNAM and then have WELL_PIN and WELL_GSO as the modes. The prelaunch xselect.mdb rebinned output spectra. I removed this since the example RMFs do not require it.

There was an error in xsel_read.f which implicitly assumed that dmodekey was the same for all instruments in a mission. This is fixed but will require users to patch. Using only the release version of xselect the user will have to do a set phaname to PI_PIN or PI_SLOW as appropriate.

Also did some tidying up of the (t)xselect.key file which contained some incorrect parameter names leading to warning messages when using the lparm command.

Keywords : xselect, Suzaku

Friday, September 09, 2005

Suzaku and xselect

More changes to xselect.mdb for Suzaku XIS. Corrected name and location of common HK file, changed autobinning to 8 for image and wmap, changed save spectrum behaviour so no binning is performed but only channels 0 to 4095 are output - this matches AO1 response matrix. Set chip column to SEGMENT to allow sisclean command to work using updated cleansis tool. Note that
this also means that ccol will be set to SEGMENT on running extractor. I don't think this will have any effect but watch out for any problems. Changed Suzaku XIS instrument names from XIS-# to XIS# since the latter is what the INSTRUMENT keyword is set to in the event files.
Changed lststr so make cat finds only the event files in the xis directory.

Created web page on using xselect for Suzaku. Included links to new versions of cleansis.f and xselect.mdb.

Keywords: heasoft, xselect, Suzaku

Wednesday, September 07, 2005


Aharonian et al. report on the HESS detection of >100 GeV photons from a candidate microquasar.

Shafee et al. estimate the BH spin for a couple of XRBs using spectral fits to the contiuum.

Kawanaka et al. calculate Fe line profiles from coronae heated by magnetic reconnection.

Page et al. summarize XMM observations of 29 quasars at z > 2. No Fe lines or reflection humps are observed.

Dupuis & Woan present a method of searching for GW signals from known radio pulsars.

Qin et al. argue that the flat cores in dark matter haloes could be explained if there are 3 large extra dimensions of nm size.

Donahue et al. present Chandra observations of two cool core clusters with no evidence for a central AGN. They find no cavities, no central temperature gradients, and a higher entropy than other cores. One explanation is a major heating event ~1 Gyr ago.

Chandra and xselect

Modified xsl_chandra_acis_makeresp to hand mkacisrmf the correct required parameters. This should ensure the response-generation option in xselect works correctly with versions of CIAO 3.2 and later.

UPDATE: Didn't get this quite right. Note that the wmap parameter should just be the spectrum file. I had it still as the weights file output by mkwarf. This caused mkacisrmf to fail silently.

Keywords: heasoft, Chandra

Suzaku XIS and xselect/extractor

Added a line to xselect.mdb to set gcol to GRADE so that the filter grade option can be used on XIS event files. This also requires the TLMIN/MAX for the GRADE column to be set in the input files which is not the case yet.

Fujimoto-san pointed out that extractor doesn't work correctly if the input event file has no GTIs and there are selection GTIs set (eg from select hk). The resulting event file has no events but does have GTIs and hence non-zero exposure time. This is fixed in extractor v4.56.

Keywords : heasoft, Suzaku

Thursday, September 01, 2005


Fujita & Suzuki show that heating of cluster cores by sound waves combined with thermal conduction from the outer regions can reproduce the X-ray observations of cooling flows.

Gebhardt et al. use new Keck and HST data to argue the correctness of their 2002 claim that the globular cluster G1 contains a 1e4 Solar mass BH.

Dhurandhar et al. present a model of the LISA spacecraft constellation.

Prochaska et al. present echelle spectroscopic results from GRB050730 at z=3.969 and obtain extensive diagnostics on the ISM of the host galaxy including its metallicity at 0.01 Solar.

Gair et al. give new more accurate expressions for the energy and angular momentum lost by a compact object during a parabolic encounter with a non-spinning BH.


Pradas & Kerp study the effects of proton flares on XMM EPIC MOS and PN detectors. The find an unreported soft (<0.5 keV) additional background in MOS1.

Hicks & Mushotzky analyze XMM OM data from a sample of 33 galaxies and find a significant UV excess in many central galaxies in cooling flow clusters.

Chluba & Sunyaev point out that induced emission of the softer photon slightly increases the two-photon decay rate of the 2s level of hydrogen. This is important for calculations of cosmological reionization and changes CMB temperature and polarization anisotropies.

Hilton et al. cross-correlate the 2dFGRS and REFLEX.

Gallo et al. find a possible line-like emission feature at 8 keV in an XMM spectrum of a Sy 1.2.

Kirsch et al. give the results of XMM observations of the Crab and discuss its use as an X-ray calibrator.

Kirsch et al. present trend data for the XMM EPIC detectors.

extractor with region files created under Windows

For Hera Bill needs extractor to behave correctly with region files created on a Windows machine. They have LF and CR at the end of each line so regions.f was modified to strip off any extraneous CR. This shouldn't change any other behaviour.

Keywords: heasoft, extractor, Hera

Wednesday, August 31, 2005

gfortran/g95 and xspec

A few changes to run under the new gfortran (with gcc 4). In grad.f replace IMAG function with AIMAG. This should make no difference and AIMAG is the f90 standard. In calcml.f make sure that both arguments to SIGN are double precision.

Keywords: xspec, g95

long log filenames in xspec v11

Jeremy Sanders reported hitting occasional seg faults when using long log filenames. He traced this to an 80 char fixed length string in tcllog.c. I've increased this to 1024 chars. v11.3.2n.

Keywords: xspec

Tuesday, August 30, 2005


Cleansis assumes that chips are square. However, the individual segments in the XIS are rectangular (4x as long in the RAWY direction as RAWX). So I modified cleansis to use internal image arrays set by the maximum of the RAWX and RAWY sizes. This is slightly inefficient use of memory but much easier than changing the program to use non-square internal images.

Keywords: heasoft, Suzaku, XIS

Wednesday, August 03, 2005


Adami et al. identify 17 groups in the Coma cluster by combining X-ray and galaxy redshift information.

Wittman et al. present first results from their cluster survey based on weak lensing.

Peterson et al. propose a new inference method for the ICM describing clusters as a collection of smoothed plasma particles with temperature, location, size, and abundances. X-ray data are predicted and iterated using MCMC.

Croton et al. investigate the growth of galaxies and SMBH using semi-analytic models on top of very large LCDM simulations.


Finished the upgrade to genrsp (at least for the moment). Now v2.0. The major changes are
  1. Response energies and channel definitions can now be read from input (ascii) files. This required adding new parameters resp_reln, resp_file, chan_reln, chan_file.
  2. If the response energies and/or channel definitions are not read from the file then the parameters to define them have been altered to set the number of energies/channels rather than their size. This will allow an extension to logarithmic intervals at some time in the future.
  3. The response energy parameter names now all start resp_. To avoid possible confusion the resolution parameters res_reln and res_file have been renamed to resol_reln and resol_file
  4. The resol_file input file format has been altered to allow multiple response peaks. genrsp can now build a response with multiple gaussian peaks from a given input energy (eg photopeak and escapes). At present the input file is ascii but a FITS format will be supported when a standard has been defined.

Friday, July 22, 2005


Boehringer et al. find a massive cooling flow cluster RXCJ1504.1-0248 with a central giant elliptical hosting a known radio source.

Pope et al. investigate the effects of thermal conduction on the ICM using a 3-d model of the Virgo cluster. They find little effect for any physically reasonable values of the conduction.

Finoguenov et al. study the 2-D structure of the nearly volume- limited subset of REFLEX clusters at z~0.3.

Glazebrook et al. summarize a proposed Gemini/Subaru wide field redshift survey with the goal of measuring the baryon oscillations using 2.6 million galaxies.

Warren et al. present evidence from Chandra that cosmic ray acceleration is occurring at the Tycho forward shock.

Bocchino et al. argue that G21.5 X-ray halo can be described as dust scattering from the plerion, particle acceleration in the fast forward shock, and a bright spot which may be ejecta in adiabatic expansion.

Thursday, July 21, 2005


Added an arfcol hidden parameter option to allow the user to specify a column other than SPECRESP from which to read the ARF data. This increases flexibility and may be useful for Suzaku if we end up creating ARF files with an individual column for each pixel.

Keywords: heasoft, suzaku

Wednesday, July 20, 2005

Suzaku and xselect

Added a SUZAKU mission to xselect.mdb. Also switched catnum from 0 to 1 since the primary header doesn't appear to contain the descriptive keywords.

Set ccol to PIXEL to ensure that DSS keywords are updated when region filtering. Note that this requires the input event files to have the DSS keywords for PIXEL set up with one keyword per pixel eg DSTYP1='PIXEL', DSVAL1='0:0', 2DSVAL1='1:1',...,32DSVAL1='31:31'. Only one time DSS keyword set is required however (DSTYP2='TIME', DSVAL2='TABLE', DSREF2=':GTI') unless at some point we require separate GTI extensions for each pixel.

With these changes it is now possible to select pixels either by FILTER COLUMN with the argument eg PIXEL=0:5 10:12 or by the standard region filtering which will include all pixels with an events included in the (X,Y) region.

Keywords : heasoft, xselect, Suzaku

Monday, July 18, 2005

Plotting more than 15 spectra in xspec

Steve Snowden pointed out that with > 15 spectra read in then spectrum 16 and above are not plotted. This occurs because PGPLOT only defines 15 colours so PLT commands of the form
COLOR 16 ON N generate a black line on black background. The fix is to cycle round the colours
so spectrum 16 is plotted with colour 1 and so on. This is 11.3.2l and will appear shortly as a patch to v12.

Keywords: heasoft, xspec

Thursday, July 14, 2005

xselect/extractor region rotation angles

Fixed inconsistency between rotation angle defined in ds9 ELLIPSE and BOX regions and their use in extractor. It appears that extractor was treating these angles as clockwise from the x-axis while ds9 defines the angles as counter-clockwise from the same axis. This fix is extractor v4.55 (14 Jul 2005).


Pat Broos reported a discontinuity in Cstat when running under Solaris with a very weak source and background. Craig spotted this as round-off error when solving the quadratic in the case where b^2 >> ac. Fixed this using the algorithm from NR. Also explicitly handled the special cases of zero source or background counts in a channel. I don't think this latter changed any results.

Note that in the very weak source limit Cstat appears to exhibit bias in some circumstances ie the best fit does not appear to be correct when doing a plot icounts. Cstat with background is a profile likelihood which is well known in the statistics literature to exhibit bias in the low sample limit. A practical partial solution appears to be to run grppha with group min 1 to ensure that every bin has at least one count. The statistics literature does offer corrections to the profile likelihood but these appear to be algebraically very complex in this case.

Tuesday, July 12, 2005


Kleyna et al. estimate the mass of the newly discovered extremely low luminosity Ursa Major dwarf spheroidal and find central M/L ~ 500. They theorize that this could be an example of the missing low mass haloes that standard cosmology predicts should surround our Galaxy.

Frontera et al. review the prospects for imaging in the 60-600 keV band using Laue lenses.

Ebisawa et al. present the results of a deep Chandra observation of the Galactic plane with follow-up IR imaging. They also study the spectrum of the diffuse X-ray emission.

Thursday, July 07, 2005


Lehmer et al. present sources in the CDFS flanking fields.

Alexander et al. show that 75% of the SCUBA sources in the CDFN harbor AGN.

Kino & Kawakatu use the cocoon to estimate the kinetic power and age of Cygnus-A.

Famaey & Binney argue that inner Milky Way dynamics excludes Bekenstein's covariant gravity formulation of MOND.

Haiman et al. describe using a 100,000 cluster X-ray survey to place constraints on Dark Energy.

Canizares et al. describe the Chandra HETG and its in-flight performance.

Heinz & Churazov argue that bubbles of relativistic gas in the ICM act as catalysts converting sound and shock waves to heat.

Crotts et al. present a white paper proposal for JEDI, a 2m space telescope with wide-field imaging and multi-slit spectroscopy capable of doing SNIa, baryon oscillation, and weak lensing studies.

Vikhlinin et al. analyze Chandra data on 13 nearby clusters and derive temperature and density profiles out to large radii. f_gas profiles don't reach Universal values till r > r_2500.

Thursday, June 30, 2005

Repeated WENV in PLT

Allyn Tennant supplied a fix to a problem noted by Tahir Yaqoob that repeated use of WENV in PLT ended up producing a message about exceeding the available unit numbers.

Note that headas has too copies of qdp & plt, one under ftools and the other under Xspec/plot. I don't think this duplication is necessary. The ftools copy is two years and the Xspec copy is four years out-of-date.

Allyn now has a QDP/PLT webpage with the latest version available by ftp.

Tuesday, June 28, 2005


The Jan 05 fix to the kerrbb new model didn't make it into the recent release. Fixed this as
11.3.2j and will also appear shortly as a v12 patch.

Sunday, June 26, 2005


Wyithe & Loeb argue that SMBH growth rate is determined by the spheroid velocity dispersion, not the mass.

Cornish & Crowder test MCMC methods for LISA data analysis.

Bertolami & Vieira test various models of the Kuiper belt to see whether they can explain the Pioneer Anomaly. None work however they note that any mission to test the anomaly will also be a useful probe of the mass distribution in the belt.

McKernan et al. place limits on ionic column densities of Galactic halo hot gas using Chandra grating spectral observations of 15 type I AGN.

Tagliaferri et al. summarize the prompt X-ray emission lightcurve from Swift bursts.

Dupke & Bregman survey constraints on bulk motions in clusters based on ASCA spectra.

Read et al. describe progress towards the XMM slew-survey which will cover the sky at 2-10 keV ten times deeper than all other surveys in this energy range.

Vaughan & Uttley consider what is required to detect QPOs from AGN and conclude that the most efficient technique requires and all-sky version of the RXTE ASM.

Tuesday, June 14, 2005

wtmapfix in extractor

Lorella pointed out a problem with the Swift/XRT data in xselect. The WMAPs do not have -1 in pixels outside the selected region despite having wtmapfix set to yes. The problem arises because the XRT uses the same coordinate system for image and WMAP and extractor automatically resets wtmapfix to no in this case. I fixed this so that in this case the WMAP fix to convert the region from image to wmap coordinates is not done however pixels outside the region are still set to -1.

Keywords: heasoft, extractor, Swift

Monday, June 13, 2005

Speed-up of NEI APEC models

After I added the thermal and velocity-broadening the NEI APEC models slowed down even when there was no broadening in use. I fixed this to some extent by trapping lines that fall completely outside the response energy range at an earlier point in the code.

Keywords: heasoft, xspec


Perryman et al. review the prospects for detection of extrasolar planets.

Jane Turner et al. analyze XMM data of Mrk766 looking in the energy-time plane for evidence of orbital motion around the SMBH.

Thursday, June 09, 2005

gaussline function

Added a trap for zero width to the start of the gaussline function in xsgaul.f. This should be speed up the code and also fixes an occasional seg fault. Checked into the cvs depository for both v11 and v12 but not made public. I'm waiting for Frank Haberl to get back to me on a problem he has had with the gaussian model that I can't replicate locally.

Keywords: heasoft, xspec

NEI models

Terry Gaetz spotted that the NEI models don't respond to the abund command and always use Anders & Grevesse relative abundances. Fixed as 11.3.2h. Will also go out as a v12 patch.

Keywords: heasoft, xspec

nsa model

George Pavlov passed along some changes to the documentation for this nsa model. The references were only for non-magnetic models. Modified xspec.hlp but didn't put out as a patch.

Keywords: heasoft, xspec

Wednesday, June 08, 2005


Udalski et al. (the OGLE team) find a second case of a Jupiter mass planet using gravitational microlensing.

Thomas et al. consider the effects of GRBs on the Earth and in particular whether a nearby GRB could be an initiator of a mass extinction event.

Ensslin & Vogt develop an analytic model for magnetic turbulence in cool cores of clusters.

Brighenti & Matthews suggest that a fraction of the Fe from SNI in early-type galaxies could rapidly radiatively cool and hence not be measured using X-ray observations.

Glazebrook & Blake calculate the sensitivities of very large redshift surveys to measure the baryon oscillations and hence determine the evolution of dark energy.

Pilla et al. describe a score test for distinguishing a new source from a random fluctuation.

Young et al. analyze a 522 ksec Chandra HETG observation of MCG-6-30-15 and conclude that the spectrum is consistent with a broad relativistic line round a fast rotating SMBH.

Tuesday, June 07, 2005

tclout simpars seg fault

Piero Ranalli reported getting seg faults under Linux when running tclout simpars. Turned out to be an error assigning a string size. Fixed as 11.3.2g.

Keywords: heasoft, xspec

xselect HXD

According to Terada-san the HXD instrument name should be changed from HXD to HXD-WELL. Also the WMAP will be created as UNITID vs. PIN_ID. Check in appropriate changes to xselect.mdb.

Keywords: xselect, Astro-E2

Friday, June 03, 2005

xselect and Astro-E

When I checked in the change to xselect.mdb for TELESCOP=Astro-E2 I accidentally overrwrote the changes for the default WMAP. Corrected this so that fbin=hbin=1 and imagecoord=wmapcoord=SKY.

Keywords: xselect, Astro-E2

v11 projct model

Glenn Morris hit a seg fault when using projct with > 25 shells. This occurred in the set-up for a diagnostic message writing out the projection matrix. Just truncated this to only write 25 columns. v11.3.2f.

Keywords: heasoft. xspec

Wednesday, June 01, 2005


Mannheim reviews the underpinnings of standard gravity theory and considers what is required to explain dark matter and energy as errors in the current theory.

Jacobsen et al. review the prospects for detecting possible Lorentz violations predicted by quantum gravity theories.

Takizawa presents 3-D hydro simulations of a moving substructure in the ICM.

Clarkson & Maartens argue that if string theory is correct and the Universe is an embedded 3-brane then this will introduce oscillations in the GW signal from BHs.

Treister & Urry show that the optical/IR/X-ray content of deep surveys and the spectral shape of the XRB can be explained by a model with a constant ratio of obscured to unobscured AGN.

Kocsis et al. calculate LISA error ellipses for BH mergers and argue that if they are accompanied by Eddington-limit quasar activity they can be uniquely identified to z~1.

Buote et al. present Chandra observations of A644, a radio-quiet cool-core cluster. They find that the inward decline in temperature and entropy reverses inside the core. The peak is offset from the centroid with the cD midway between suggesting a merger.

Finoguenov et al. put together XMM samples of groups and galaxies to confirm an entropy ramp as the explanation for the scaling relations and find a mild evolution in entropy of clusters.

Tuesday, May 31, 2005


Williams et al. discuss Chandra and FUSE absorption lines towards Mkn421 and argue that they have detected the IGM at z~0.

Finoguenov et al analyze an XMM mosaic of A3266 and find an extended region of low entropy gas which they interpret as stripped from an infalling subcluster core.

Wolfe and Melia argue that continuous stochastic acceleration cannot explain the hard X-ray emission from Coma because the energy gained by the particles is redistributed over the whole plasma on a fast timescale.

Crawford et al. present optical and Chandra observations of the filament in A1795.

Willis et al. claim detections of polarization in GRB based on detailed modelling of Compton scattering of the prompt emission off the Earth's atmosphere.

Berger et al. present the results of optical, near-IR and radio follow-ups of Swift bursts. Up to a third of the bursts may be dark.

Subramanian et al. discuss turbulence and magnetic fields in the ICM.

Brogan et al. identify a HESS source with a source of non-thermal radio and X-ray emission due to a young shell-type SNR.

Monday, May 23, 2005

posm model

Chris Shrader provided an improved version of the posm model which performs a trapezoid integration over each energy bin. Available for v11 as bug fix 11.3.2e.

Keywords: heasoft, xspec


Terry Gaetz spotted a couple of errors in sizing of the param array in kbmodels.f. These generated compiler warnings but probably had no effect. Fixed them.

Keywords: heasoft

Saturday, May 21, 2005

GravStat 2005: Bose

Networks of broadband detectors.
A single broadband detector can be thought of as a network of narrow band detectors.
Mergers have 3 phases - s/n may be small in each phase but combined may exceed threshold. How can we be sure we are associating 3 phases correctly - consistency checks.
Networking broadband detectors -> sky positions, stochastic GW background. Computationally very intensive.
Detectors have hugely different sensitivities - network dimensionality reduced for weakest detectable sources (only most sensitive detectors are likely to see them).
Network of aligned detectors - same signal in all detectors (to within time delay), can trigger on one detector and search on others, improved background determination. But blind spots and cannot find polarization of transients.
Unaligned detectors - can unravel more parameters, signal coverage better.
With more detectors there are more ways of analyzing the data - how do we decide which are best ?
What happens if different detectors have different noise characteristics - gaussian vs non-gaussian ?
In a network of detectors do you set confidence intervals for each unique combination ?
With large numbers of detectors computational costs are high - tricks to control this mutilate the normality of the initial statistic pdf.
How stringent are requirements on calibration accuracies across the network ?
How and when sould we effect astrophysical figures-of-merit, vetoes ? eg suppose derived position is where network has low sensitivity ?

GravStat 2005: Prodi

Time-coincidence search using bar detectors (IGEC). Template search - matched filters optimized for short and rare transients.
Many trials at once (9 pairs + 7 triples + 2 4-folds). Many target thresholds. Directional/non-directional searches.
Control of false dismissal probability - balance between detection efficiency and background fluctuations.
Background noise estimation - 10^3 time lags for pairs, 10^4-10^5 time lags for triples. GOF tests with background model.
Blind analysis - tuning of procedures before looking at data (no playground).
IGEC-2 has agreed on blind data exchange (secret time lag).
Resample by shifting event time series to get statistics of accidental claims.
Realized that technique good for upper limits but optimized for discoveries - false possitives hide true discoveries. Need to decrease false alarm probability (type I error).
Want to build confidence belt based on false alarm probability for each value of unknown parameter. Use Benjamini & Hochberg FDR procedure.
Open questions:
Check fluctuation of random variable FDR with respect to mean
Are we required to report a rejection of the null hypothesis ? - this is claim for an excess correlation in the observations at the true time, not taking into account measured noise background at different time lags - it might not be GW.

Friday, May 20, 2005

GravStat 2005: Summerscales

Max. entropy deconvolution of detector response.
Then as a test for supernova detection cross-correlated with all waveforms in Ott et al. catalog. Showed able to recover physics.
Simultaneous analysis of L and H time series to give one deconvolved "input" waveform.

GravStat 2005: Shawhan

GW transients: upper limits and discoveries. Waveforms may be known or unknown. Known depends on one or more physical parameters. Physically identical signals may have different source origins. Given source classes can produce different signals.

Selection of event candidates
Identify regions of interest - filter to produce a trigger. Use a low threshold then apply additional tests - waveform consistency, noise stationarity, coincidence among detectors, cross-correlation of datastreams.

Summarize the outcome - define a statistic which has some power to distinguish S+B from B eg events with S/N > some threshold.

Cleanest evidence for discovery is a p-value < some threshold. A frequentist confidence interval is a set of models for which the observed outcome was "likely". Maximum S/N ratio test (Brady et al. CQG 21, S1775, 2004).

Do we really need to calculate a statistic - can we use all the information available.
Is there another way to talk about discovery other than the p-value.
What is appropriate background rate ?
Why do a F analysis, a B analysis,... ?

GravStat 2005: Loredo (again)

Spatial coincidence (with Wasserman). Consider 2 objects - frequentist nearest neighbour test p(Bayesian coincidence assessment. Compare models of no repetition and repetition. Odds favouring repetition = 4 pi Int dn L_1(n)L_2(n) ~ (2/sigma_12) exp(-theta_12^2/2sigma_12^2), sigma_12^2 = sigma_1^2+sigma_2^2. Generalizing to more events is tough - number of pairs to calculate goes as N^4.

Bayesian Adaptive Exploration (with Chernoff). Sequential analysis.
Observation -> Inference -> Design

Stopping problem: binomial (fixed # of obs) and negative binomial (fixed # of particular type of object) give different frequentist test results. A Bayesian comparison does not depend on the stopping condition.
Maximum entropy sampling: learn the most by observing where we know the least.

GravStat 2005: Rawlins

Frequentist interpretation. Feldman-Cousins unified scheme for confidence intervals. A 90% CL interval is guaranteed to include the true parameter value in 90% of hypothetical experiments (note F-C technique actually overcovers most of the time).
Intervals (each correct) will look different depending on background, ordering scheme, and probability distribution assumed - so need to fix these before the experiment.
But what happens if you come up with a new background component after performing the experiment ?
When a first GW is discovered it will be investigated in detail to check for alternative explanations. We can't routinely examine the background at this level so we will be potentially vetoing based on information not originally considered.

Knowing in advance the veto procedure before looking at the final events helps a lot. If changes after the fact are unavoidable then understanding the process as much as possible helps estimate the errors.

What should be done ?
1. Open box and take what's inside - statistically pure but risky
2. Stop worrying and do the best you can. Establish "fire drill" procedures
3. Conduct two separate searches : one for upper limits and one for discovery. For latter limit yourself to best behaved data and post hoc veto.

If we publish 90% confidence limits why aren't there more claimed detections ?

GravStat 2005: Woan

Search for quasi-sinusoidal signal from triaxial NS. Large number of parameters, sime of large dimension. However signal is believed to be coherent on long timescales and may be phase-locked to the radio pulse.

If searching for a radio pulsar only need narrow bandwidth so can be in a clear region of the frequency spectrum. If frequency is not known then problem is that instrument has many lines that can be picked up by matched filters. However instrumental lines will not exhibit correct doppler/antenna pattern modulations.

Time-domain searches targeted MCMC over narrow parameter space. Frequency domain searches for isolated lines. Incoherent searches - Hough transform, stack-slide, powerflux.
Incoherent techniques are worth doing because coherent searches are over such a large parameter space that a source must be strong to be statistically significant.

LISA confusion - Umstatter et al 2005 blind detection and parameter estimation of 100 unkown sinusoids in noise of unknown variance. Frequentist approaches are fast but clumsy when making a final statement on sensitivity - can we recast in B terms. Is it sensible to use worsre case scenarios for upper limits ?

Given a posterior how do we make a statement about whether a detection has been made ? What is the best credible interval to use ?

GravStat 2005: Romano

Search for stochastic GWs by cross-correlating 2 GW detectors
Y = Int df s_1(f) Q(f) s_2(f)
where Q(f) is the filter. Look for Omega ~ f^alpha. Q normalized to give = Omega_0.

Split data into short segments and calculate Y. Downsample 16384 -> 1024 Hz. High-pass filter and window to reduce leakage. Calibrate in f domain. Sliding PSD estimation to eliminate bias. Remove coherent lines (nx60Hz, nx16Hz). Optimal filter for different spectral indices. H1-H2 shows broadband coherence due to acoustic coupling. B analysis with prior 1/Omega_max where
Omega_max is from previous analysis.

Marginalise over theoretical variances - estimating for observed Y. S3 H1-L1 fits theoretical variance very well. Doing search in S4 for anisotropic stochastic GW - eg center of Galaxy, Virgo cluster.

Are there more general relationships for more detectors ?

GravStat 2005: Roundtable

Giovani Prodi introductory remarks

1. Blind vs. explanatory analysis - use of priors, exploit F & B methods.

2. Noise background estimation - confidence required ? statistical uncertainties on background ? discriminate correlated noise from target gw signals.

3. Can we rely on statistics alone for gw searches ? what is added value of a posteriori physical information ? role of systematic uncertainties ?

4. Multiple observations - comparison & synthesis of different observations, control False Discovery Rate in multiple trials.

5. Validation of results of a network or a detector - independent analysis procedures, injections of s/w signals.

Comments by Daisuke Tatsumi

On 1) blind analysis ideal for 1st detection. Need full detector noise simulation (including burst noise).

On 2) most important is systematics

On 5) joint search program looks good.

Questions from Peter Shawhan

How much should astrophysical assumptions feed into Bayesian analysis of data ?
How much should assumptions on rates influence design of analysis procedures ?

General discussion

Should posteriors from previous experiments be used as priors ? This is done for pulsars. For LIGO the sensitivities are improving so rapidly that posteriors for previous runs are effectively flat.

What cuts do you apply on background ? This might depend on how strong a source you were looking for.

Types of noise: white, harmonic, burst, auto-regressive (1/f). If all these matter then very tough statistical problem.

Can create models looking for ill-defined targets eg Larry Bretthorst's work on searching for radar profiles of planes for US Army - priors for known planes plus low prior for a new type of plane which is very poorly defined. Unknown type of plane will not be detected till it it closer but it can be detected.

There are techniques to build likelihood from multiple time series that have linear correlations.

Critical test is: does signal/noise ratio improve as sensitivity improves.

xselect case-insensitivity

Since the Astro-E2 folks insist on having TELESCOP='Astro-E2' not 'ASTRO-E2' modified xselect so that it is case-insensitive for mission, detector, etc. names. This shouldn't matter for any other missions. Also copied xselect.mdb entries for ASTRO-E to those for Astro-E2.

Keywords: heasoft, Astro-E2

GravStat 2005: Finn

Sam Finn's talk on statistical issues for GW.

Inference requires assumptions:
Examples : Bound the rate of coalescing compact binaries as a function of mass : what can we surmise about binary synthesis and evolution.
: Bound amplitude of gravitational waves from a pulsar: how can we choose among models for nuclear EOS.
: Detect burst associated with GRB : what can we say about the central engine.

Regimes of interest
Today : weak (low snr) & rare (serendipitous)
Tomorrow: ground-based : strong at moderate rate
space-based : strong and (over-)abundant - confusion

We observe signals not sources
Stochastic: continuous, possibly modulated
Periodic: known frequency, unknown frequency
Bursts: characterized by eg waveform, (time-)frequency spectrum, energy spectrum, amplitude, bandwidth, duration

Multi-layered data analysis:
Data conditioning: removing artifacts - regression, vetoes, whitening (flat-field),...
Signal ID and characterization: amplitudes, durations, spectra, locations, bandwidths, waveforms, rates. classification - signals of same tyoe
Interpretation of signals as sources: source eg mass, spin, differential rotation; process - hypernova or binary coalescence, neutrino opacity etc.; population - mass function, spatial distribution, luminosity function, evolution,...

Where are we now ?
Focussed on signal ID and characterization - haven't seriously tackled interpretation.
Statistical tools used for ID and characterization:
confidence interval construction on rates (bursts, stochastic)
extreme value statistics (inspiral)
Bayesian credible sets (periodic signals)

Open questions:
Do we/did we see strong evidence for gravitational waves. Quantify strong.
How do we incorporate prior knowledge or experience without closing our minds to discovery ?
When and how may we "re-analyze" data ? ie carry out an improved analysis, incorporate new info.
How do we go about classifying signals ?
How do we select among physical models for phenomena ?
How do we infer population properties for incomplete and biased samples ?
How do we compare and combine different experiments.

Thursday, May 19, 2005

GravStat 2005: Loredo

Tom Loredo's introductory talk on statistics.

Inference: deductive/inductive
Statistical inference: quantify inductive inference -> probability

Consider set of models M_i with parameters P_i.
Parameter estimation - given model i what can we say about P_i
Model uncertainty - which model is better ? Is M_0 adequate
Hybrid uncertainty - models share some common parameters: what can we say about them ?

Frequentist (F): devise procedure to choose among hypotheses H_i using D. Apply to D_obs. Report long-run performance.
Bayesian (B) : calculate probability of hypotheses given D_obs and modelling premises using rules of probability theory.

Frequency -> Probability - Bernoulli law of large numbers
Probability -> Frequency - Bayes' original paper

B vs F
B more general: can in principle contemplate probability of anything
B more narrow: data only appear through likelihood function
F can always base a procedure on a B calculation.

Decision theory: a rule a(D) that chooses a particular action when D is observed.
Risk : R(o) = Sum_D p(D|o) L(a(D),o)
where L is the loss function. Seek rules with small risks.

Inference: F calibration - the long-run average actual accuracy ~ long-run average reported accuracy. Decision theory is used to decide between calibrated rules.

B decision theory : average over outcomes.

Wald's Complete Class Theorem: Admissable F decision rules are B rules. Less useful than appears because sometimes inadmissable rules are better than admissable.

Model uncertainty: B method requires alternative model.

Comparison of B & F: B credible regions are usually close to F confidence regions but often better. Decision results are very different.

Counting experiment with background known - B approach (Helene 1983), F approach (Roe & Woodruffe 1999).

Nuisance parameters : profile likelihood - maximise over nuisance parameters
L_p(P) = max_Q L(P,Q)
can be biased and confidence intervals too small. Modern F approach is asymptotic adjustment
L_p(P) x |I_QQ(P)|^-1/2
where I_QQ is information matrix for Q. Alternatively evaluate F properties of B marginal solution.

Hypothesis testing :
Noone does Neymann-Pearson - you need to pick alpha ahead of time and only report this eg quote a 2 sigma detection even if actually 10 sigma.
Fisher proposed p-values to get round this. But depends on data and easily interpretable. p-values don't accurately measure how often the null will be wrongly rejected.
Recent work on conditional testing solves some of these problems. Comparison with B methods by Berger.

Multiple tests - False Discovery Rate. Active research topic.

Non-parametric situation between F and B is much more controversial and has not convered.

Keywords: statistics


For Astro-E2 XRS we want to be able to use genrsp to make the response. This requires adding the capability to specify and calculate escape peaks (assumed gaussian in shape). I've made the changes to support this except for the code in rdinpd which will actually get the main and escape peak information. This is waiting on the definition of the FITS file.

Keywords: heasoft, response

Monday, May 16, 2005

Mac freebies and wiki stuff

From Lifehacker :

Mac freebies : TextWrangler text editor, Quicksilver App launcher, GmailStatus notifier, iTerm terminal, VLC media player.

Wiki stuff : Instiki, GTD TiddlyWiki

Wednesday, May 11, 2005

v12 current issues

The following are larger outstanding issues I need to think about

1. xmmpsf model needs addition of ability to read and write FITS files with the fact array. Also need to work out why v11 and v12 results differ.

2. The /b syntax for background models is no longer available. Can we provide simple instructions or even a tool to convert v11 scripts.

3. Need to add the extend command. Is there a better way to deal with this than in v11 ?

Keywords: xspec

Attilla Kovacs: The Universe seen through the eyes of a SHARC

Attilla Kovacs from Caltech gave the EUD seminar on results using the SHARC II array. This 2-D bolometer array built by Harvey Moseley's group is on the Caltech Submillimeter Observatory on Mauna Kea. The sky is so bright and variable at 350 microns that it is equivalent to observing a 16th mag star in the daytime. They use an iterative process involving successive max likelihood solutions for each process creating signal or noise in the image. Looking at a wide variety of objects from solar system to distant radio galaxies.

Steinn Sigurdsson: Planets round WDs

UMCP colloquium by Steinn Sigurdsson on finding planets around WDs. The idea is to look at a system where the contrast between star and planet is less. DAX WDs are H WDs but with metal lines in their atmospheres. The lifetimes for such lines are short since they should settle. One theory is that the WDs are being bombarded by comets (note that Lee Mundy wondered about X-ray flares in this case). However comet rates are ~100 times too low. Steinn worked out that if there is a planetary system then comet rates could be increased as required. So searched 6 nearby DAZs with HST. Found a number of candidates none of which have been confirmed by proper motion tests. Impressive image taken with Gemini(N) AO system where they guided on the WD to get a 50 mas resolution.

Monday, May 09, 2005

gauss model in v11

John Houck and Mike Nowak spotted a potential problem with xsgaul.f when the gaussian line extends beyond the lowest energy channel. Fixed this as 11.3.2d.

I then noticed that a number of models are not in sync between v11 and v12. It looks like a number of minor bug fixes and enhancements made over the last couple of years didn't make it into the files in the XSFunctions directory. Files changed are compbb.f, cont.f, ionsneqs.f, ldaped.f, neispec.f, oneispec.f, pileup.f, reflct.f, smdem2.f, sumape.f, sumdem.f, xeq.f, xsdskb.f,
xseq.f, xsgaul.f, xsnteea.f, xsvape.f

Keywords: xspec

Friday, May 06, 2005


Ostriker et al. present a simple polytropic model for the ICM.

Nulsen et al. find a Mach 1.65 shock in the X-ray image of the cluster around Her A.

Nevaleinen et al. describe XMM EPIC background modelling.

Page et al. suggest that it may be possible to use observations of minor planets in the outer Solar System to test the Pioneer Effect.

Matheson and Safi-Harb put together all the Chandra data on G21.5-0.9.

Begelmann & Nath invoke a feedback model to explain the MBH-bulge sigma relation.

Angulo et al. argue that a survey of clusters at z~1 looking for baryon fluctuations can determine dark energy w to better than 10% without requiring knowledge of the cluster mass.

Jenet et al. show that radio observations of 40 pulsars with a timing accuracy of 100 nano-seconds could detect the effects of the stochastic gravitational wave background from merging BHs. This would take 5-20 years of observations depending on the actual background.

Fabian et al. analyze six XMM observations of 1H0419-577 and argue that the lowest flux state is dominated by emission from within a few gravitational radii of the BH, which must be in an extreme Kerr state.

Keywords: ICM, XMM, Gravity, BH, SNR

Monday, April 25, 2005

xspec 12 diagnostics for reading files

v12 doesn't write out much helpful information when a file is rejected for some reason. Made a start at fixing this by adding diagnostic message output at chatter level 25 to OGIP_92aIO::fileFormat in DataFactory/OGIP-92aIO.cxx and DataUtility:readArrays in Data/DataUtility.cxx.

UPDATE: A better solution is to add a call to FITS::setVerboseMode in the chatter command code so that CCfits verbosity is turned on if chatter >= 25. This is now implemented in 12.2.0x.

Keywords: heasoft, xspec

Friday, April 22, 2005

xspec 11.3.2 patches

Added 3 patches for 11.3.2.

11.3.2a The new cfitsio seg faults on a call to ftgcvs if the column number is zero even if the input status is non-zero (and hence should just fall through). This broke reading type II pha files. I worked around the problem by modifying rdsfg2.f so it doesn't call ftgcvs with zero column number.

11.3.2b Roderick pointed out that under v12 model functions look for data in fgmodf but in v11 they use fgdatd. This makes it annoying for anyone trying to supply a local model for both versions. I fixed this by adding a fgmodf entry for v11 which returns the same directory as fgdatd.

11.3.2c The compps model seg faulted under Linux due to variables not being saved. I thought I'd caught all these but perhaps Juri added these after my last round of changes.

Keywords: xspec, heasoft

Wednesday, April 13, 2005


Nicastro et al. detect OVII and NVII lines from the WHIM on the line-of-sight to Mkn 421 using Chandra TOO observations when the source was in outburst. The measured baryon density is consistent with model predictions.

Berti et al. study what LISA will be able to determine from MBH inspirals.

Melbourne et al. present first results using laser guide star adaptive optics on Keck to do NIR imaging of GOODS sources. They have a NIR FWHM of ~0.1".

Kotov & Vikhlinin present XMM spatially-resolved temperature and density profiles of clusters in the range z=0.4-0.7.

Keywords: WHIM, GW, AGN, clusters

Thursday, April 07, 2005


Benacquista and Holley-Bockelmann look at LISA confusion noise from compact WD binaries.

Fusco-Femiano et al. analyze two BeppoSAX PDS observations of A2256 and find a hard X-ray signal consistent with that seen using RXTE.

Tod Strohmayer shows that the putative compact X-ray binary RX J0806.3+1527 has a spin-down rate of 3.77+/-0.8 x10^-16 Hz/s consistent with gravitational radiation losses.

Keywords: GW, clusters

Wednesday, April 06, 2005


Reed et al. include gas cooling in high res N-body simulations and find small groups of galaxies can form by z~30 unless prevented by feedback processes.

Murray et al. present the results of their 5ksec deep Chandra survey of the 9.3 sq deg Bootes field.

Vikhlinin provides an algorithm to predict measured temperatures when actually observing a multi-component thermal plasma.

Keywords: clusters, AGN, star formation

Monday, April 04, 2005


Wilson et al. find clusters in 0.09 < z < 1.6 using a R-[3.6] colour from Spitzer.

Colafrancesco calculates the SZ effect from ICM cavities.

Brueggen et al. calculate ICM bulk motion Doppler shifts and find that the kinetic luminosity of an AGN in the center of the cluster can be estimated with 10 eV spectral resolution instruments.

Miller et al. present the C4 catalog of 748 clusters of galaxies found in the SDSS Second Data Release which covers approximately 2600 square degrees.

Humphrey & Buote study the X-ray properties of a sample of 28 early-type galaxies. They find no evidence that the ISM is more metal-poor than the stars. They do find the low O to Mg abundance ratios seen in centers of groups and clusters and such they are due to an additional source of alpha-element enrichment, perhaps pop III.


Wyithe extends the log-linear relationship between SMBH mass and spheroid velocity dispersion to a log-quadratic relationship predicting much higher densities of very massive (>1e10) BHs.

Charbonneau et al. detect IR emission from the eclipsing planet TrES-1.

Deming et al. detect IR emission from eclipsing planet HD209458b. The find that high orbital eccentricity is unlikely ruling out the possibility of tidal heating causing the planet's anomalously large radius.

Ledlow, Owen & Miller have spectroscopically identified 77 new members of the Cygnus-A cluster bringing the total to 118. They suggest the system is a merger between two Abell richness class I clusters viewed at a projection angle of 30-45 degrees, 0.2-0.6 Gyrs before core passage.

Hamilton presents lectures on cosmological power spectrum estimation. The first covers basics and the second linear max. likelihood.

Melott et al. suggest that the late Ordovician mass extinction event may have been due to a Galactic GRB.

Keywords: SMBH, extrasolar planets

Wednesday, March 30, 2005

xmmpsf model

I suspect that the xmmpsf model in v12 could be speeded up. The xmmFact method copies the PSF array inside the target region loop which cannot be the most efficient approach.

Keywords: xspec, heasoft

CCFits fitsPointer() method

This method appears to return the fitsfile* for the last HDU in the file regardless of the current HDU. To correct this set the HDUposition element of the fitsfile struct. This should be fixed in CCfits at some point.

Keywords: heasoft, CCfits

Saturday, March 26, 2005

Extra models

Added the URL for the extra models page to the end of the list of available models in xspec (both v11 and v12). If we move to a browser help in v12 may be able to automatically add these extra models to the on-line help.

Keywords: xspec, heasoft

Opt/UV extinction model

Martin Still extended the Cardelli et al. extinction routine down to 909 Angstroms . Added a redshifted version - required for Swift UVOT data.

Added the model to both v11 and v12 although still need to modify documentation for v12.

Keywords: xspec, heasoft

Wednesday, March 23, 2005

xspec v12 local model issues

Tried out building v12 local models. Firstly, note that initpackage didn't run standalone because it looks for environment variable XSPECROOT which is set when xspec starts up. Fixed this by looking instead for HEADAS. Also, trapped case of HEADAS not being set (which means getenv returns a null pointer). Note that when running standalone the user has to follow initpackage with an hmake in the directory with the local model code. When using the initpackage command from within xspec this happens automatically.

Old v11 models that include don't work at the moment. initpackage needs to copy the
include/xspec.h file into an file in the directory with the local model code.

The v12 local model paradigm doesn't work under OS X for fortran routines including common blocks because these cannot be placed in a dynamic library. Note that any fortran routine which includes falls in this category. We will have to either require no fortran common blocks in local models under OS X or provide an alternative mechanism to build static libraries which would be linked into the xspec executable when it is built.

Keywords: xspec, heasoft

Tuesday, March 22, 2005

xspec 11.3.2

Updated the version number for xspec 11 to 11.3.2 for the new release. This is essentially just a bug fix release with a couple of the extra models now included automatically.

Keywords: xspec, heasoft

Friday, March 18, 2005


Pawl et al. create mock Astro-E2 observations from their simulated clusters.

Seager et al. consider the spectroscopic biosignature of extrasolar planets.

Gies & Hesel claim that ice ages correspond to the Sun traversing spiral arms.

Sanders et al. present deep Chandra imaging of the Perseus cluster. They find a high-abundance shell which they suggest is the edge of a fossil bubble. They also detect non-thermal emission with a total luminosity of 4.8x10^43 erg/s and use this to map the magnetic field in the core of the cluster.

Weisskopf et al. provide a detailed description of the Chandra hardware and in-orbit performance.

de Diego et al. argue that the Pioneer anomalous acceleration is due to the Kuiper belt.

Keywords: clusters, extrasolar planets, Chandra, Pioneer

Katherine Blundell: SS433

Seminar by Katherine Blundell of Oxford on optical and radio observations of microquasars and in particular SS433. Neatest result was analysis of new VLA image. She showed that assuming SS433 shoots ballistic plasma blobs out completely symmetrically then the differences in observed shape from the two corkscrewing jets are due to relativistic aberration. This enables the jet speed to be determined accurately to 0.26c and hence the distance to 5.5 kpc. She also noted that the model is not a perfect fit and can be improved by allowing the speed to vary between 0.24 and 0.28c. Further she showed that by combining the redshifts of symmetric blobs one can determine independently the velocity and the cone opening angle. A PSD of the velocity shows a signal at the binary frequency. This may be due to eccentricity in the orbit.

Keywords: microquasars, SS433

xspec 11 seg fault in fakeit

Bryan pointed out a seg fault under OSF in xspec v11 when running a fakeit. Turned out to be an attempt to strcpy a null string. Strange that it hadn't turned up before. Will be fixed in the forthcoming heasoft release.

Keywords: xspec, heasoft

Monday, March 14, 2005


Fabian et al. present initial results from a 200 ksec Chandra observation of the Centaurus cluster. They see bubbles, semi-circular edges and filaments. Some edges have sharp temperature increases and abundance drops.

Barcons et al. find a single absorption line in a 93 ksec XMM-Newton RGS spectrum of the Bl Lac PKS 0548-322. If this line is OVI then the absorber is at z=0.058. The column is however much larger than expected.

Rhook & Wyithe calculate LISA detection rates for SMBH mergers and predict ~15/year with S/N > 5.

Bauer et al. use Chandra to study 38 X-ray luminous clusters in z ~0.15-0.4 and find 55% have cool cores and 34% have t_cool less than 2 Gyr.

Zane et al. find a possible absorption feature in the XMM PN&MOS spectra of the isolated NS RBS 1774.

Keywords: clusters, IGM, SMBH, GW, NS

Downsampling in HHT

I don't see how this can work in the way suggested. In any IMF Omega varies smoothly on timescales longer than the averaging time (as it must because faster variation has been removed in earlier IMFs). We do not gain a sqrt(N) advantage which would require Omega to vary randomly over an averaging time.

Keywords: HHT, GW

Hilbert transform in HHT code

Examining Omega vs Time in individual IMFs showed a high frequency oscillation - there is a clear trend with successive bins above and below the trend. This oscillation does not show up in Delta but does in Kappa (the Hilbert transform). This led me to examine the Hilbert transform code. The Hilbert transform algorithm is to forward FT the time series, modify the result, then inverse FT. The imaginary part of the result is the Hilbert transform while the real part should be the input time series. Comparing the input time series with the real part of the result showed a difference at the ~1% level. This is much more than the numerical accuracy of the code.

Googling to find other descriptions of the algorithm I found a minor error in the code. The first and Npoints/2 + 1 points in the FFT should be left unchanged - not multiplied by 2
(like the 2 - Npoints/2 points). Fixing this removed the difference between the input and output time series. Unfortunately, it still left the oscillation in the transform.

I don't understand the origin of this oscillation at present but I was able to remove it by running a three-point triangular filter over the transform array. This in turn removed the high-frequency oscillation in the Omega vs Time plot.

Keywords: HHT, gravitational waves

Saturday, March 05, 2005

error in Huang et al. 1998

Equations 6.3 and 6.4 in Huang et al. Proc.R.Soc.Lond. A, 454, 903 are in error. In the double summation j should run from k+1 to n+1. I suspect there should also be a 2 in front of the summation. Note of course that X^2(t) should be outside the parentheses.

Keywords: HHT, GW


Added Juri Poutanen's compps model (version 5/12/04) to xspec. Modified the comprefl.f and xscompps.f to call greencj from the pexriv model instead of greeion included in comprefl. This fixes a bug under Linux and removes replicated source code. This could lead to problems if pexriv and compps are run simultaneously although there is little physical justification for that.
Need a couple of paragraphs from Juri for the help.

Keywords: xspec, heasoft, comptonization

Thursday, March 03, 2005


Mullis et al. have serendipitously discovered an X-ray luminous cluster at z=1.4. The velocity dispersion is 760+/-260 and there are a large number of red galaxies.

Keywords: clusters

Michael Mumma: Methane on Mars

Mike Mumma gave the Goddard Science Colloquium last Friday and described recent work detecting methane on Mars. This has a rocky history as there have been several claims over the last 20-30 years which have not been confirmed. The significance of a detection is that most methane on Earth is biotic. Methane on Mars could be abiotic but that would imply that the planet is geologically active which is not thought true at the moment. Mumma emphasized the importance of simultaneous imaging because ice clouds in the Martian atmosphere will reduce the column observed hence change the calculated abundance. His team have been performing long-slit near-IR spectroscopy using IRTF and Gemini South and they have clear detections of methane which is spatially variable. They are now looking for correlations with ground features, temperature etc. Once the geographic sources of methane have been identified then other tests can be performed, ideally involving in situ measurements of 12C/13C ratios which are diagnostics of biotic origins.

Keywords: astrobiology, Mars

Wednesday, March 02, 2005

Biman Nath: Entropy in the ICM and AGN

Biman Nath gave the UMCP Astronomy Colloquium. He reviewed the entropy of the ICM and in particular that in groups. S = T/n^2/3. If clusters are created at the same time we expect S to go as T but it goes as T^0.65. Further we expect L to go as T^2 however it goes as almost T^3. These imply something other than gravity determines the structure of the ICM. The effect is particularly marked in groups. One possibility is that galaxies form more efficiently in groups leading to the low S gas to cool out and be replaced by high S gas falling into the center. This may have some effect but cannot explain the observations on its own. The alternative is heating either by AGN or cosmic rays. There is good evidence now for AGN energy input into the ICM. The unknown is whether this can happen at higher redshifts and to the extent required. A fascinating new result (Croston et al 2005) seems to show that those groups containing radio-loud AGN have higher entropy than those having radio-quiet AGN. I pointed out in a question that since entropy is a time integral over the lifetime of the cluster this would imply that AGN which are radio-loud now were radio-loud in the past (and similarly for radio-quiet). Nath wondered whether the observed entropy would change while a radio-loud AGN was active.

Keywords: clusters, AGN, entropy

Tuesday, March 01, 2005


Cooray & Seto argue that LISA will be able to determine the distance to the LMC using observations of close WD binaries. Their estimated uncertainty is competitive to that from SIM or GAIA.

Merritt et al. argue that luminosity distributions of early-type galaxies and mass profiles of LCDM halos can be described by a Sersic law (log slope of projected density is a power-law of radius). This works better than NFW for LCDM halos.

Enoki et al. calculate gravitation radiation from merging SMBHs using a semi-analytic model of galaxy and quasar formation.

Mainieri et al. look at optically faint X-ray sources in the CDFS and use photometric redshifts to examine the distribution of sources too faint for spectroscopy. They still find an overdensity of z<1 sources wrt background synthesis models. 25% of the sources are absorbed QSOs.

Anania & Makoid argue that the Pioneer 10 anomalous acceleration can be explained by bending of background gravity behind the Sun (analogous to light bending).

Keywords: Gravitational waves, dark matter halos, AGN

error command in v12

I went through the XSfit/Fit/FitErrorCalc.cxx code and made changes to match those in the v11 error command added over the last year. The changes included the recent fix for when the soft and hard limits differ (clcunc.f 1.27), the fix for numerical accuracy problems near the hard limits (clcunc.f 1.26), setting the initial trial to a maximum of half the hard limit if the default method gives a value outside the hard limit (clcunc.f 1.23), and the randomized choice of a value between xmin and xmax instead of always picking (xmin+xmax)/2 (clcunc.f 1.21).

Questions still to consider: does v12 handle eigenvalue data correctly (clcunc.f 1.24) ? Are new parameters saved correctly if a new minimum is found (clcunc.f 1.25) ? Should the random number generator be initialized (clcunc.f 1.22) ? What happens if curdel is < ylimit(1) (clcunc.f 1.22) ?

UPDATE: Included the clcunc.f 1.22 changes. The others require discussion with Craig.

Keywords: heasoft, xspec

Monday, February 28, 2005

error in lstat fitting

Fixed error in lstat fitting spotted by Craig - dtconv was used in ab_lstat before being defined. Probably a mistake introduced when changing areascal and backscal to vectors.

Keywords: heasoft, xspec

Saturday, February 26, 2005

extractor and NULLs

Fixed extractor so that it rejects events whose TIME column contains a NULL. Note that only the TIME column is tested for NULLs.

Keywords: heasoft, extractor

Wednesday, February 23, 2005


Bryan & Voit use numerical simulations of cluster formation to argue that much of the ICM cools at high redshifts hence any heating mechanism to provide the extra entropy must operate at high redshifts as well.

Ballantyne & Fabian analyze XMM-Newton observations of the BLRG 4C+74.26 and find evidence for a relativistic Fe line extending into the ISCO for a maximally rotating BH.

Sesana et al. compute the expected GW signal from coalescing MBHs and predict ~90 events above S/N=5 in a three-year LISA mission.

Keywords: Clusters, AGN, Gravitational Waves

Tuesday, February 22, 2005

xselect Chandra response generation

CIAO 3.2 introduces a new tool, mkacisrmf, for building ACIS RMFs. I modified the xselect Chandra response generation script (xsl_chandra_acis_makeresp) to look for mkacisrmf and use that in preference to mkrmf.

Note that this script doesn't test whether the input file used the appropriate gain file for mkacisrmf.

Keywords: heasoft, xselect

Monday, February 21, 2005

Lightcurve output from extractor/xselect

Martin Still requested a new option for xselect/extractor. Currently the lightcurve output writes times relative to the start bin (ie starting at zero) with the offset from spacecraft time given by the keyword TIMEZERO. Martin wanted the option to have TIMEZERO set to zero so that it is easier to combine lightcurves from different observations. This is now implemented using the extractor boolean parameter lctzero - set this to no for TIMEZERO=0. Within xselect give the argument offset=no to the extract lightcurve command.

Keywords: heasoft, xselect, extractor

Thursday, February 17, 2005


Realized that dummyrsp with channel offset and size specified requires that the number of energy bins equal the number of channels. If this is not the case then a seg fault will occur. So, improved the help to make this clear and modified dmyrsp.f to force this condition if the user tries to violate it.

Keywords: heasoft, xspec

Wednesday, February 16, 2005


Motl et al. calculate the integrated SZE effect for a sample of theoretical clusters with different assumed baryonic physics. They show that the integrated SZE provides a very accurate estimate of the mass.

Yao and Wang detect NeIX, OVII, and OVIII absorption lines in Chandra spectra of XRBs and use these to study the large-scale hot interstellar medium of the Galaxy.

Quirrenbach summarizes current technological progress on space-based coronographic imaging to find planets.

Keywords: clusters, ISM, planets

Wednesday, February 09, 2005


Phil Uttley and colleagues show that the rms-flux relation in AGN and XRB implies a non-linear, exponential form for their light curves. The variability process must be multiplicative (not shot-noise).

Higdon et al. use Spitzer observations of a field surveyed by the VLA and Chandra and conclude that optically-invisible radio or X-ray sources are not generally detected at 24 microns implying that they are unobscured AGN.

Jones and DeYoung perform MHD modelling of relic radio bubbles in the ICM and confirm that magnetic fields can stabilise the bubbles giving them lifetimes of 10^8 years.

Tuesday, February 08, 2005

Contour plots and xhistory

A couple of small xspec bug fixes.
11.3.1u The label with minimum and contour levels was being overwritten in plot contour.
11.3.1v The xhistory fit package was not being written out. I think I commented this out of lvmrun.f when we were moving code to v12. Only the JPL folks use this at the moment.
Updated this on Feb 9 by moving wfthis call from lvmrun to lvmfit so it occurs after the fit parameter object is set.

Keywords: xspec

Thursday, February 03, 2005

Seminar: John Baker on MBH mergers

John gave a lunchtime PSU simulation and sources talk remotely from Goddard. He summarized the interest in observing massive black hole mergers using LISA. Vecchio has recently argued that at least six months of observations are required to constrain important binary MBH parameters. This constraint requires that planned LISA sensitivity be improved at the low frequency (<>1e6 Msun) black holes at high (z>5) redshifts. If we can also get physical constraints from the merger/ringdown then this requirement is eased.

John also summarized recent numerical GR work. The Lazarus collaboration is working on fourth-order differencing - an approach that should provide much improved accuracy for a given amount of computation. Initial work is promising. The Goddard group is working on adaptive mesh methods to calculate the GW signal in the far-field. The most recent calculation is of a head-on BH-BH collision where the outer boundary of the calculation is at 256 M with steps in the resolution at 8, 16, ... M.

Keywords: Black holes, GR, LISA


Pizzolato and Soker consider the analogies between cavities in PNe and in X-ray images of clusters and suggest that it may be possible to find binary black holes based on the symmetry of the cavities created.

Duane Liedahl looks at the effects of resonant Auger destruction on Fe K lines from compact sources.

Sturrock et al. give statistics based on combining two or more power spectra.

Keywords: Black holes, X-ray spectroscopy, statistics

Constellation-X matrices

I created the latest iteration of the Constellation-X response matrices. All effective area numbers were supplied by Paul Reid (CfA) in Excel files (ipg_020105.xls and opg_020105.xls). He included all detector filter and QE efficiencies. There are two basic options. The In-Plane Grating (IPG) is the old baseline while the Off-Plane Grating (OPG) is the new proposed, higher-resolution option. The two options cover different regions of the mirror so the calorimeter effective areas also differ.

The calorimeter (XMS) response matrices assume a 2 eV FWHM resolution which is independent of energy. Effective areas were supplied from 0.25 - 10 keV and the responses were created with 0.0003 keV energy bins.

The IPG RGS matrices are for three orders with resolutions (FWHM) of 0.087, 0.0435, and 0.029 Angstroms, respectively. All three matrices cover 5 to 50 Angstroms with energy binning of 0.01, 0.005, and 0.003 Angstrom, respectively.

The OPG RGS matrices are also for three orders with wavelength-dependent resolutions supplied by Flanagan and Rasmussen (in files FR_OPG_res_m#.dat). The first order matrix covers 5 - 50 Angstroms with binning 0.003, the second order 5 - 38 with 0.0015 binning, and the third order 5 - 25.5 with binning 0.001.

All matrices have COMMENT keywords in the primary header which describe the input (and were lifted from Paul Reid's Excel files).

Keywords: Constellation-X

Wednesday, February 02, 2005


Fixed a bug in genrsp for dispersive instruments whose resolution varies with wavelength and is entered via a file. As far as I know this option has never been used before.

Keywords: heasoft