Mark Krumholz: Turbulence, Feedback, and Slow Star Formation

UMCP astronomy colloquium by Mark Krumholz, a postdoc at Princeton after doing his PhD at Berkeley. The major mystery of star formation is why it is so slow - the SFR is 100 times smaller than predicted based on free fall times. Krumholz & McKee have developed a theory where turbulence holds up star formation and the turbulence itself is produced by star formation. He showed that a fairly simple physical theory reproduces the observation results. The remaining problems are taking into account magnetic fields and explaining the 100 km/s turbulence seen in starbursts.

Keywords : star formation

xronos window output from extractor

Fixed a bug that caused incorrect time ranges in the xronos window output (created for instance by extr curve in xselect). This was reported by Gulab Dewangan at CMU. There is still an unresolved issue if the selected region overlaps multiple chips with separate GTIs. The xronos output file contains the GTI for the final chip (in numerical order). This fix is extractor v4.63.

Keywords: xselect, extractor, HEAsoft

Don Lamb: Short GRBs

EUD seminar by Don Lamb. He summarized the story from last year on short GRBs then talked extensively about a HETE burst that appears short but has a photometric redshift of 1.5 (if heavily reddened) or 4.6. He suggested that there are problems with a classification scheme based on spectral hardness since results appear not to be consistent between different missions. The T90 classification also has issues because it is measured in the observed frame. If long GRBs are cosmological then the rest frame durations are much shorter (by 1+z) so the distinction between short and long is eroded. Finally he noted that the presence of a spectral lag is a good classifier of a long GRB but there are some short bursts with negligible lag but large error bars implying they are not highly structured (so lag cannot be well-measured) so these might actually be similar to long bursts.

Keywords: GRB

Preprints

Hudson et al. analyze Chandra observations of the double jet radio source 3C 75 at the core of Abell 400 and conclude that the two AGN are a bound system from a previous merger.

Rigby et al. consider why half of X-ray selected AGN are optically dull and conclude that extranuclear dust in the host galaxy plays an important role.

Stewart describes a procedure for matched filter detection of point sources in XMM images.

Ettori & Fabian argue that He sedimentation timescales in clusters were lower in the past leading to supersolar He abundances in the cores. This has the effect of reducing the measured metal abundances in these regions.

Wilson et al. use Chandra observations to investigate the bright limbs of the cavities in Cygnus A finding a weak shock and suggesting that the jet power is going into heating the ICM.

Barkhouse et al. present a survey for X-ray detected clusters in 130 archival Chandra pointings that are part of CHAMP.

Sandage et al. summarize their 15 year program to calibrate the SN Ia Hubble diagram using HST observations of Cepheids in nearby galaxies. They derive H0 = 62.3 +/- 1.5 (stat) +/- 5.0 (syst).

Kaaret et al find a 62 +/- 2.5 day period in the X-rays from the ULX source in M82.

Egami et al. describe Spitzer observations of BCGs and note an overall trend that clusters with shorter cooling times harbor more IR luminous BCGs.

Preprints

Kravtsov et al. use mock Chandra images of cluster simulations to compare X-ray estimators for the total mass and show that the new estimator Yx is remarkably good.

Werner et al. look at very hot AGB stars which are thought to have consumed their H shells exposing nucleosynthesis products.

Ascasibar & Markevitch use simulations of cluster mergers to show that cold fronts are caused by the sloshing of the cool gas in the central gravitational potential well.

warning messages from znibin and inibin

Both inibin and znibin (in the NEI code cont.f) generate a warning if the response energies extend beyond the available model data. Ensured that these warning messages are written out once not every iteration. This will be in next v11 and v12 releases.

Keywords: xspec, heasoft

Preprints

Kunz et al. introduce Bayesian complexity to assess how many effective parameters a data set can support.

Rasia et al. use five simulated galaxy clusters to investigate systematics in the determination of the total mass using X-ray observations.

Martini et al. survey 8 low-z clusters of galaxies for X-ray AGN and conclude that cluster galaxies host an AGN with a much higher frequency than supposed from optical observations.

Davis & Hubeny describe their relativistic, non-LTE atmosphere models for accretion disks in BH binaries.

Bregman & Lloyd-Davies conclude that the soft-excesses seen in clusters using XMM are not associated with the clusters but with Galactic features.

Allen et al. demonstrate a correlation between the Bondi accretion rate and the AGN jet power using Chandra data on 9 nearby ellipticals.

Preprints

Baker et al. present the gravitational waveforms from the final inspiral and merger of two BHs.

Simpson & Bridle consider the redshift sensitivity of various dark energy surveys.

Davis et al. fit disk-dominated black hole binary X-ray spectra with a number of different models and conclude that BHSPEC works best.

Holder demonstrates that nearly exact likelihood functions can be written down for galaxy cluster surveys.
Bregman et al. present FUSE OVI observations of three cooling flow clusters and find evidence for modest cooling flows down to temperatures of 10^5.5 K.

Begelman et al. describe a mechanism for generating massive black holes directly in the nuclei of protogalaxies without the requirement for a seed stellar mass BH.

Voigt & Fabian use Chandra observations of 12 clusters to determine the core mass profile and in 4 cases find flatter profiles than predicted by CDM. They interpret this as an underestimation of the mass in the center and suggest reasons for this to happen.

Piffaretti & Kaastra apply the effervescent heating model to XMM observations of 16 nearby clusters and find that it works in half the cases.

xspec 11 poisson data warning

The warning message written by stat cstat if the data are non-Poisson can be generated even with Poisson data if there are large numbers of counts/bin. This has been fixed by being more careful about numerical accuracy. Bug 11.3.2t.

Keywords: xspec, heasoft

Preprints

Williams et al. accumulate all the XMM calibration observations of Mkn 421 but fail to detect the absorption features seen using the Chandra LETG. However, their limits are consistent - the RGS being less sensitive due to the large number of bad detector columns, lower resolution, and fixed-pattern noise.

Linde et al. review eternal inflation and the multiverse.

Rines & Diaferio match X-ray cluster catalogs and the SDSS to examine infall patterns around 72 clusters. They demonstrate the reliability of the caustic technique for halo mass profiles.

Sereno et al. compare X-ray and SZ data for 25 clusters and estimate oblateness or prolateness. They find an excess of clusters aligned with the line of sight.

Tozzi introduces methods for determining cosmological parameters from X-ray observations of clusters.

Skinner considers the reasons for and against the use of Fresnel lens for focusing gamma- and high energy x-rays.

Nandra considers the emission sites of the narrow Fe K line cores and concludes that they are likely a mix of the inner edge of the torus and broadened emission from the accretion disk.

Garcia derives a simple approximation to the Voigt profile for use in studies of H absorption lines.

Tozzi et al. perform an X-ray spectral analysis of 321 sources in the CDFS.

Finn et al. describe the Testbed for LISA Analysis (TLA) project.

Best et al. look at radio-loud AGN heating as a regulator controlling the rate of growth of galaxies.

chkrmf

chkrmf was only checking for a MATRIX extension, not the also allowed SPECRESP MATRIX. Fixed this. Also, it was checking for required keywords in every extension - limited this to only the EBOUNDS and (SPECRESP) MATRIX extensions.

Keywords: chkrmf, heasoft

xinfix

Trapped a possible write past end of string in xinfix which occurs if the new text input by the user is longer than the input string for the routine. I think this is what caused the xspec v11 crash under Scientific Linux 4.2 reported by Glenn Morris.

Notice that there is a more general problem here with v11 in that the string containing the command input by the user which is passed down to the xspec subroutines appears to have the
length of the command string. So, any replacement prompted from the user for part of this string has to be shorter than the original or problems will occur.

Note also that I need to remember that xspec gets the xparse routines from libxantcl not libxanlib - I wasted several hours trying to work out why changes placed in libxanlib weren't showing up when running xspec.

Keywords: xspec, heasoft

xspwab

The model function routine xspwab.f used a real as a loop variable which produces an error using gfortran/g95 compilers since it is not part of the standard. Fixed this in both the v11 and v12 trees.

Keywords: xspec, heasoft

xspec 11 floating overflow in ratio plots

Ryan Porter ran into a problem when doing "data ratio" plots which turned out to be a lack of protection against floating overflows when evaluating the ratio. This is fixed in 11.3.2s.

Keywords : xspec, heasoft

Preprints

Humphrey et al. present Chandra results on 7 elliptical galaxies and find the data well fit by a model consisting of an NFW dark matter profile and a baryonic component following the optical light.

Ebeling et al. describe the ASMOOTH algorithm for adaptive smoothing to a constant S/N ratio.

Tozzi et al. summarize recent results from spectral analysis of sources in the CDFS.

Suyu et al. use Bayesian analysis to determine the optimal regularisation for source inversion in gravitational lensing.

Middleton et al. attempt to determine the spin of the BH in micro-quasar GRS1915+105 and conclude that jet production is likely powered by gravity not spin.

Brighenti & Mathews describe 2D gasdynamical models of jets in clusters and show that they can suppress the cooling and produce cluster temperature profiles similar to those observed.

Scarpa et al. look at the outskirts of globular clusters to see whether velocity dispersion falls off in Keplerian fashion. They find a flattening consistent with MOND or requiring DM which has not been suspected in these systems.

plot mkf fix

The plot mkf command in xselect fails under Linux due to a string overwrite in xsel_ftools.f. The problem was a buffer array with fixed size in a subroutine. The size of the buffer has been increased and a warning added if the new size is too small.

Keywords: xselect, heasoft

filter time file in xselect

The filter time file command assumes that the extension with the START and STOP times is the first extension in the file. Now generalized this so that it looks for the GTI extension.

UPDATE: Should have also looked for an STDGTI extension since this is written by maketime. Now fixed.

Keywords: xselect, heasoft

extractor fix for Swift UVOT lightcurves

Lightcurves from Swift UVOT event files could have TSTART=0 after time filtering. This is fixed in v4.62.

Keywords: HEAsoft, xselect, extractor

Preprints

Dupke & Bregman confirm their ASCA SIS Centaurus cluster velocity measurements using Chandra ACIS. They measure a velocity difference of 2.4 +/- 1 x 1e3 km/s.

Diehl & Statler present a technique for binning sparse X-ray imaging data based on weighted Voronoi tesselation which does not introduce the artefacts seen using csmooth. Open source code is available.

Bellazini et al. describe their integrated Gas Pixel Detector for X-ray polarimetry.

Rozanska et al. present warm absorber models for AGN from clouds under constant total (gas + radiation) pressure.

Brand et al. present results from the XBootes Chandra 9.3 sq deg shallow survey with deep optical follow-up. They find 47 sources that are blank-field down to R~25.5.

Bonamente et al. combine Chandra and OVRO data on 39 clusters to determine their distances using the SZ effect. They find H_0 = 77 with statistical errors of ~5 and systematic errors of ~10.

Hickox & Markevitch analyze the diffuse emission in the CDFN and CDFS and find that 79+/-8% of the 2-8 keV background has been resolved.

Peterson & Fabian review the X-ray spectroscopy of clusters of galaxies.

Daly & Djorgovski extend their model-independent approach to investigating dark energy.

Savage & Oliver present Bayesian source extraction methods.

Ford discusses efficient MCMC methods for analyzing the orbits of extrasolar planets including choice of the candidate transition probability function.

Rothman & Boughn consider whether it is possible to detect a single graviton and conclude that the answer is no when taking into account realistic physical conditions.

addrmf and XIS rmf

Using addrmf on the x*_segc_rmf_20051021.fit XIS response files causes an error message about a failure to close the first RMF. This occurs because these files have no EXTNAME keyword for the EBOUNDS extension. The error message is misleading and unnecessary so is fixed in addrmf version 1.20.

Keywords: HEAsoft, Suzaku