Monday, January 31, 2005


Aloisio et al. review tests for quantum gravity based on observations of high energy particles.

Diemand et al. use supercomputer simulations of the concordance model to argue that the first structures formed have Earth mass and Solar System size. Such structures are stable enough to have survived and there should be 1e15 within the Galactic Halo with one passing through the Solar System every few thousand years.

Keywords: quantum gravity, dark matter, cosmology


Li-Xin Li sends me a couple of bug fixes for their kerrbb model, available from the additional models webpage. The problem was spotted by Shane Davis at UCSB. I updated the relevant

Keywords: xspec

Wednesday, January 26, 2005


Takizawa uses 3-D hydro simulations to investigate turbulence generation by substructure moving through the ICM.

Brusa et al. stack Chandra deep survey sources in redshift bins and find ubiquitous Fe lines out to z~3 in agreement with XRB synthesis models.

Keywords: clusters, AGN

Tuesday, January 25, 2005


Kravtsov et al. use N-body+gas dynamics simulations to investigate the effect of dissipation on the baryon fraction in clusters.

Soltan et al. cross-correlate the soft X-ray background (using ROSAT and XMM) with the positions of galaxies and detect a signal out to at least 1.5 Mpc. They interpret this as evidence for the WHIM since the signal is only seen at low energies.

Badenes et al. calculate X-ray emission spectra for shocked ejecta in SNIa.

Lui et al. find an HST counterpart for the ULX in NGC5204. The UV spectrum suggests a B0 1b supergiant overflowing its Roche lobe onto a compact primary.

Morris & Fabian analyse XMM observations of Abell 2597 and find evidence for a classical cooling flow with a rate of 100 solar masses/year.

Jeltema et al. use Chandra studies of clusters to investigate the evolution of structure with redshift. As expected they find higher redshift clusters to contain more substructure.

Hansen argues that temperatures observed in clusters are not true thermodynamic temperatures but are biassed by long-range interactions (eg gravity). The true temperature can be extracted from the spectrum or spectral line shapes.

Keywords: clusters, XRB, ULX, SNIa

Monday, January 24, 2005

hht5 continued

Continued working on the HHT code.
1) Split the pre-conditioning part into a separate routine (Precondition) in the file precond.c
2) Fixed bug that dat0[] array was not set to initial dat[] array if pre-conditioning was not used.
3) Reworked the separate pwr3b2a program which creates the marginal power spectrum. This was very inefficient - now runs much faster.

Keywords: HHT

Thursday, January 20, 2005


Working on John Cannizzo's Hilbert-Huang Transform program. First steps :
1) Split sifting code out into a separate file (sift.c). Create a header file (hht.h) with global definitions and useful parameters.
2) Extract spline fitting of envelope into its own routine to remove duplication of code for the upper and lower envelopes. Reduce number of arrays used in sifting and size them dynamically to the input data. Note that all arrays in the program number from 1 not 0 so all sizes have to be one larger than you think.
3) Optimize spline interpolations by modifying Press et al. splint routine to work with an input array assumed to be ordered the same way as the spline day. This speeds up the program by factor of ~2 as bisection search is only run for the first point to be interpolated.
4) Caught minor bug when the number of extrema in an envelope is 1. The extra points added to the end of the extrema data to stabilise the spline were given random values in this case. Changed this to set Deld{L/U}1 to time{L/U}[1] and Deld{L/U}2 to dat{L/U}[1] which seems the only reasonable case.
5) Using 1/f noise file confirmed that the new and old routines give identical results for time series with 16384 points.

Keywords: HHT

Tuesday, January 18, 2005

Seg fault from fakeit none

Jeremy Sanders produced a seg fault in xspec when running 'fakeit none none none none' when no datasets had been read in. He tracked this down to an error in allocating memory for a string in fakeit.c. Fixed this as 11.3.1t.

NB Jeremy used valgrind to check the memory useage. Looks like a useful Linux tool for memory checking and profiling.

Keywords: xspec

Saturday, January 15, 2005

Unitialized variables in xspec

Jeremy Sanders pointed out that xgtrl4 requires idelim to be set on input. Fixed this in
COSMO/setcsm.f, COMMAND/idntfy.f, DATA/calflx.f, pkrsid.f, FIT/gtearg.f, gtftar.f, setsys.f, stppar.f, MCMC/margin.f. I don't think this every made any difference.

Keywords: xspec


Modified rdhis.f to remove the VMS Fortran structures. This is for benefit of the JPL/LSU BATSE occultation team who are moving their system from VMS to Linux.

In testing found a minor bug in MODEL_PARAM/wprhis.f which was not writing the value of the parameters.

Keywords: heasoft, xspec

Thursday, January 13, 2005

Swift flickering pixel cleaning in xselect

The cleansis command in xselect works for other instruments than ASCA SIS - I turned the check off some time ago. The current xselect.mdb has SWIFT:ccol set to Amp. This doesn't work in cleansis because it passes Amp as the chipcol parameter and the event file has no TLMIN/MAX for this column. Examination of the event file shows Amp is uniformly equal to 1 so not sure why it is here anyway. The simplest solution is to switch SWIFT:ccol to NONE.

Keywords: heasoft, xselect

More on cleansis

Improved the error handling if TLMIN/MAX are missing for the RAWX/Y or chip columns. The error message was not written and program execution (incorrectly) continued.

Keywords: heasoft, cleansis

xselect documentation

Martin Still noticed that "set xysize" and "set xycenter" were missing from the xselect documentation. Modified xsel.tex to correct this.

Keywords: heasoft, xselect


Eisenstein et al. detect the first acoustic peak in the baryon distribution using the large scale correlation function from the spectroscopic SDSS sample of 46,748 luminous red galaxies. This provides the absolute distance to z=0.35 to an accuracy of 5% and confirms the standard cosmology parameters.

Bruggen et al. examine the effects on the ICM of AGN blowing bubbles using the 3-D FLASH code. Viscous and conductive dissipation distribute mechanical energy. They present synthetic Chandra observations.

Fabian et al. discuss viscous and conductive dissipation of sound waves in the ICM. They argue that this mechanism is most effective above 10^K thus allowing normal galaxy formation to proceed but stifling the growth of very massive galaxies.

Keywords: clusters, cosmology

Wednesday, January 12, 2005


Brandt and Hasinger review deep survey results from Chandra and XMM-Newton.

Norris discusses the management of astronomy data.

Zane and Turolla argue that there is evidence for a patchy surface temperature distribution on neutron stars and consider the theoretical and observational implications.

Fruscione et al. summarize the results of 1.5 years of XMM monitoring of NGC 4258 and combine with Chandra, ASCA and SAX archival data to give a nine-year time series of spectral changes. They argue that absorption changes are due to inhomogeneities in the warped rotating disk.

Ross and Fabian provide a wide-range of ionized reflection calculations available as a model REFLION for xspec.

McCarthy et al. explain the power-law entropy profiles in the cores of some massive cooling flows in the context of the Bertschinger (1989) cooling wave model. They find the the entropy profile depends only on the gravitational potential and the cooling function and propose this as a new way to measure the gravitational potential profile.

D'Agostino discusses hypothesis testing in the context of frequentist and Bayesian reasoning.

Keywords: AGN, neutron stars, clusters, statistics

WCSNAMEP in extractor output

Added WCSNAMEP keywords for image and WMAP output from extractor. This is the correct standard keyword for physical coordinates as opposed to the WCSTY1/2P keywords I picked up from the Chandra images. (extractor v4.51)

Keyword: heasoft, extractor

Thursday, January 06, 2005


Checked in a new version of the ASCA cleansis tool to remove hot and flickering pixels. This now works for other instruments with different numbers of CCD chips and image sizes. If the instrument has only one chip (as Swift XRT) then the chipcol parameter should be set to NONE.

One issue outstanding is that the number of chips is deduced from the TLMIN/MAX keywords of the chipcol column. If events have been selected from a subset of chips then cleansis will still try to work on all the chips containing no events. This doesn't produce a problem but does make the screen summary output a bit ugly.

Keywords: heasoft

Seager: Towards a Physical Characterization of Extrasolar Planets

Seminar by Sara Seager from DTM on the extrasolar planets. About 130 now known, most discovered using radial velocity method. Now 7 transiting planets - three are new class of very hot Jupitors. All are H/He gas giants. Two (including best studied HD209...) have large radii for their mass. Some sort of internal heating possibly due to another planet pumping their eccentricity then tidal heating. Programs to do transmission, absorption, and reflection spectroscopy of the planetary atmosphere by looking at primary and secondary eclipses.

Lots of work going on characterizing Earth as an extrasolar planet - observations of Earthshine to get spectrum of whole Earth. Work now extending to considering other "Earths" - only bacteria, pangea, slowing rotation,...

Monday, January 03, 2005


Vaughan et al. give a simple test for periodicity in data with red noise.

Keywords: statistics