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.