AAS 205th Meeting, 9-13 January 2005
Session 143 Quasars
Poster, Thursday, January 13, 2005, 9:20am-4:00pm, Exhibit Hall

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[143.06] Chandra Discovery of an X-ray cluster at redshift 1

S. LaMassa, A. Siemiginowska, T. Aldcroft (Harvard-Smithsonian Center for Astrophysics), J. Bechtold (Steward Observatory, University of Arizona), D. Burke (Harvard-Smithsonian Center for Astrophysics)

We report the discovery of an X-ray cluster at redshift z = 1.063 associated with the Compact Steep Spectrum radio loud quasar Q0740+380. We present the analysis of the Chandra data including modeling of the extended emission. The PSF data were plotted against the source data to gauge the range of the extended emission around the quasar. The extended region, spanning from 2.7 arcseconds to 13 arcseconds, was then broken into 4 sectors in 90 degree intervals. Analysis of these sectors included finding the number of counts (total, hard, and soft) as well as spectroscopy. The differences in counts among the sectors indicate a significant variation of luminosity and surface brightness. By using a combination of a raymond plasma and absorption models, the temperatures for each region were fit, revealing slight differentiation among sectors. However the significance of these differences is low due to our signal-to-noise ratio.

Diffuse X-ray cluster emission is detected up to ~ 100~kpc from the quasar and contains 651.5±36.9 net counts. The X-ray spectrum shows a strong Fe-line emission with EW=400eV at the quasar redshift and confirms the thermal nature of this diffuse component. We obtain the temperature of 3.26+0.5-0.43~keV and X-ray luminosity L0.5-2~keV~3 * 1044ergs~s-1 of this cluster emission which is in agreement with the cluster's luminosity-temperature relation.

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© 2004. The American Astronomical Society.