Chandra COSMOS Survey Analysis
Simonetta Puccetti (ASI Science Data Center (ASDC)-INAF) , on behalf of the C-Cosmos collaboration
The 1.8 Msec Chandra COSMOS Survey (C-COSMOS) is the largest Chandra GO program at the time of award. COSMOS is a pan-chromatic survey of the extragalactic sky designed to be both large and deep enough to study galaxy and quasar evolution in typical environments with minimal 'cosmic bias'. The location of COSMOS near the equator (10h +02deg) allows all major and future facilities (esp. EVLA, ALMA) to target this 2 sq. deg.region. Both space - HST, Spitzer, GALEX, XMM - and ground-based - VLA, Subaru, CTIO, KPNO, CFHT, Magellan, VLT - have already surveyed the area to faint limits. The central region of the COSMOS field observed in C-COSMOS is now the target of deeper surveys by the VLA and VLT, and proposed for GALEX and VISTA. We present the current status of the analysis of the C-COSMOS dataset. We focus on source detection and validation, which are complicated by the offset tiling structure of the survey. The 6x6 array of 50ksec observations gives a uniform 200ksec exposure, and a well-defined cut-off in flux. The depth of C-COSMOS was chosen to detect significant numbers of galaxies, up to z 0.9, comparable with the depth of the COSMOS galaxy surveys. About 2000 sources have been detected using both a wavelet algorithm and a PSF fitting algorithm. The present catalog includes about 100 sources with 0.5-2 keV flux smaller that 3E-16 cgs, one of the largest sample of faint X-ray sources so far. Particular care was put in the detection, validation and identification of sources with a separation <12" right down to the limit imposed by the Chandra PSF. This will allow us to put robust constraints on the X-ray source correlation function down to tens of kpc (for a typical z=1). Preliminary results on source number counts, cosmic variace and source clustering will be presented.