X-ray Source-Galaxy Angular Cross-Correlation function in the COSMOS Field Takamitsu Miyaji, Richard E. Griffiths (Carnegie Mellon Univ.) COSMOS XMM-Newton Team et al.

Motivation How do AGNs trace the large scale structure of the Universe, what is the environment of AGN activity? Is there any difference between obscured and unobscured AGN in terms of the environment that they sit in? --- (Another test for the simplest AGN Unified scheme.) X-ray sources detected in the hard band are more strongly clustered than the soft sample (Yang et al. 03), in the projected space. (Real difference in clustering properties or difference in redshift distribution?) Cross-correlation with galaxies give much better signal- to-noise ratio than X-ray source auto-correlation sample.

Why Cross-Correlation with Galaxies? ● Bias parameter of absorbed/unabsorbed AGNs b X ~(  X / )/ (  DM / ) ● Simplest biased scheme:  XG ~b X b G  DM ; b-bias parameters ● Correlating AGNs with numerous galaxies is advantageous over X-ray source ACF because of the sheer number of correlating partner. ● Correlating with galaxies with thick redshift cuts in photo-z catalog will gives redshift-dependent information (even before the redshifts of X-ray sources are known).

XMM-Newton Data (18 fields)

Making Uniform X-ray Samples from XMM-Newton  Use offaxis<12.5 arcmin to avoid distorted PSF  Preliminary source detection by wavelet, independent from the MPE effort. Extended sources are excluded from the samples. (The MPE version involves sliding box detection in combination with multi-source maximum-likelihood fitting using model PSFs, that I would like to use for final results.)  As a first approximation, Count rate vs Exposure Cuts to create homogeneous sample.

Making Uniform X-ray Samples Exposure [s] Count Rate

Current Uniform X-ray Source Samples  These requirements limit the region of analysis to ~1 deg 2 currently.  Soft sample: >~1.2x erg s -1 cm -2 (05-2 keV), 527 source  Hard sample: >~8x erg s -1 cm -2 (2-10 keV), 276 sources

Quick and Dirty Results – Auto- correlation of X-ray Sources W(  )=(D X D X -2R X D X +R X R X )/R X R X D X :X-ray Source Sample R X :Randomized X-ray Source sample Errors corresponds to 1 sigma dispersion of 100 different random samples. Area: ~1 deg 2 Small-scale negative value --- Source confusion/wavelet detection artifact. Better source detection (Multi-source maximum-likelihood) will improve. High-res X-ray image with Chandra!!!

Quick and Dirty Results - Cross- correlation W(  )=D X D G /R X D G -1 D X :X-ray Source Sample D O :Galaxy Sample R X :Randomized X-ray Source sample Updating to Landy & Szalay estimator in progress. W(  )=(D X D G -D x R G -R X D G - R X R G )/R X R G Area: ~1 deg 2 Optical sample: April version of Mobasher Photo-z catalog ( 17<r'<25.0)

To Do List ● Implement Landy & Szalay estimator for CCF. ● Use and evaluate resampling error estimate methods (Jackknife/Bootstrap). ● Improvements in source detection and investigate carefully on sample uniformity. ● At least a few times more X-ray sources can be used after all the XMM-Newton data are in. ● Fitting to smooth functions. ● De-project with limber’s equation to obtain correlation lengths. Good redshift-distributions of X-ray sources (e.g. from XLF) and photo-z cut galaxy samples needed.

Need Help!!! ● Thorough study of photometric redshift catalog. Uniformity, magnitude thresholds, region masks. ● X-ray source redshift can be exploited using photo-z also to make redshift cuts to the X-ray sources. Improving photo-z using Galaxy+AGN templates would be very helpful. ● Official version of XMM-Newton source list, exposure maps etc…