AAS 197, January 2001
Session 40. REU: Instrumentation, Star Clusters and Galaxies
Display, Tuesday, January 9, 2001, 9:30am-7:00pm, Exhibit Hall

## [40.12] An Analysis of Point Sources in Two {\em Chandra} Deep Fields

D.L. Freedman (Princeton), J.M. Vrtilek, W.R. Forman, C. Jones, S. Virani, L. Grego, L.P. VanSpeybroeck (SAO)

We study the discrete point sources in two deep {\em Chandra} observations in order to determine their distribution and spectral properties. In one observation of 120 ksec, identified by the inclusion of the cluster MS1137.5+6625, we detected 130 point sources. In a combined 190 ksec observation of the field that includes the cluster CL0848.6+4453 we found 135 point sources. Plots of \log N - \log S for both fields showed a gradual flattening of the slope toward fainter fluxes, indicating that the number of sources per square degree with smaller fluxes is increasing less rapidly than at higher fluxes. In addition, we determined the average spectra for point sources as a function of the point source flux. The photon index of the spectra decreased as the fluxes of the sources in the group decreased, i.e., source spectra hardened at fainter fluxes.

D.L.F. gratefully acknowledges support from the NSF-REU program and from the SAO.