Roy E. Kilgard

Chandra and Spitzer Unveil Heavily Obscured Quasars in the Chandra/SWIRE Survey*

Using the large multi-wavelength data set in the chandra/SWIRE Survey (0.6 square degrees in the Lockman Hole), we show evidence for the existence of highly obscured (Compton-thick) AGN, estimate a lower limit to their surface density and characterize their multi-wavelength properties. Two independent selection methods based on the X-ray and infrared spectral properties are presented. The two selected samples contain 1) 5 X-ray sources with hard X-ray spectra and column densities > 10^24 cm-2, and 2) 120 infrared sources with red and AGN-dominated infrared spectral energy distributions (SEDs). We estimate a surface density of at least 25 Compton-thick AGN per square degree detected in the infrared in the chandra/SWIRE field of which ~40% show distinct AGN signatures in their optical/near-infrared SEDs, the remainings being dominated by the host-galaxy emission. Only ~33% of all Compton-thick AGN are detected in the X-rays at our depth (F(0.3-8 keV)>10^-15 erg/cm2/s. We report the discovery of two sources in our sample of Compton-thick AGN, SWIRE_J104409.95+585224.8 (z=2.54) and SWIRE_J104406.30+583954.1 (z=2.43), which are the most luminous Compton-thick AGN at high-z currently known. The properties of these two sources are discussed in detail with an analysis of their spectra, SEDs, luminosities and black-hole masses.

Chandra High-Resolution Camera observations of the luminous X-ray source in the starburst galaxy M82

We have analyzed Chandra High Resolution Camera observations of the starburst galaxy M82, concentrating on the most luminous x-ray source. We find a position for the source of

THE ORBITAL PERIOD OF THE WOLF-RAYET BINARY IC 10 X-1: DYNAMIC EVIDENCE THAT THE COMPACT OBJECT IS A BLACK HOLE

\rm R.A. = 09^h 55^m 50^s.2, decl. = +69^{\circ} 40\arcmin 46\arcsec.7

A Minisurvey of X-Ray Point Sources in Starburst and Nonstarburst Galaxies

(J2000) with a

CLASSIFYING X-RAY SOURCES IN EXTERNAL GALAXIES FROM X-RAY COLORS

1\sigma

The Redshift of the Optical Transient Associated with GRB 010222

radial error of

Chandra monitoring observations of the ultraluminous X-ray source NGC 5204 X-1

0.7\arcsec

A Chandra Survey of Nearby Spiral Galaxies. I. Point Source Catalogs

. The accurate x-ray position shows that the luminous source is not at the dynamical centre of M82 nor coincident with any suggested radio AGN candidate. The source is highly variable between observations, which suggests that the source is a compact object and not a supernova or remnant. There is no significant short term variability within the observations. Dynamical friction and the off-center position place an upper bound of

M74 X-1 (CXOU J013651.1+154547): AN EXTREMELY VARIABLE ULTRALUMINOUS X-RAY SOURCE

10^{5} - 10^{6} M_{\odot}

An XMM–Newton view of M101 – I. The luminous X-ray source population

on the mass of the object, depending on its age. The x-ray luminosity suggests a compact object mass of at least