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AGNs among ROSAT Blank Field Sources
I. Cagnoni, M. Elvis, D. -W. Kim +3
We selected a sample of sources with high X-ray over optical flux ratio from the ROSAT PSPC archives. Out of the 16 sources in our sample, one is a (possibly extreme) BL Lac and tw…
1WGAJ1216.9+3743: Chandra Finds an Extremely Steep Ultraluminous X-ray Source
I. Cagnoni, R. Turolla, A. Treves +4
We report the discovery of a new ultraluminous X-ray source (ULX) in the nearby galaxy NGC 4244 from Chandra archival data. The source, 1WGAJ1216.9+3743, is one of the least lumino…
The Far Ultraviolet Spectroscopic picture of the Missing Baryons in the Local Group
F. Nicastro, A. Zezas, M. Elvis +6
The number of detected baryons in the low-redshift Universe (z < 1) is far small er than the corresponding number of baryons observed at higher redshift. According to hydrodynamica…
ROSAT Blank Field Sources I: Sample Selection and Archival Data
Ilaria Cagnoni, Martin Elvis, Dong-Woo Kim +2
We have identified a population of blank field sources (or `blanks') among the ROSAT bright unidentified X-ray sources with faint optical counterparts. The extreme X-ray over optic…
X-ray Arc Structures in Chandra Images of NGC5128 (Centaurus A)
M. Karovska, G. Fabbiano, F. Nicastro +3
We describe results from our initial study of the diffuse X-ray emission structures in NGC 5128 (Cen A) using the Chandra X-ray Observatory observations. The high-angular resolutio…
Chandra Discovery of a 300 kpc X-ray Jet in the GPS Quasar PKS1127-145
Aneta Siemiginowska, Jill Bechtold, Thomas L. Aldcroft +3
We have discovered an X-ray jet with Chandra imaging of the z=1.187 radio-loud quasar PKS1127-145. In this paper we present the Chandra X-ray data, follow-up VLA observations, and…