Search for GRB afterglows in the ROSAT all-sky survey

We report on the status of our search for X-ray afterglows of gamma-ray bursts (GRBs) using the ROSAT all-sky survey data. The number of potential X-ray afterglow candidates with respect to the expected number of beamed GRBs allows to constrain the relative beaming angles of GRB emission and afterglow emission at about 1-5 hrs after the GRB.Comment: 3 pages A&A style, 1 color ps-figure; To appear in A&A Suppl. Series, Proc. of Rome 1998 GRB workshop, also available from http://www.aip.de/~jcg/publis.htm

ROSAT All-Sky Survey observations of IRAS galaxies; I. Soft X-ray and far-infrared properties

The 120,000 X-ray sources detected in the RASS II processing of the ROSAT All-Sky Survey are correlated with the 14,315 IRAS galaxies selected from the IRAS Point Source Catalogue: 372 IRAS galaxies show X-ray emission within a distance of 100 arcsec from the infrared position. By inspecting the structure of the X-ray emission in overlays on optical images we quantify the likelihood that the X-rays originate from the IRAS galaxy. For 197 objects the soft X-ray emission is very likely associated with the IRAS galaxy. Their soft X-ray properties are determined and compared with their far-infrared emission. X-ray contour plots overlaid on Palomar Digitized Sky Survey images are given for each of the 372 potential identifications. All images and tables displayed here are also available in electronic form.Comment: accepted for publication in A&AS, complete version including all figures and tables available at http://www.rosat.mpe-garching.mpg.de/~bol/iras_rassI

Investigating ionized disc models of the variable narrow-line Seyfert 1 PG 1404+226

We investigate the use of relativistically blurred photoionized disc models on an XMM-Newton observation of the Narrow Line Seyfert 1 galaxy PG 1404+226. The model is designed to reproduce the radiation from the inner accretion disc around a Kerr black hole, and is more successful at fitting the spectrum than models based on a thermal soft excess. The source varies strongly over the course of the observation, and the disc model works over all observed flux states. We conclude that it is a useful tool in the study of certain quasars.Comment: 6 pages, 3 figures. Accepted for publication in MNRA