Premium
Identification of a complete sample of northern ROSAT All‐Sky Survey X‐ray sources
Author(s) -
Zickgraf F.J.,
Pakull M. W.,
Krautter J.,
Appenzeller I.,
Thiering I.,
Voges W.,
Mujica R.,
Serrano A.,
Chavarria C.
Publication year - 1998
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.2123190121
Subject(s) - rosat , physics , astrophysics , galaxy
We report on the discovery of the rst z> 4 QSO in the ROSAT All Sky Survey (RASS) near the X-ray source RXJ1028.6 0844. From the Ly emission line found in an optical spectrum we measured z =4 :276 0:005. This is so far the hightest redshift for a QSO in the RASS. The RASS X-ray count rate of 0.035 ctss 1 leads to an X-ray flux of fx= 8.3310 13 ergs 1 cm 2 andaluminosityofLx 61046 ergs 1 in the 2 10keV rest frame energy band of the QSO if galactic column density of neutral hydrogen and a photon index = 2 isassumed.Thespectralenergydistributionasinferredfromthe observed hardness ratios indicates the presence of considerable intrinsic absorption in the QSO around 2 2:5keV.