Bibcode
Branduardi-Raymont, G.; Mason, K. O.; Murdin, P. G.; Martin, C.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society (ISSN 0035-8711), vol. 216, Oct. 15, 1985, p. 1043-1055. SERC-supported research.
Fecha de publicación:
10
1985
Número de citas
26
Número de citas referidas
25
Descripción
A ≡7-hr observation of the central part of the Coma cluster of
galaxies has been performed with the EXOSAT LE telescopes and CMA
detectors. Five serendipitous sources are detected within the inner 35
arcmin radius of the field. Optical spectroscopy shows that four of
these are background AGN not associated with the cluster. At the
sensitivity level of the EXOSAT exposure, the authors would have
expected to detect only 0.01 background sources on the basis of the
Einstein Medium Sensitivity Survey. They discuss ways of interpreting
this result and in particular the possibility that the AGN detected in
the EXOSAT field have a much softer average X-ray spectrum than that
usually considered to be 'canonical'.