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Astron. Astrophys. 319, 33-44 (1997)

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Identification of X-ray sources <1° from Seyfert galaxies

H. Arp

Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85740 Garching, Germany

Received 25 March 1996 / Accepted 15 May 1996


Excess numbers of X-ray sources around bright Seyfert galaxies have been demonstrated with significances of association up to 7.4 sigma (Radecke, preceding paper). The optical identification of these sources is shown here to be predominantly blue stellar objects (BSO's) of which some are already catalogued as quasars.

Excluding the two brightest Seyferts, a subset of 24 with apparent magnitudes between [FORMULA] show a minimum excess of [FORMULA] bright X-ray sources. These excess X-ray sources are generally distributed between [FORMULA] and 12 of the Seyferts show conspicuous pairs of X-ray sources across their active nuclei. Additional pairing and alignment of sources is seen for the remaining Seyferts. Among the paired X-ray sources, 53 have been identified as BSO's.

Some double and multiple BSO's have been identified which are candidates for groups and associations of quasars. Some groups are well aligned and some centered on small blue galaxies.

Four previously known BL Lac objects fall close enough to the Seyferts in this sample to confirm, at a significance level of [FORMULA], a previously reported association of BL Lac objects with bright, low redshift galaxies.

Key words: galaxies: Seyfert; BL Lac Objects – quasars: general – X-rays: galaxies

Send offprint requests to: H. Arp

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© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998