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Nuclear X‐ray sources in nearby galaxies
Author(s) -
Roberts T. P.,
Warwick R. S.
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.2123190117
Subject(s) - citation , library science , physics , galaxy , astronomy , computer science
The “search for dwarf Seyfert nuclei” of Ho e t al. (1995; 1997) bas resulted in the publication of a statistically complete sample of N 470 spectrally classified nearby galaxy nuclei (hereafter referred to as the HFS sample). The demographics of this sample show that 11% of nearby galaxies have a Seyfert-type nucleus, 33% harbour a Low Ionisation Nuclear Emission-line Region (LINER) and 42% have a nucleus characterised by HI1 emission. The remainder of the galaxies showed no nuclear optical emission lines (NOEL). Here, we present the initial results of an examination of the X-ray properties of the HFS sample. This has been achieved by crosscorrelating the HFS sample with the WGACAT (White et al. 1994), a catalogue of the soft X-ray sources detected in the pointed observation phase of the ROSAT PSPC. Though this catalogue has incomplete sky coverage and a bias towards observations of AGN, the results of the correlation still allow us to discern possible trends in the X-ray properties of the sub-samples and to identify individual sources of potential interest. We have only considered WGACAT sources within the central 18’ radius of the PSPC detector and observations with at least 8 ks integration time. This reduced catalogue was cross-correlated with the HFS galaxies, and a total of 58 coincidences of an X-ray source within 30’’ of a galactic nucleus were found. A further 7 HFS galaxies within PSPC fields were not detected; a 95% upper limit on their nuclear X-ray flux was found by inspection of archival data.