NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-18 T12:54:05 PDT
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For refcode 2009ApJ...690..267D:
Retrieve 64 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
2009ApJ...690..267D Candidate Active Nuclei in Late-Type Spiral Galaxies Desroches, Louis-Benoit; Ho, Luis C. Abstract. We have assembled a sample of 64 late-type spiral galaxies (T types 6.0-9.0, corresponding to Hubble types Scd-Sm) with archival Chandra data. At a signal-to-noise (S/N) threshold of 3, we find 12 objects with X-ray point-source detections in close proximity with the optical or near-infrared position of the nucleus (median offset delta = 1farcs6), suggestive of possible low-luminosity active galactic nuclei (AGNs). Including measurements with 3 > S/N > 1.5, our detections increase to 18. These X-ray sources range in luminosity from L_X_(2-10 keV) = 10^37.1^ to 10^39.6^ erg s^-1^. Considering possible contamination from low-mass X-ray binaries (LMXBs), we estimate that ~5 detections are possible LMXBs instead of true AGNs, based on the probability of observing an LMXB in a nuclear star cluster (NC) typically found in these late-type spiral galaxies. Given the typical ages of NCs, contamination by high-mass X-ray binaries is unlikely. This AGN fraction is higher than that observed in optical surveys, indicating that active nuclei, and hence central black holes (BHs), are more common than previously suggested. The incidence of AGN activity in such late-type spiral galaxies also suggests that nuclear massive BHs can form and grow in galaxies with little or no evidence for bulges. Follow-up multiwavelength observations will be necessary to confirm the true nature of these sources. Key words: galaxies: active, galaxies: nuclei, galaxies: Seyfert, galaxies: statistics, X-rays: galaxies
Retrieve 64 NED objects in this reference.
Please click here for ADS abstract

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