Mon. Not. R. Astron. Soc., 492, 2268-2284 (2020/February-3)
X-ray detected AGN in SDSS dwarf galaxies.
BIRCHALL K.L., WATSON M.G. and AIRD J.
Abstract (from CDS):
In this work we present a robust quantification of X-ray selected AGN in local (z <= 0.25) dwarf galaxies (M* ≤3 ×109^M☉). We define a parent sample of 4331 dwarf galaxies found within the footprint of both the MPA-JHU galaxy catalogue (based on SDSS DR8) and 3XMM DR7, performed a careful review of the data to remove misidentifications and produced a sample of 61 dwarf galaxies that exhibit nuclear X-ray activity indicative of an AGN. We examine the optical emission line ratios of our X-ray selected sample and find that optical AGN diagnostics fail to identify 85 per cent of the sources. We then calculated the growth rates of the black holes powering our AGN in terms of their specific accretion rates (∝ LX/M*, an approximate tracer of the Eddington ratio). Within our observed sample, we found a wide range of specific accretion rates. After correcting the observed sample for the varying sensitivity of 3XMM, we found further evidence for a wide range of X-ray luminosities and specific accretion rates, described by a power law. Using this corrected AGN sample we also define an AGN fraction describing their relative incidence within the parent sample. We found the AGN fraction increases with host galaxy mass (up to ≃6 per cent) for galaxies with X-ray luminosities between 1039 and 1042 erg s–1, and by extrapolating the power law to higher luminosities, we found evidence to suggest the fraction of luminous AGN (LX ≥1042.4 erg s–1) is constant out to z ≃ 0.7.
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
galaxies: active - galaxies: dwarf - X-rays: galaxies
Status at CDS:
// Tables of objects will be appraised for possible ingestion in SIMBAD.
Misprints in Table B1: SDSS J112830.77+533005.2 = SDSS J112830.77+583342.9 ; 2MASS J08320052+1912058 = 2MASS J08320053+1912058.
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