2015MNRAS.454.3722S -
Mon. Not. R. Astron. Soc., 454, 3722-3742 (2015/December-3)
The search for active black holes in nearby low-mass galaxies using optical and mid-IR data.
SARTORI L.F., SCHAWINSKI K., TREISTER E., TRAKHTENBROT B., KOSS M., SHIRAZI M. and OH K.
Abstract (from CDS):
We investigated AGN activity in low-mass galaxies, an important regime that can shed light on to black hole (BH) formation and evolution, and their interaction with their host galaxies. We identified 336 AGN candidates from a parent sample of ∼ 48000 nearby low-mass galaxies (M* ≤ 109.5M☉, z < 0.1) in the Sloan Digital Sky Survey. We selected the AGN using the classical BPT diagram, a similar optical emission line diagnostic based on the He II\: λ4686 line, and mid-IR colour cuts. Different criteria select host galaxies with different physical properties such as stellar mass and optical colour and only 3 out of 336 sources fulfil all three criteria. This could be in part due to selection biases. The resulting AGN fraction of ∼ 0.7 percent is at least one order of magnitude below the one estimated for more massive galaxies. At optical wavelengths, the He II\:-based AGN selection appears to be more sensitive to AGN hosted in star-forming galaxies than the classical BPT diagram, at least in the low-mass regime. The archival X-ray and radio data available for some of the AGN candidates seem to confirm their AGN nature, but follow-up observations are needed to confirm the AGN nature of the rest of the sample, especially in the case of mid-IR selection. Our sample will be important for future follow-up studies aiming to understand the relation between BHs and host galaxies in the low-mass regime.
Abstract Copyright:
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
Journal keyword(s):
galaxies: active - galaxies: dwarf - galaxies: nuclei - galaxies: Seyfert - infrared: galaxies
VizieR on-line data:
<Available at CDS (J/MNRAS/454/3722): tablea1.dat tablea2.dat tablea3.dat tablea4.dat tablea5.dat tablea6.dat tablea7.dat>
Simbad objects:
337
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