J/A+A/664/A158 Luminous and ultraluminous infrared galaxies (Reynolds+, 2022)
Energetic nuclear transients in luminous and ultraluminous infrared galaxies.
Reynolds T.M., Mattila S., Efstathiou A., Kankare E., Kool E., Ryder S.,
Pena-Monino L., Perez-Torres M.A.
<Astron. Astrophys. 664, A158 (2022)>
=2022A&A...664A.158R 2022A&A...664A.158R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, IR
Keywords: black hole physics - galaxies: starburst - galaxies: nuclei -
infrared: general
Abstract:
Energetic nuclear outbursts have been discovered in luminous and
ultraluminous infrared galaxies (U/LIRGs) at unexpectedly high rates.
To investigate this population of transients, we performed a search in
mid-IR data from the Wide-field Infrared Survey Explorer (WISE)
satellite and its NEOWISE survey to detect and characterise luminous
and smoothly evolving transients in a sample of 215 U/LIRGs. We report
three new transients, all with ΔL>1043erg/s, in addition to
two previously known cases. Their host galaxies are all part of major
galaxy mergers, and through radiative transfer model fitting we find
that all have a significant contribution from an active galactic
nucleus (AGN). We characterised the transients through measurements of
their luminosities and resulting energetics, all of which are between
1050.9erg and 1052.2erg. The IR emission of the five transients
was found to be consistent with re-radiation by the hot dust of
emission at shorter wavelengths, presumably originating from an
accretion event, onto the supermassive black hole. The corresponding
transient rate of (1.6-4.6)x10-3/yr/galaxy is over an order of
magnitude higher than the rate of large amplitude flares shown by AGN
in the optical. We suggest that the observed transients are part of a
dust-obscured population of tidal disruption events (TDEs) that have
remained out of the reach of optical surveys due to the obscuring
dust. In one case, this is supported by our radio observations. We
also discuss other plausible explanations. The observed rate of events
is significantly higher than optical TDE rates, which can be expected
in U/LIRG hosts undergoing a major galaxy merger with increased
stellar densities in the nuclear regions. Continued searches for such
transients and their multi-wavelength follow-up is required to
constrain their rate and nature.
Description:
The sample of U/LIRGs used for the study is presented in this table.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 67 275 Sample of U/LIRGs used for the study
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- RBGS RBGS name
18- 36 A19 --- AllWISE AllWISE name (JHHMMSS.ss+DDMMSS.s)
38- 45 F8.4 deg RAdeg Rigth ascension (J2000)
47- 54 F8.4 deg DEdeg Declination (J2000)
56- 61 F6.2 Mpc Dist Distance
63- 67 F5.2 [Lsun] LIR Infrared luminosity
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Acknowledgements:
Thomas M. Reynolds, treynolds1729(at)gmail.com
(End) Patricia Vannier [CDS] 22-Jul-2022