Chandra X-ray observations of the hyper-luminous infrared galaxy IRAS F15307+3252
Hlavacek-Larrondo, J.; Gandhi, P.; Hogan, M.T.; Gendron-Marsolais, M.-L.; Edge, A.C.; Fabian, A.C.; Russell, H.R.; Iwasawa, K.; Mezcua, M.
Professor Alastair Edge firstname.lastname@example.org
Hyper-luminous infrared galaxies (HyLIRGs) lie at the extreme luminosity end of the IR galaxy population with LIR > 1013 L⊙. They are thought to be closer counterparts of the more distant sub-millimeter galaxies, and should therefore be optimal targets to study the most massive systems in formation. We present deep Chandra observations of IRAS F15307+3252 (100 ks), a classical HyLIRG located at z = 0.93 and hosting a radio-loud AGN (L1.4 GHz ∼ 3.5 × 1025 W Hz−1). The Chandra images reveal the presence of extended (r = 160 kpc), asymmetric X-ray emission in the soft 0.3–2.0 keV band that has no radio counterpart. We therefore argue that the emission is of thermal origin originating from a hot intragroup or intracluster medium virializing in the potential. We find that the temperature (∼2 keV) and bolometric X-ray luminosity (∼3 × 1043 erg s−1) of the gas follow the expected LX-ray–T correlation for groups and clusters, and that the gas has a remarkably short cooling time of 1.2 Gyr. In addition, VLA radio observations reveal that the galaxy hosts an unresolved compact steep-spectrum (CSS) source, most likely indicating the presence of a young radio source similar to 3C186. We also confirm that the nucleus is dominated by a redshifted 6.4 keV Fe Kα line, strongly suggesting that the AGN is Compton-thick. Finally, Hubble images reveal an overdensity of galaxies and sub-structure in the galaxy that correlates with soft X-ray emission. This could be a snapshot view of on-going groupings expected in a growing cluster environment. IRAS F15307+3252 might therefore be a rare example of a group in the process of transforming into a cluster.
Hlavacek-Larrondo, J., Gandhi, P., Hogan, M., Gendron-Marsolais, M., Edge, A., Fabian, A., …Mezcua, M. (2017). Chandra X-ray observations of the hyper-luminous infrared galaxy IRAS F15307+3252. Monthly Notices of the Royal Astronomical Society, 464(2), 2223-2233. https://doi.org/10.1093/mnras/stw2468
|Journal Article Type||Article|
|Acceptance Date||Sep 27, 2016|
|Online Publication Date||Sep 28, 2016|
|Publication Date||Jan 11, 2017|
|Deposit Date||Apr 28, 2017|
|Publicly Available Date||May 4, 2017|
|Journal||Monthly Notices of the Royal Astronomical Society|
|Publisher||Royal Astronomical Society|
|Peer Reviewed||Peer Reviewed|
|Related Public URLs||arxiv.org/pdf/1606.07818.pdf|
Published Journal Article
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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