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Chandra X-ray observations of the hyper-luminous infrared galaxy IRAS F15307+3252

Chandra X-ray observations of the hyper-luminous infrared galaxy IRAS F15307+3252
Chandra X-ray observations of the hyper-luminous infrared galaxy IRAS F15307+3252
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.
1745-3925
2223-2233
Hlavacek-Larrondo, J.
aa5e6656-22ed-40fe-a792-edc358c7f7a6
Gandhi, P.
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Hogan, M.T.
884765f3-3b4a-4305-9c71-65579b9c4c6d
Gendron-Marsolais, M-L.
9b5977c9-38ed-48ae-b27a-473f4dbc36f6
Edge, A.C.
95404fee-64b0-4cbd-8bba-6ab2dfafa9e2
Fabian, A.C.
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Russell, H.R.
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Iwasawa, K.
1ff1acf1-ffb6-4101-b22a-952f10f9fdec
Hlavacek-Larrondo, J.
aa5e6656-22ed-40fe-a792-edc358c7f7a6
Gandhi, P.
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Hogan, M.T.
884765f3-3b4a-4305-9c71-65579b9c4c6d
Gendron-Marsolais, M-L.
9b5977c9-38ed-48ae-b27a-473f4dbc36f6
Edge, A.C.
95404fee-64b0-4cbd-8bba-6ab2dfafa9e2
Fabian, A.C.
0c353376-f159-4129-b03e-d3993c0c5406
Russell, H.R.
8e75764e-d968-4041-8304-97c04175833e
Iwasawa, K.
1ff1acf1-ffb6-4101-b22a-952f10f9fdec

Hlavacek-Larrondo, J., Gandhi, P., Hogan, M.T., Gendron-Marsolais, M-L., Edge, A.C., Fabian, A.C., Russell, H.R. and Iwasawa, K. (2017) Chandra X-ray observations of the hyper-luminous infrared galaxy IRAS F15307+3252. Monthly Notices of the Royal Astronomical Society: Letters, 464 (2), 2223-2233. (doi:10.1093/mnras/stw2468).

Record type: Article

Abstract

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.

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Accepted/In Press date: 23 September 2016
e-pub ahead of print date: 28 September 2016
Published date: 11 January 2017
Organisations: Astronomy Group

Identifiers

Local EPrints ID: 402995
URI: http://eprints.soton.ac.uk/id/eprint/402995
ISSN: 1745-3925
PURE UUID: 49ec1bb2-6d6f-4e89-afe8-dcfcb25e86e6
ORCID for P. Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

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Date deposited: 21 Nov 2016 14:56
Last modified: 07 Oct 2020 02:06

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