Ivison, R. J. and Page, M. J. and Cirasuolo, M. and Harrison, C. M. and Mainieri, V. and Arumugam, V. and Dudzevičiūtė, U. (2019) 'Hyperluminous starburst gives up its secrets.', Monthly notices of the Royal Astronomical Society., 489 (1). pp. 427-436.
HATLAS J084933.4+021443 was identified as a dusty starburst via its rest-frame far-infrared (far-IR) emission. Multi-frequency imaging and spectroscopy revealed a cluster of four dusty galaxies at z = 2.41, covering 80 kpc. Here, we use ALMA to confirm a more distant, fifth protocluster member, and present X-ray and rest-frame optical imaging spectroscopy of the brightest, an unlensed hyperluminous IR galaxy (HyLIRG). The data reveal broad Hα and bright [N II] lines, and bright X-ray emission, characteristics that betray a Type-1 active galactic nucleus (AGN), strengthening evidence that AGN are ubiquitous amongst HyLIRGs. The accreting black hole is super massive, Mbh ≈ 2 × 109 M⊙, with little intrinsic absorption, NH ≈ 5 × 1021 cm−2. The X-ray properties suggest the accretion luminosity rivals that of the starburst, yet it is not obvious where this emerges in its panchromatic spectral energy distribution (SED). We outline three scenarios that could give rise to the observed characteristics, and how we might distinguish between them. In the first, we see the AGN through the host galaxy because of the cavity it excavates. In the others, the AGN is not co-spatial with the starburst, having been ejected via asymmetric gravitational radiation, or having evolved towards the naked quasar phase in an unseen companion.
|Full text:||(AM) Accepted Manuscript|
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|Publisher Web site:||https://doi.org/10.1093/mnras/stz2180|
|Publisher statement:||This article has been accepted for publication in the Monthly notices of the Royal Astronomical Society ©: 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.|
|Date accepted:||26 July 2019|
|Date deposited:||13 August 2019|
|Date of first online publication:||08 August 2019|
|Date first made open access:||No date available|
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