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The mid-infrared and CO gas properties of an extreme star-forming FeLoBAL quasar

L. K. Pitchford, D. Farrah, K. Alatalo, J. Afonso, A. Efstathiou, E. Hatziminaoglou, M. Lacy, T. Urrutia, G. Violino

Abstract
We present a detailed study of a high-redshift iron low-ionization broad absorption line (FeLoBAL) quasar (SDSS1214 at z = 1.046), including new interferometric 12CO J = 2–1 observations, optical through far-infrared photometry, and mid-infrared spectroscopy. The CO line is well fit by a single Gaussian centred 40 km s−1 away from the systemic velocity and implies a total molecular gas mass of Mgas=7.3×1010M⁠. The infrared spectral energy distribution requires three components: an active galactic nucleus (AGN) torus, an AGN polar dust component, and a starburst. The starburst dominates the infrared emission with a luminosity of log(LSB[L⊙])=12.91+0.02−0.02⁠, implying a star formation rate of about 2000 M⊙yr−1, the highest known among FeLoBAL quasars. The AGN torus and polar dust components are less luminous, at log(LAGN[L])=12.36+0.14−0.15 and log(Ldust[L])=11.75+0.26−0.46⁠, respectively. If all of the molecular gas is used to fuel the ongoing star formation, then the lower limit on the subsequent duration of the starburst is 40 Myr. We do not find conclusive evidence that the AGN is affecting the CO gas reservoir. The properties of SDSS1214 are consistent with it representing the endpoint of an obscured starburst transitioning through a LoBAL phase to that of a classical quasar.

Keywords
galaxies: active; quasars: general; radio lines: ISM; Astrophysics - Astrophysics of Galaxies

Monthly Notices of the Royal Astronomical Society
Volume 487, Issue 3, Page 3130
2019 August

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia