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UV-luminous, star-forming hosts of z ~ 2 reddened quasars in the Dark Energy Survey

Published version
Peer-reviewed

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Authors

Wethers, CF 
Hewett, PC 
Lemon, CA 
McMahon, RG 

Abstract

We present the first rest-frame UV population study of 17 heavily reddened, high-luminosity (E(B-V)QSO 0.5; Lbol> 1046ergs−1) broad-line quasars at 1.5<z<2.7. We combine the first year of deep, optical, ground-based observations from the Dark Energy Survey (DES) with the near infrared VISTA Hemisphere Survey (VHS) and UKIDSS Large Area Survey (ULAS) data, from which the reddened quasars were initially identified. We demonstrate that the significant dust reddening towards the quasar in our sample allows host galaxy emission to be detected at the rest-frame UV wavelengths probed by the DES photometry. By exploiting this reddening effect, we disentangle the quasar emission from that of the host galaxy via spectral energy distribution (SED) fitting. We find evidence for a relatively unobscured, star-forming host galaxy in at least ten quasars, with a further three quasars exhibiting emission consistent with either star formation or scattered light. From the rest-frame UV emission, we derive instantaneous, dust-corrected star formation rates (SFRs) in the range 25 < SFRUV < 365 Myr−1, with an average SFRUV = 130 ± 95 Myr−1. We find a broad correlation between SFRUV and the bolometric quasar luminosity. Overall, our results show evidence for coeval star formation and black hole accretion occurring in luminous, reddened quasars at the peak epoch of galaxy formation.

Description

Keywords

galaxies: active, galaxies: evolution, galaxies: high-redshift, quasars: general, galaxies: star formation, ultraviolet: galaxies

Journal Title

Monthly Notices of the Royal Astronomical Society

Conference Name

Journal ISSN

0035-8711
1365-2966

Volume Title

475

Publisher

Oxford University Press (OUP)
Sponsorship
Science and Technology Facilities Council (ST/N000927/1)
Science and Technology Facilities Council (ST/M005305/1)
PPARC (via University College London (UCL)) (CJAAM)
Science and Technology Facilities Council (ST/K000985/1)
Science and Technology Facilities Council (ST/N002571/1)
STFC (1369580)
Science and Technology Facilities Council (1638336)