The nature of CR7 revealed with MUSE:A young starburst powering extended Lyman-α emission at z=6.6

Matthee, Jorryt and Pezzulli, Gabriele and Mackenzie, Ruari and Cantalupo, Sebastiano and Kusakabe, Haruka and Leclercq, Floriane and Sobral, David and Richard, Johan and Wisotzki, Lutz and Lilly, Simon and Boogaard, Leindert and Marino, Raffaella and Maseda, Michael and Nanayakkara, Themiya (2020) The nature of CR7 revealed with MUSE:A young starburst powering extended Lyman-α emission at z=6.6. Monthly Notices of the Royal Astronomical Society. ISSN 0035-8711

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Abstract

CR7 is among the most luminous Lyman-α emitters (LAEs) known at z = 6.6 and consists of at least three UV components that are surrounded by Lyman-α (Lyα) emission. Previous studies have suggested that it may host an extreme ionising source. Here, we present deep integral field spectroscopy of CR7 with VLT/MUSE. We measure extended emission with a similar halo scale length as typical LAEs at z ≈ 5. CR7’s Lyα halo is clearly elongated along the direction connecting the multiple components, likely tracing the underlying gas distribution. The Lyα emission originates almost exclusively from the brightest UV component, but we also identify a faint kinematically distinct Lyα emitting region nearby a fainter component. Combined with new near-infrared data, the MUSE data show that the rest-frame Lyα equivalent width (EW) is ≈100 Å. This is a factor four higher than the EW measured in low-redshift analogues with carefully matched Lyα profiles (and thus arguably HI column density), but this EW can plausibly be explained by star formation. Alternative scenarios requiring AGN powering are also disfavoured by the narrower and steeper Lyα spectrum and much smaller IR to UV ratio compared to obscured AGN in other Lyα blobs. CR7’s Lyα emission, while extremely luminous, resembles the emission in more common LAEs at lower redshifts very well and is likely powered by a young metal poor starburst.

Item Type:
Journal Article
Journal or Publication Title:
Monthly Notices of the Royal Astronomical Society
Additional Information:
This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version Jorryt Matthee, Gabriele Pezzulli, Ruari Mackenzie, Sebastiano Cantalupo, Haruka Kusakabe, Floriane Leclercq, David Sobral, Johan Richard, Lutz Wisotzki, Simon Lilly, Leindert Boogaard, Raffaella Marino, Michael Maseda, Themiya Nanayakkara, The nature of CR7 revealed with MUSE: a young starburst powering extended Lyman-α emission at z=6.6, Monthly Notices of the Royal Astronomical Society, ?? , staa2550 is available online at: ???
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1900/1912
Subjects:
ID Code:
146744
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Deposited On:
24 Aug 2020 10:45
Refereed?:
Yes
Published?:
Published
Last Modified:
22 Sep 2020 05:10