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Witnessing galaxy assembly in an extended z~3 structure

Fumagalli, M.; Mackenzie, R.; Trayford, J.; Theuns, T.; Cantalupo, S.; Christensen, L.; Fynbo, J.P.U.; Moller, P.; O'Meara, J.; Prochaska, J.X; Rafelski, M.; Shanks, T.

Witnessing galaxy assembly in an extended z~3 structure Thumbnail


Authors

R. Mackenzie

J. Trayford

S. Cantalupo

L. Christensen

J.P.U. Fynbo

P. Moller

J. O'Meara

J.X Prochaska

M. Rafelski

T. Shanks



Abstract

We present new observations acquired with the Multi Unit Spectroscopic Explorer instrument on the Very Large Telescope in a quasar field that hosts a high column density damped Lyα absorber (DLA) at z ≈ 3.25. We detect Lyα emission from a nebula at the redshift of the DLA with line luminosity (27 ± 1) × 1041 erg s− 1, which extends over 37 ± 1 kpc above a surface brightness limit of 6 × 10−19 erg s− 1 cm− 2 arcsec− 2 at a projected distance of 30.5 ± 0.5 kpc from the quasar sightline. Two clumps lie inside this nebula, both with Lyα rest-frame equivalent width > 50 Å and with relative line-of-sight velocities aligned with two main absorption components seen in the DLA spectrum. In addition, we identify a compact galaxy at a projected distance of 19.1 ± 0.5 kpc from the quasar sightline. The galaxy spectrum is noisy but consistent with that of a star-forming galaxy at the DLA redshift. We argue that the Lyα nebula is ionized by radiation from star formation inside the two clumps, or by radiation from the compact galaxy. In either case, these data imply the presence of a structure with size ≫50 kpc inside which galaxies are assembling, a picture consistent with galaxy formation in groups and filaments as predicted by cosmological simulations such as the EAGLE simulations.

Citation

Fumagalli, M., Mackenzie, R., Trayford, J., Theuns, T., Cantalupo, S., Christensen, L., …Shanks, T. (2017). Witnessing galaxy assembly in an extended z~3 structure. Monthly Notices of the Royal Astronomical Society, 471(3), 3686-3698. https://doi.org/10.1093/mnras/stx1896

Journal Article Type Article
Acceptance Date Jul 19, 2017
Online Publication Date Jul 26, 2017
Publication Date Jan 1, 2017
Deposit Date Jul 25, 2017
Publicly Available Date Mar 28, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 471
Issue 3
Pages 3686-3698
DOI https://doi.org/10.1093/mnras/stx1896
Related Public URLs https://arxiv.org/abs/1707.07003

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2017. The Authors.
Published by Oxford University Press on behalf of the Royal Astronomical Society.






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