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The formation of massive, compact galaxies at z = 2 in the Illustris simulation

Wellons, Sarah and Torrey, Paul and Ma, Chung-Pei and Rodriguez-Gomez, Vicente and Vogelsberger, Mark and Kriek, Mariska and van Dokkum, Pieter and Nelson, Erica and Genel, Shy and Pillepich, Annalisa and Springel, Volker and Sijacki, Debora and Snyder, Gregory and Nelson, Dylan and Sales, Laura and Hernquist, Lars (2015) The formation of massive, compact galaxies at z = 2 in the Illustris simulation. Monthly Notices of the Royal Astronomical Society, 449 (1). pp. 361-372. ISSN 0035-8711.

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Massive, quiescent galaxies at high redshift have been found to be considerably more compact than galaxies of similar mass in the local universe. How these compact galaxies formed has yet to be determined, though several progenitor populations have been proposed. Here we investigate the formation processes and quantify the assembly histories of such galaxies in Illustris, a suite of hydrodynamical cosmological simulations encompassing a sufficiently large volume to include rare objects, while simultaneously resolving the internal structure of galaxies. We select massive (∼10^(11) M_⊙) and compact (stellar half-mass radius <2 kpc) galaxies from the simulation at z = 2. Within the Illustris suite, we find that these quantities are not perfectly converged, but are reasonably reliable for our purposes. The resulting population is composed primarily of quiescent galaxies, but we also find several star-forming compact galaxies. The simulated compact galaxies are similar to observed galaxies in star formation activity and appearance. We follow their evolution at high redshift in the simulation and find that there are multiple pathways to form these compact galaxies, dominated by two mechanisms: (i) intense, centrally concentrated starbursts generally triggered by gas-rich major mergers between z ∼ 2–4, reducing the galaxies’ half-mass radii by a factor of a few to below 2 kpc, and (ii) assembly at very early times when the universe was much denser; the galaxies formed compact and remained so until z ∼ 2.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Torrey, Paul0000-0002-5653-0786
Rodriguez-Gomez, Vicente0000-0002-9495-0079
Vogelsberger, Mark0000-0001-8593-7692
Kriek, Mariska0000-0002-7613-9872
van Dokkum, Pieter0000-0002-8282-9888
Nelson, Erica0000-0002-7524-374X
Genel, Shy0000-0002-3185-1540
Pillepich, Annalisa0000-0003-1065-9274
Springel, Volker0000-0001-5976-4599
Hernquist, Lars0000-0001-6950-1629
Additional Information:© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 February 11. Received 2015 January 20; in original form 2014 October 31. First published online March 17, 2015. SW is supported by the National Science Foundation Graduate Research Fellowship under grant number DGE1144152. LH acknowledges support from NASA grant NNX12AC67G and NSF grant AST-1312095. We thank Pascal Oesch for helpful discussions and guidance on generating the mock observations presented in this paper.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144152
Subject Keywords:galaxies: formation galaxies: high-redshift
Issue or Number:1
Record Number:CaltechAUTHORS:20150629-071627195
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Official Citation:Sarah Wellons, Paul Torrey, Chung-Pei Ma, Vicente Rodriguez-Gomez, Mark Vogelsberger, Mariska Kriek, Pieter van Dokkum, Erica Nelson, Shy Genel, Annalisa Pillepich, Volker Springel, Debora Sijacki, Gregory Snyder, Dylan Nelson, Laura Sales, and Lars Hernquist The formation of massive, compact galaxies at z = 2 in the Illustris simulation MNRAS (May 1, 2015) Vol. 449 361-372 doi:10.1093/mnras/stv303 First published online March 17, 2015
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58648
Deposited By: Ruth Sustaita
Deposited On:29 Jun 2015 15:07
Last Modified:09 Mar 2020 13:19

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