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Colours, star formation rates and environments of star-forming and quiescent galaxies at the cosmic noon


Feldmann, Robert; Quataert, Eliot; Hopkins, Philip F; Faucher-Giguère, Claude-André; Kereš, Dušan (2017). Colours, star formation rates and environments of star-forming and quiescent galaxies at the cosmic noon. Monthly Notices of the Royal Astronomical Society, 470(1):1050-1072.

Abstract

We analyse the star formation rates (SFRs), colours and dust extinctions of galaxies in massive (1012.5 − 1013.5M⊙) haloes at z ∼ 2 in high-resolution, cosmological zoom-in simulations as part of the Feedback In Realistic Environments (FIRE) project. The simulations do not model feedback from active galactic nuclei (AGNs) but reproduce well the observed relations between stellar and halo mass and between stellar mass and SFR. About half (a third) of the simulated massive galaxies (massive central galaxies) at z ∼ 2 have broad-band colours classifying them as ‘quiescent’, and the fraction of quiescent centrals is steeply decreasing towards higher redshift, in agreement with observations. The progenitors of z ∼ 2 quiescent central galaxies are, on average, more massive, have lower specific SFRs and reside in more massive haloes than the progenitors of similarly massive star-forming centrals. The simulations further predict a morphological mix of galaxies that includes disc-dominated, irregular and early-type galaxies. However, our simulations do not reproduce the reddest of the quiescent galaxies observed at z ∼ 2. We also do not find evidence for a colour bimodality, but are limited by our modest sample size. In our simulations, the star formation activity of central galaxies of moderate mass (Mstar ∼ 1010 − 1011M⊙) is affected by a combination of two distinct physical processes. Outflows powered by stellar feedback result in a short-lived (<100 Myr), but almost complete, suppression of star formation activity after which many galaxies quickly recover and continue to form stars at normal rates. In addition, galaxies residing in slowly growing haloes tend to experience a moderate reduction of their SFRs (‘cosmological starvation’). The relative importance of these processes and AGN feedback is uncertain and will be explored in future work.

Abstract

We analyse the star formation rates (SFRs), colours and dust extinctions of galaxies in massive (1012.5 − 1013.5M⊙) haloes at z ∼ 2 in high-resolution, cosmological zoom-in simulations as part of the Feedback In Realistic Environments (FIRE) project. The simulations do not model feedback from active galactic nuclei (AGNs) but reproduce well the observed relations between stellar and halo mass and between stellar mass and SFR. About half (a third) of the simulated massive galaxies (massive central galaxies) at z ∼ 2 have broad-band colours classifying them as ‘quiescent’, and the fraction of quiescent centrals is steeply decreasing towards higher redshift, in agreement with observations. The progenitors of z ∼ 2 quiescent central galaxies are, on average, more massive, have lower specific SFRs and reside in more massive haloes than the progenitors of similarly massive star-forming centrals. The simulations further predict a morphological mix of galaxies that includes disc-dominated, irregular and early-type galaxies. However, our simulations do not reproduce the reddest of the quiescent galaxies observed at z ∼ 2. We also do not find evidence for a colour bimodality, but are limited by our modest sample size. In our simulations, the star formation activity of central galaxies of moderate mass (Mstar ∼ 1010 − 1011M⊙) is affected by a combination of two distinct physical processes. Outflows powered by stellar feedback result in a short-lived (<100 Myr), but almost complete, suppression of star formation activity after which many galaxies quickly recover and continue to form stars at normal rates. In addition, galaxies residing in slowly growing haloes tend to experience a moderate reduction of their SFRs (‘cosmological starvation’). The relative importance of these processes and AGN feedback is uncertain and will be explored in future work.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Date:May 2017
Deposited On:09 Jan 2018 20:39
Last Modified:19 Aug 2018 12:09
Publisher:Oxford University Press
ISSN:0035-8711
Additional Information: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 Royal Astronomical Society. All rights reserved.
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1093/mnras/stx1120
Project Information:
  • : FunderSNSF
  • : Grant IDPP00P2_157591
  • : Project TitleAiming for the Parsec Scale - Star Formation and Feedback Processes in High Redshift Galaxies

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