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Published August 21, 2018 | Submitted + Published
Journal Article Open

Halo histories versus galaxy properties at z = 0 – III. The properties of star-forming galaxies

Abstract

We measure how the properties of star-forming central galaxies correlate with large-scale environment, δ, measured on 10 h^(−1) Mpc scales. We use galaxy group catalogues to isolate a robust sample of central galaxies with high purity and completeness. The galaxy properties we investigate are star formation rate (SFR), exponential disc scale length R_(exp), and Sersic index of the galaxy light profile, n_S. We find that, at all stellar masses, there is an inverse correlation between SFR and δ, meaning that above-average star-forming centrals live in underdense regions. For n_S and R_(exp), there is no correlation with δ at M* ≲ 10^(10.5)M⊙, but at higher masses there are positive correlations; a weak correlation with R_(exp) and a strong correlation with n_S. These data are evidence of assembly bias within the star-forming population. The results for SFR are consistent with a model in which SFR correlates with present-day halo accretion rate, M_h. In this model, galaxies are assigned to haloes using the abundance-matching ansatz, which maps galaxy stellar mass onto halo mass. At fixed halo mass, SFR is then assigned to galaxies using the same approach, but M_h is used to map onto SFR. The best-fitting model requires some scatter in the M_h –SFR relation. The R_(exp) and n_S measurements are consistent with a model in which both of these quantities are correlated with the spin parameter of the halo, λ. Halo spin does not correlate with δ at low halo masses, but for higher mass haloes, high-spin haloes live in higher density environments at fixed M_h. Put together with the earlier instalments of this series, these data demonstrate that quenching processes have limited correlation with halo formation history, but the growth of active galaxies, as well as other detailed galaxies properties, are influenced by the details of halo assembly.

Additional Information

© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices). Accepted 2018 May 8. Received 2018 May 1; in original form 2017 May 24. Published: 18 May 2018. The authors wish to thank Michael Blanton, Rita Tojeiro, and Risa Wechsler for many useful discussions. The authors thank Matthew Becker for providing the Chinchilla simulation used in this work. The Chinchilla simulation and related analysis were performed using computational resources at SLAC. We thank the SLAC computational team for their consistent support. JLT acknowledges support from National Science Foundation grant AST-1615997. AW was supported by a Caltech-Carnegie Fellowship, in part through the Moore Center for Theoretical Cosmology and Physics at Caltech, and by NASA through grant HST-GO-14734 from STScI.

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August 19, 2023
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