TY - JOUR
T1 - MUFASA
T2 - The strength and evolution of galaxy conformity in various tracers
AU - Rafieferantsoa, Mika
AU - Davé, Romeel
N1 - Funding Information:
The authors thank G. Kauffmann for providing us with the observational data and useful ideas for this work, and helpful suggestions from the referee. The authors also thank F. Durier and T. Naab for helpful conversations and guidance. MR and RD acknowledge support from the South African Research Chairs Initiative and the South African National Research Foundation. MR acknowledges financial support from Max-Planck-Institüt für Astrophysik. Support for MR was also provided by the Square Kilometre Array post-graduate bursary program. The MUFASA simulations were run on the Pumbaa astrophysics computing cluster hosted at the University of the Western Cape, which was generously funded by UWC’s Office of the Deputy Vice Chancellor. Additional computing resources are obtained from the Max Planck Computing and Data Facility (http://www.mpcdf.mpg.de).
Publisher Copyright:
© 2017 The Author(s).
PY - 2018/3/21
Y1 - 2018/3/21
N2 - We investigate galaxy conformity using the MUFASA cosmological hydrodynamical simulation. We show a bimodal distribution in galaxy colour with radius, albeit with too many lowmass quenched satellite galaxies compared to observations. MUFASA produces conformity in observed properties such as colour, specific star formation rate (sSFR), and HI content, i.e. neighbouring galaxies have similar properties. We see analogous trends in other properties such as in environment, stellar age, H2 content, and metallicity. We introduce quantifying conformity using S(R), measuring the relative difference in upper and lower quartile properties of the neighbours. We show that low-mass and non-quenched haloes have weak conformity (S(R) ≲ 0.5) extending to large projected radii R in all properties, while high-mass and quenched haloes have strong conformity (S(R) ~ 1) that diminishes rapidly with R and disappears at R ≳ 1Mpc. S(R) is strongest for environment in low-mass haloes, and sSFR (or colour) in high-mass haloes, and is dominated by one-halo conformity with the exception of HI in small haloes. Metallicity shows a curious anticonformity in massive haloes. Tracking the evolution of conformity for z = 0 galaxies back in time shows that conformity broadly emerges as a late-time (z ≲ 1) phenomenon. However, for fixed halo mass bins, conformity is fairly constant with redshift out to z ≳ 2. These trends are consistent with the idea that strong conformity only emerges once haloes grow above MUFASA's quenching mass scale of ~1012Mo˙. A quantitative measure of conformity in various properties, along with its evolution, thus represents a new and stringent test of the impact of quenching on environment within current galaxy formation models.
AB - We investigate galaxy conformity using the MUFASA cosmological hydrodynamical simulation. We show a bimodal distribution in galaxy colour with radius, albeit with too many lowmass quenched satellite galaxies compared to observations. MUFASA produces conformity in observed properties such as colour, specific star formation rate (sSFR), and HI content, i.e. neighbouring galaxies have similar properties. We see analogous trends in other properties such as in environment, stellar age, H2 content, and metallicity. We introduce quantifying conformity using S(R), measuring the relative difference in upper and lower quartile properties of the neighbours. We show that low-mass and non-quenched haloes have weak conformity (S(R) ≲ 0.5) extending to large projected radii R in all properties, while high-mass and quenched haloes have strong conformity (S(R) ~ 1) that diminishes rapidly with R and disappears at R ≳ 1Mpc. S(R) is strongest for environment in low-mass haloes, and sSFR (or colour) in high-mass haloes, and is dominated by one-halo conformity with the exception of HI in small haloes. Metallicity shows a curious anticonformity in massive haloes. Tracking the evolution of conformity for z = 0 galaxies back in time shows that conformity broadly emerges as a late-time (z ≲ 1) phenomenon. However, for fixed halo mass bins, conformity is fairly constant with redshift out to z ≳ 2. These trends are consistent with the idea that strong conformity only emerges once haloes grow above MUFASA's quenching mass scale of ~1012Mo˙. A quantitative measure of conformity in various properties, along with its evolution, thus represents a new and stringent test of the impact of quenching on environment within current galaxy formation models.
KW - Galaxies: Evolution
KW - Galaxies: Formation
KW - Galaxies: Statistics
KW - Methods: Numerical
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U2 - 10.1093/mnras/stx3293
DO - 10.1093/mnras/stx3293
M3 - Article
AN - SCOPUS:85041324286
SN - 0035-8711
VL - 475
SP - 955
EP - 973
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
M1 - stx3293
ER -