Is the dark-matter halo spin a predictor of galaxy spin and size?
[1];
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[8];
- Center for Astrophysics and Planetary Science, Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
- Center for Astrophysics and Planetary Science, Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel, SCIPP, University of California, Santa Cruz, CA 95064, USA
- Institut für Theoretische Astrophysik, Zentrum für Astronomie, Universität Heidelberg, Albert-Ueberle-Str 2, D-69120 Heidelberg, Germany
- Department of Physics, University of California, Santa Cruz, CA 95064, USA
- Department of Astronomy, University of California, Santa Cruz, CA 95064, USA
- New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates, Max Planck Institute für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
- New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates
- Center for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USA, Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA
- Center for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USA, Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Rd, Piscataway, NJ 08854, USA
The similarity between the distributions of spins for galaxies (λgal) and for dark-matter haloes (λhalo), indicated both by simulations and observations, is naively interpreted as a one-to-one correlation between the spins of a galaxy and its host halo. This is used to predict galaxy sizes in semi-analytic models via Re ≃ fjλhaloRvir, where Re is the half-mass radius of the galaxy, fj is the angular momentum retention factor, and Rvir is the halo radius. Using two suites of zoom-in cosmological simulations, we find that λgal and the λhalo of its host halo are in fact barely correlated, especially at z ≥ 1, in line with previous indications. Since the spins of baryons and dark matter are correlated at accretion into Rvir, the null correlation in the end reflects an anticorrelation between fj and λhalo, which can arise from mergers and a ‘wet compaction’ phase that many high-redshift galaxies undergo. It may also reflect that unrepresentative small fractions of baryons are tapped to the galaxies. The galaxy spin is better correlated with the spin of the inner halo, but this largely reflects the effect of the baryons on the halo. While λhalo is not a useful predictor for Re, our simulations reproduce a general relation of the form of Re = ARvir, in agreement with observational estimates. Finally, we find that the relation becomes tighter with A = 0.02(c/10)-0.7, where c is the halo concentration, which in turn introduces a dependence on mass and redshift.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Aeronautics and Space Administration (NASA)
- Grant/Contract Number:
- ISF 124/12; PBC/ISF 1829/12; BSF 2014-273; PICS 2015-18; NSF AST-1405962; HST-AR-14578.001-A
- OSTI ID:
- 1564358
- Alternate ID(s):
- OSTI ID: 1577798
- Journal Information:
- Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Vol. 488 Journal Issue: 4; ISSN 0035-8711
- Publisher:
- Royal Astronomical SocietyCopyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English
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