Bent by baryons: the low-mass galaxy-halo relation

By T. Sawala, Carlos S. Frenk, Azadeh Fattahi, J. Navarro, Richard G. Bower, Robert A. Crain, Claudio Dalla Vecchia, Michelle Furlong, Adrian Jenkins, Ian G. McCarthy and 9 more. 2014

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The relation between galaxies and dark matter halos is of vital importance for evaluating theoretical predictions of structure formation and galaxy formation physics. We show that the widely used method of abundance matching based on dark matter only simulations fails at the low mass end because two of its underlying assumptions are broken: only a small fraction of low mass (< 109:5M�) halos host a visible galaxy, and halos grow at a lower rate due to the effect of baryons. In this regime, reliance on dark matter only simulations for abundance matching is neither accurate nor self-consistent. We find that the reported discrepancy between observational estimates of the halo masses of dwarf galaxies and the values predicted by abundance matching does not point to a failure of �CDM, but simply to a failure to account for baryonic effects. Our results also imply that the Local Group contains only a few hundred observable galaxies in contrast with the thousands of faint dwarfs that abundance matching would suggest. We show how relations derived from abundance matching can be corrected, so that they can be used self-consistently to calibrate models of galaxy formation. Key words: cosmology: theory, galaxies: formation, galaxies: evolution, galaxies: mass functions, methods: N-body simulations

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/4ecfd548433cf9eb8764428b50320ec27f5a84b6

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Citations in the corpus

Not so lumpy after all: modelling the depletion of dark matter subhaloes by Milky Way-like galaxies (2017, background): “…in this field (e.g. di Cintio et al. 2011; Governato et al. 2012; Pontzen & Governato 2012; Zolotov et al. 2012; Brooks & Zolotov 2014; Arraki et al. 2014; Sawala et al. 2015; Di Cintio et al. 2014; Oñorbe et al. 2015; Chan et al. 2015; Sawala et al. 2016b; Cui et al. 2016; Wetzel et al. 2016).”
The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time (2016, methodology): “…to follow the hydrodynamics: e.g. adaptive mesh refinement codes (e.g. Teyssier 2002; Bryan et al. 2014); smoothed particle hydrodynamics (SPH) codes (used in, e.g. Scannapieco et al. 2008; Guedes et al. 2011; Stinson et al. 2013b; Sawala et al. 2015) and moving mesh codes (Marinacci et al. 2014a).”
The APOSTLE project: Local Group kinematic mass constraints and simulation candidate selection (2015, methodology): “…(which we shall hereafter refer to as APOSTLE, a shorthand for ‘A Project Of Simulating The Local Environment’), which uses the same code developed for the EAGLE simulations (Crain et al. 2015; Schaye et al. 2015), have already been reported in Sawala et al. (2015, 2016) and Oman et al. (2015).”
Cosmic Dawn (CoDa): the first radiation-hydrodynamics simulation of reionization and galaxy formation in the Local Universe (2015, unknown): “Thanks to this simplification in the treat- ment of the EoR, they were able to carry out their simulation down to z=0 and show that such a mass-dependent reduction in the fraction of luminous haloes is able to quantitatively match the observed abundance of satellites (Sawala et al. 2015).”
Sweating the small stuff: simulating dwarf galaxies, ultra-faint dwarf galaxies, and their own tiny satellites (2015, methodology): “…we are unable to determine whether the apparent break and associated stochasticity in our relation at small mass are physical or simply artifacts of resolution, although it is intriguing that the break witnessed by Sawala et al. (2015) occurs at the mass of ∼ 10 of their baryonic particles as well.”
Forged in FIRE: cusps, cores and baryons in low-mass dwarf galaxies (2015, result): “Recent work by Sawala et al. (2015, 2014), however, suggests that the scale at which stochasticity becomes important is somewhat lower (Mvir ∼ 109 − 109.5M ).”
The masses and density profiles of halos in a LCDM galaxy formation simulation (2014, background): “These models of supernova and AGN feedback are extensions of the models developed for the Virgo Consortium projects OWLS (Schaye et al. 2010) and GIMIC (Crain et al. 2009).”
EMERGE – an empirical model for the formation of galaxies since z ∼ 10 (2017, background): “First, reionisation suppresses galaxy formation in haloes that have a low mass early-on (Efstathiou 1992), which can lead to dark subhaloes that do not host a galaxy (Sawala et al. 2015).”
The unexpected diversity of dwarf galaxy rotation curves (2015, methodology): “2 C I R C U L A R V E L O C I T Y P RO F I L E S O F S I M U L AT E D G A L A X I E S We discuss here the circular velocity curves of galaxies selected from the EAGLE (Crain et al. 2015; Schaye et al. 2015) and LG (Sawala et al. 2015) simulation projects.”
Small scale problems of the $\Lambda$CDM model: a short review (2016, background): “s the Local Group, and Local Volume galaxies [296,297,386], which galaxies are too massive to be modiﬁed by (reionisation) feedback [35,70,283,293,387–389], contrary to the baryonic solution of Refs. [57,71,72,390]. Nevertheless, such limitation of feedback were challenged for a few galaxies by [134”
The upper bound on the lowest mass halo (2016, background): “On the other hand, Sawala et al. (2015) predict that the SMHM becomes shallower at low masses.”