A fundamental problem in our understanding of low-mass galaxy evolution

By Simone M. Weinmann, A. Pasquali, B. Oppenheimer, K. Finlator, J. Trevor Mendel, Robert A. Crain, A. Macciò. 2012

139 citations recorded by the source corpus.

Recent studies have found a dramatic difference between the observed number density evolution of low-mass galaxies and that predicted by semi-analytic models. Whilst models accurately reproduce the z= 0 number density, they require that the evolution occurs rapidly at early times, which is incompatible with the strong late evolution found in observational results. We report here the same discrepancy in two state-of-the-art cosmological hydrodynamical simulations, which is evidence that the problem is fundamental. We search for the underlying cause of this problem using two complementary methods. First, we consider a narrow range in stellar mass of log (Mstar/(h−2M_)) = 9–9.5 and look for evidence of a different history of today’s low-mass galaxies in models and observations. We find that the exclusion of satellite galaxies from the analysis brings the median ages and star formation rates of galaxies into reasonable agreement. However, the models yield too few young, strongly star-forming galaxies. Secondly, we construct a toy model to link the observed evolution of specific star formation rates with the evolution of the galaxy stellar mass function. We infer from this model that a key problem in both semi-analytic and hydrodynamical models is the presence of a positive instead of a negative correlation between specific star formation rate and stellar mass. A similar positive correlation is found between the specific dark matter halo accretion rate and the halo mass, indicating that model galaxies are growing in a way that follows the growth of their host haloes too closely. It therefore appears necessary to find a mechanism that decouples the growth of low-mass galaxies, which occurs primarily at late times, from the growth of their host haloes, which occurs primarily at early times. We argue that the current form of star formation-driven feedback implemented in most galaxy formation models is unlikely to achieve this goal, owing to its fundamental dependence on host halo mass and time.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/af8bd4472dad13ea16cfd45ce7d64ede899e4bf7

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Citations in the corpus

A model for halo formation with axion mixed dark matter (2013, background): “Suppression of galaxy formation at high redshift has been invoked as a possible solution to another problem of structure formation in ΛCDM: the discrepancy in the evolution of the stellar mass function between observations and models, highlighted in Weinmann et al. (2012).”
THE AVERAGE STAR FORMATION HISTORIES OF GALAXIES IN DARK MATTER HALOS FROM z = 0–8 (2012, background): “So far, matching the evolution of the stellar masses and star formation rates of galaxies over this entire epoch with has proved difficult (see, e.g., Lu et al. 2012; Borgani & Kravtsov 2011; Weinmann et al. 2012).”
Galaxy formation in the Planck cosmology – I. Matching the observed evolution of star formation rates, colours and stellar masses (2014, background): “…and cosmological hydrodynamics simulations form low-mass galaxies too early, leading to an overabundance of lower mass galaxies (M⋆ ∼ 1010 M⊙) at z > 1 (Fontanot et al. 2009; Henriques et al. 2011; Guo et al. 2011; Weinmann et al. 2012; Lu et al. 2013; Genel et al. 2014; Vogelsberger et al. 2014).”
NIHAO project – I. Reproducing the inefficiency of galaxy formation across cosmic time with a large sample of cosmological hydrodynamical simulations (2015, background): “However, simultaneously reproducing the evolution has been a challenge (Weinmann et al. 2012; Hopkins et al. 2014).”
PRIMUS: CONSTRAINTS ON STAR FORMATION QUENCHING AND GALAXY MERGING, AND THE EVOLUTION OF THE STELLAR MASS FUNCTION FROM z = 0–1 (2013, background): “However, many discrepancies between observations and predictions persist (e.g., Fontana et al. 2006; Fontanot et al. 2009; Kereš et al. 2009; Davé et al. 2011a,b; Lu et al. 2012; Weinmann et al. 2012).”
Bent by baryons: the low-mass galaxy-halo relation (2014, background): “However, models that reproduce the abundance matching relation for low-mass galaxies often require very strong feedback, which can result in an unrealistically high passive fraction (Fontanot et al. 2009; Weinmann et al. 2012; Moster et al. 2013).”
The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations (2015, background): “…of galaxies from the growth of their parent halo, which is thought to be a necessary condition for reproducing the observed number density evolution of low-mass galaxies in a CDM cosmogony (e.g. Weinmann et al. 2012; Henriques et al. 2013; Mitchell et al. 2014; White, Somerville & Ferguson 2015).”
Star formation in semi-analytic galaxy formation models with multiphase gas (2015, background): “Weinmann et al. (2012) presented a similar study that showed that the same problems also occur in numerical hydrodynamic simulations, and recently Somerville & Davé (2014) showed that the problem persists to varying degrees in most state-of-the-art SAMs and cosmological hydrodynamical simulations.”
Physical Models of Galaxy Formation in a Cosmological Framework (2014, background): “This is an aspect of the “dwarf galaxy conundrum” highlighted in Weinmann et al. (2012) and White et al. (2014) and discussed above, which remains a puzzle: in current models that are normalized to fit the present-day SMF, dwarf galaxies not only form their stars too early (resulting in the…”
Deriving Physical Properties from Broadband Photometry with Prospector: Description of the Model and a Demonstration of its Accuracy Using 129 Galaxies in the Local Universe (2016, background): “This technique finds broad consistency at z 1< (Bell et al. 2007; Weinmann et al. 2012): however, at z 1 3= - , the observed SFRs and stellar masses are systematically incompatible with one another by a factor of ∼2 (Leja et al. 2015; Contini et al. 2016; Tomczak et al. 2016).”
REGULARITY UNDERLYING COMPLEXITY: A REDSHIFT-INDEPENDENT DESCRIPTION OF THE CONTINUOUS VARIATION OF GALAXY-SCALE MOLECULAR GAS PROPERTIES IN THE MASS-STAR FORMATION RATE PLANE (2013, unknown): “…2-SFM predictions might reflect the well-known problem that both semi-analytical models (e.g., Fontanot et al. 2009) and cosmological hydrodynamical simulations (e.g., Weinmann et al. 2012) tend to produce too many stars too early in the history of the universe, especially in lower mass galaxies.”
Evolution of galaxy stellar masses and star formation rates in the eagle simulations (2014, methodology): “Weinmann et al. (2012) and Genel et al. (2014) reported this issue for hydrodynamical simulations, while recent studies such as Mitchell et al. (2014) and White, Somerville & Ferguson (2015) revisited the issue with semi-analytic models.”
THE SFR–M* RELATION AND EMPIRICAL STAR FORMATION HISTORIES FROM ZFOURGE AT 0.5 < z < 4 (2015, background): “…our low-mass slope of γ ∼ 1 is consistent with the relative constancy of the lowmass slope α ∼ −1.5 of the SMF (Tomczak et al. 2014); if γ deviated significantly from unity then α would be expected to evolve strongly with redshift (Peng et al. 2010; Weinmann et al. 2012; Leja et al. 2015).”
Simulations of the galaxy population constrained by observations from z = 3 to the present day: implications for galactic winds and the fate of their ejecta (2012, methodology): “We note that the age discrepancy for the blue population between the G11-WMAP1/G11-WMAP7 model and the SDSS data appears larger here than in Weinmann et al. (2012) because that paper compared V-band weighted ages from the models with r-band weighted ages from SDSS.”
Radiative feedback and the low efficiency of galaxy formation in low-mass haloes at high redshift (2013, result): “As a result, the evolution in the number of galaxies at a fixed stellar mass is too fast at high redshifts,z > 2, and too slow at lower redshifts,z < 2, as compared to observations (Weinmann et al. 2012).”
The neutral hydrogen content of galaxies in cosmological hydrodynamic simulations (2013, background): “We note that SDSS observations do not indicate such a turnover (Salim et al. 2007), which reflects a generic problem in hierarchical models that star formation in dwarfs peaks too early and is too low today (Weinmann et al. 2012).”
Introducing the Illustris Project: simulating the coevolution of dark and visible matter in the Universe (2014, background): “We stress that this tension is shared by semi-analytic models and other state-of-the-art hydrodynamical simulations alike, pointing towards an open problem in low-mass galaxy formation (Weinmann et al. 2012; Henriques et al. 2013).”