Reversal of Fortune: Increased Star Formation Efficiencies in the Early Histories of Dwarf Galaxies?

Abstract

On dwarf galaxy scales, the different shapes of the galaxy stellar mass function and the dark halo mass function require a star-formation efficiency (SFE) in these systems that is currently more than 1 dex lower than that of Milky Way-size halos. Here, we argue that this trend may actually be reversed at high redshift. Specifically, by combining the resolved star-formation histories of nearby isolated dwarfs with the simulated mass-growth rates of dark matter halos, we show that the assembly of these systems occurs in two phases: (1) an early, fast halo accretion phase with a rapidly deepening potential well, characterized by a high SFE; and (2) a late slow halo accretion phase where, perhaps as a consequence of reionization, the SFE is low. Nearby dwarfs have more old stars than predicted by assuming a constant or decreasing SFE with redshift, a behavior that appears to deviate qualitatively from the trends seen amongst more massive systems. Taken at face value, the data suggest that, at sufficiently early epochs, dwarf galaxy halos above the atomic cooling mass limit can be among the most efficient sites of star formation in the universe.

arXiv comment6 pages, 5 figures, accepted for publication in the Astrophysical Journal Letters

References in corpus (41)

• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• Dark Matter Substructure in Galactic Halos
• Where are the missing galactic satellites?
• The Average Star Formation Histories of Galaxies in Dark Matter Halos from z=0-8
• At the heart of the matter: the origin of bulgeless dwarf galaxies and Dark Matter cores
• Halos and galaxies in the standard cosmological model: results from the Bolshoi simulation
• Clumps and streams in the local dark matter distribution
• Reionization and the abundance of galactic satellites
• The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies
• Effect of Reionization on the Structure Formation in the Universe
• Gasoline: An adaptable implementation of TreeSPH
• The Merger Rates and Mass Assembly Histories of Dark Matter Haloes in the Two Millennium Simulations
• The tumultuous lives of galactic dwarfs and the missing satellites problem
• Formation and evolution of galaxy dark matter halos and their substructure
• The ACS Nearby Galaxy Survey Treasury
• New Constraints on Cosmic Reionization from the 2012 Hubble Ultra Deep Field Campaign
• Massloss of galaxies due to a UV-background
• The Star Formation Histories of Local Group Dwarf Galaxies I. Hubble Space Telescope / Wide Field Planetary Camera 2 Observations
• Hydrodynamic Simulations of Galaxy Formation. II. Photoionization and the Formation of Low Mass Galaxies
• Stellar Feedback in Dwarf Galaxy Formation
• The ACS Nearby Galaxy Survey Treasury VIII. The Global Star Formation Histories of 60 Dwarf Galaxies in the Local Volume
• Cold dark matter heats up
• Photoionization Feedback in Low--Mass Galaxies at High Redshift
• Lower-Luminosity Galaxies could reionize the Universe: Very Steep Faint-End Slopes to the UV Luminosity Functions at z>=5-8 from the HUDF09 WFC3/IR Observations
• A quantitative explanation of the observed population of Milky Way satellite galaxies
• Early Metal Enrichment by Pregalactic Outflows: II. Simulations of Blow-away
• The pseudo-evolution of halo mass
• Leo A: A Late-Blooming Survivor of the Epoch of Reionization in the Local Group
• On the Last 10 Billion Years of Stellar Mass Growth in Star-Forming Galaxies
• The ACS LCID project. V. The Star Formation History of the Dwarf Galaxy \objectname[]{LGS-3}: Clues for Cosmic Reionization and Feedback
• Dark Matter Heating and Early Core Formation in Dwarf Galaxies
• On the Kennicutt-Schmidt relation of low-metallicity high-redshift galaxies
• What is the (Dark) Matter with Dwarf Galaxies?
• On the extended structure of the Phoenix dwarf galaxy
• The ACS LCID project. X. The Star Formation History of IC 1613: Revisiting the Over-Cooling Problem
• The ACS LCID project. IX. Imprints of the early Universe in the radial variation of the star formation history of dwarf galaxies
• Formation of Sub-galactic Clouds under UV Background Radiation
• An Empirical Model for the Star Formation History in Dark Matter Halos
• Fossil remnants of reionization in the halo of the Milky Way
• On the assembly of the Milky Way dwarf satellites and their common mass scale
• Dwarf Galaxy Formation with H2-Regulated Star Formation: II. Gas-Rich Dark Galaxies at Redshift 2.5

Cited by in corpus (17)

• A redshift-independent efficiency model: star formation and stellar masses in dark matter halos at z>4
• Faint dwarfs as a test of DM models: WDM vs. CDM
• The Local Group as a time machine: studying the high-redshift Universe with nearby galaxies
• Low-mass galaxy assembly in simulations: regulation of early star formation by radiation from massive stars
• Local Group Ultra-Faint Dwarf Galaxies in the Reionization Era
• Star Formation and Stellar Mass Assembly in Dark Matter Halos: From Giants to Dwarfs
• Scaling relations and baryonic cycling in local star-forming galaxies: II. Gas content and star-formation efficiency
• The Dark Energy Survey 5-year photometrically identified Type Ia Supernovae
• On the Physical Requirements for a Pre-Reionization Origin of the Unresolved Near-Infrared Background
• Star Cluster Formation and Survival in the First Galaxies
• UniverseMachine: Predicting Galaxy Star Formation over Seven Decades of Halo Mass with Zoom-in Simulations
• Scaling relations and baryonic cycling in local star-forming galaxies. III. Outflows, effective yields and metal loading factors
• The evolution of dwarf galaxy satellites with different dark matter density profiles in the ErisMod simulations. I. The early infalls
• Push it to the limit: Local Group constraints on high-redshift stellar mass functions for Mstar > 10^5 Msun
• Constraining the nature of dark matter with the star formation history of the faintest Local Group dwarf galaxy satellites
• The THESAN-ZOOM project: Star-formation efficiencies in high-redshift galaxies
• A Model For Intergalactic Filaments and Galaxy Formation During the First Gigayear