Clues to the nature of dark matter from first galaxies

Abstract

We use thirty-eight high-resolution simulations of galaxy formation between redshift 10 and 5 to study the impact of a 3 keV warm dark matter (WDM) candidate on the high-redshift Universe. We focus our attention on the stellar mass function and the global star formation rate and consider the consequences for reionization, namely the neutral hydrogen fraction evolution and the electron scattering optical depth. We find that three different effects contribute to differentiate warm and cold dark matter (CDM) predictions: WDM suppresses the number of haloes with mass less than few $10^9$ M${}_{\odot }$; at a fixed halo mass, WDM produces fewer stars than CDM; and finally at halo masses below $10^9$ M${}_{\odot }$, WDM has a larger fraction of dark haloes than CDM post-reionization. These three effects combine to produce a lower stellar mass function in WDM for galaxies with stellar masses at and below $\sim 10^7$ M${}_{\odot }$. For $z>7$, the global star formation density is lower by a factor of two in the WDM scenario, and for a fixed escape fraction, the fraction of neutral hydrogen is higher by 0.3 at $z\sim 6$. This latter quantity can be partially reconciled with CDM and observations only by increasing the escape fraction from 23 per cent to 34 per cent. Overall, our study shows that galaxy formation simulations at high redshift are a key tool to differentiate between dark matter candidates given a model for baryonic physics.

11 pages, 8 figures, submitted to MNRAS

References in corpus (18)

• Astrophysics Source Code Library
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Model-independent evidence in favor of an end to reionization by z~6
• The First Billion Years Project: The escape fraction of ionizing photons in the epoch of reionization
• Dark Matter Evidence, Particle Physics Candidates and Detection Methods
• On the Structure of Dark Matter Halos at the Damping Scale of the Power Spectrum with and without Relict Velocities
• Lighting the Universe with filaments
• The phase space density of fermionic dark matter haloes
• NIHAO X: Reconciling the local galaxy velocity function with Cold Dark Matter via mock HI observations
• The Efficiency of Stellar Reionization: Effects of Rotation, Metallicity, and Initial Mass Function
• Early galaxy formation in warm dark matter cosmologies
• The Lyman Continuum escape fraction of emission line-selected $z\sim 2.5$ galaxies is less than 15%
• Probing the Neutral Fraction of the IGM with GRBs during the Epoch of Reionization
• The edge of galaxy formation I: formation and evolution of MW-satellites analogues before accretion
• The edge of galaxy formation II: evolution of Milky Way satellite analogues after infall
• Warm Dark Matter and Cosmic Reionization
• The edge of galaxy formation III: The effects of warm dark matter on Milky Way satellites and field dwarfs
• Constraining warm dark matter mass with cosmic reionization and gravitational wave