A Flexible Analytic Model of Cosmic Variance in the First Billion Years

Abstract

Cosmic variance is the intrinsic scatter in the number density of galaxies due to fluctuations in the large-scale dark matter density field. In this work, we present a simple analytic model of cosmic variance in the high redshift Universe ($z\sim 5-15$). We assume that galaxies grow according to the evolution of the halo mass function, which we allow to vary with large-scale environment. Our model produces a reasonable match to the observed ultraviolet luminosity functions in this era by regulating star formation through stellar feedback and assuming that the UV luminosity function is dominated by recent star formation. We find that cosmic variance in the UVLF is dominated by the variance in the underlying dark matter halo population, and not by differences in halo accretion or the specifics of our stellar feedback model. We also find that cosmic variance dominates over Poisson noise for future high-$z$ surveys except for the brightest sources or at very high redshifts ($z\gtrsim 12$). We provide a linear approximation of cosmic variance for a variety of redshifts, magnitudes, and survey areas through the public Python package galcv. Finally, we introduce a new method for incorporating priors on cosmic variance into estimates of the galaxy luminosity function and demonstrate that it significantly improves constraints on that important observable.

16 pages, 15 figures, accepted by MNRAS

References in corpus (15)

• The NumPy array: a structure for efficient numerical computation
• Cosmic Star Formation History
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Wide-Field InfrarRed Survey Telescope-Astrophysics Focused Telescope Assets WFIRST-AFTA 2015 Report
• Assembly bias in the clustering of dark matter haloes
• The high redshift galaxy population in hierarchical galaxy formation models
• A lack of evolution in the very bright-end of the galaxy luminosity function from z = 8-10
• The Wide Field Infrared Survey Telescope: 100 Hubbles for the 2020s
• The Global 21-cm Signal in the Context of the High-z Galaxy Luminosity Function
• Coming of Age in the Dark Sector: How Dark Matter Haloes grow their Gravitational Potential Wells
• An Empirically-Calibrated Model For Interpreting the Evolution of Galaxies During the Reionization Era
• Accounting for Cosmic Variance in Studies of Gravitationally-Lensed High-Redshift Galaxies in the Hubble Frontier Field Clusters
• Effects of self-consistent rest-ultraviolet colours in semi-empirical galaxy formation models
• Testing the conditional mass function of dark matter halos against numerical N-body simulations
• A prescription for the conditional mass function of dark matter haloes

Cited by in corpus (20)

• COSMOS2020: The Galaxy Stellar Mass Function: the assembly and star formation cessation of galaxies at $0.2<z\le 7.5$
• Life beyond 30: probing the -20<M_UV<-17 luminosity function at 8<z<13 with the NIRCam parallel field of the MIRI Deep Survey
• Balancing the efficiency and stochasticity of star formation with dust extinction in z > 10 galaxies observed by JWST
• Probing Cosmic Reionization and Molecular Gas Growth with TIME
• The Prevalence of Galaxy Overdensities Around UV-Luminous Lyman $\alpha$ Emitters in the Epoch of Reionization
• GALLUMI: A Galaxy Luminosity Function Pipeline for Cosmology and Astrophysics
• Constraints on the End of Reionization from the Density Fields Surrounding Two Highly Opaque Quasar Sightlines
• Deep Realistic Extragalactic Model (DREaM) Galaxy Catalogs: Predictions for a Roman Ultra-Deep Field
• JWST UNCOVER: The Overabundance of Ultraviolet-luminous Galaxies at $z>9$
• On the Significance of Rare Objects at High Redshift: The Impact of Cosmic Variance
• The importance of stochasticity in determining galaxy emissivities and UV LFs during cosmic dawn and reionization
• Lyman-alpha Emitters in Ionized Bubbles: Constraining the Environment and Ionized Fraction
• The first GLIMPSE of the faint galaxy population at Cosmic Dawn with JWST: The evolution of the ultraviolet luminosity function across z~9-15
• The impact of medium-width bands on the selection, and subsequent luminosity function measurements, of high-z galaxies
• Efficient simulation of discrete galaxy populations and associated radiation fields during the first billion years
• A Framework for Simultaneously Measuring Field Densities and the High-z Luminosity Function
• First Light and Reionisation Epoch Simulations (FLARES) X: Environmental Galaxy Bias and Survey Variance at High Redshift
• An X-ray-Emitting Proto-Cluster at $z\approx 5.7$ Reveals Rapid Structure Growth
• Finding High-Redshift Galaxies with JWST
• A joint measurement of galaxy luminosity functions and large-scale field densities during the Epoch of Reionization