The Evolution of Galaxy Number Density at z < 8 and its Implications

Abstract

The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However there has never been a detailed study of this important measurement, nor a clear path to answer it. To address this we use observed galaxy stellar mass functions up to $z\sim 8$ to determine how the number densities of galaxies changes as a function of time and mass limit. We show that the increase in the total number density of galaxies (${\varphi }_{\mathrm{T}}$), more massive than M${}_{\ast }=10^6$ M_0, decreases as ${\varphi }_{\mathrm{T}}\sim t^{-1}$, where $t$ is the age of the universe. We further show that this evolution turns-over and rather increases with time at higher mass lower limits of M${}_{\ast }>10^7$ M_0. By using the M${}_{\ast }=10^6$ M_0 lower limit we further show that the total number of galaxies in the universe up to $z=8$ is $2.0_{-0.6}^{+0.7}\times 10^{12}$ (two trillion), almost a factor of ten higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth. We discuss the implications for these results for galaxy evolution, as well as compare our results with the latest models of galaxy formation. These results also reveal that the cosmic background light in the optical and near-infrared likely arise from these unobserved faint galaxies. We also show how these results solve the question of why the sky at night is dark, otherwise known as Olbers' paradox.

Accepted to AAS journals (ApJ), 22 pages, matches final published version

References in corpus (25)

• Cosmic Star Formation History
• Properties of galaxies reproduced by a hydrodynamic simulation
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Introducing the Illustris Project: the evolution of galaxy populations across cosmic time
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• The Hubble Ultra Deep Field
• A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy
• The Evolution of Galaxy Structure over Cosmic Time
• Galaxies in the Hubble Ultra Deep Field: I. Detection, Multiband Photometry, Photometric Redshifts, and Morphology
• The Galaxy Mass Function up to z=4 in the GOODS-MUSIC sample: into the epoch of formation of massive galaxies
• The galaxy stellar mass function at 3.5<z<7.5 in the CANDELS/UDS, GOODS-South, and HUDF fields
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• z~7-10 Galaxies in the HUDF and GOODS fields, and their UV Luminosity Functions
• The Redshift Evolution of Wet, Dry, and Mixed Galaxy Mergers from Close Galaxy Pairs in the DEEP2 Galaxy Redshift Survey
• The Structures of Distant Galaxies I: Galaxy Structures and the Merger Rate to z~3 in the Hubble Ultra-Deep Field
• The luminosity function, halo masses and stellar masses of luminous Lyman-break galaxies at redshifts 5<z<6
• AEGIS: Enhancement of Dust-enshrouded Star Formation in Close Galaxy Pairs and Merging Galaxies up to z ~ 1
• MOIRCS Deep Survey IV: Evolution of Galaxy Stellar Mass Function Back to z ~ 3
• Deconstructing the Galaxy Stellar Mass Function with UKIDSS and CANDELS: the Impact of Colour, Structure and Environment
• Exploring the evolutionary paths of the most massive galaxies since z~2
• Minor vs Major Mergers: The Stellar Mass Growth of Massive Galaxies from z=3 using Number Density Selection Techniques
• Keck spectroscopy of the faint dwarf elliptical galaxy population in the Perseus Cluster core: mixed stellar populations and a flat luminosity function
• Frontier Fields : Combining HST, VLT and Spitzer data to explore the $z$$\sim$8 Universe behind the lensing cluster MACS0416$-$2403
• Low-mass galaxy formation and the ionizing photon budget during reionization
• The Role of Bulge Formation in the Homogenization of Stellar Populations at $z\sim 2$ as revealed by Internal Color Dispersion in CANDELS

Cited by in corpus (64)

• Active Galactic Nuclei: what's in a name?
• Galaxy Formation and Reionization: Key Unknowns and Expected Breakthroughs by the James Webb Space Telescope
• JWST's PEARLS: Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results
• An observational determination of the evolving extragalactic background light from the multiwavelength HST/CANDELS survey in the Fermi and CTA era
• The Cosmic Evolution of Binary Black Holes in Young, Globular and Nuclear Star Clusters: Rates, Masses, Spins and Mixing Fractions
• The Science of the Einstein Telescope
• Anomalous Flux in the Cosmic Optical Background Detected With New Horizons Observations
• New Horizons Observations of the Cosmic Optical Background
• Implications for the Supermassive Black Hole Binaries from the NANOGrav 15-year Data Set
• GA-NIFS: The core of an extremely massive proto-cluster at the Epoch of Reionization probed with JWST/NIRSpec
• Primordial Black Holes from Confinement
• A direct measurement of galaxy major and minor merger rates and stellar mass accretion histories at $z<3$ using galaxy pairs in the REFINE survey
• Massive Black Holes from Dissipative Dark Matter
• Constraining the era of helium reionization using fast radio bursts
• The cosmic optical background excess, dark matter, and line-intensity mapping
• A panchromatic spatially-resolved analysis of nearby galaxies -- I. Sub-kpc scale Main Sequence in grand-design spirals
• A Measurement of the Cosmic Optical Background and Diffuse Galactic Light Scaling from the R < 50 AU New Horizons-LORRI Data
• [CII] line intensity mapping the epoch of reionization with the Prime-Cam on FYST
• GW190521 from the Merger of Ultra-Dwarf Galaxies
• Galaxy classification: a deep learning approach for classifying Sloan Digital Sky Survey images
• Milky Way as a Neutrino Desert Revealed by IceCube Galactic Plane Observation
• Source anisotropies and pulsar timing arrays
• The gravitational capture of compact objects by massive black holes
• Surface Brightness Evolution of Galaxies in the CANDELS GOODS Fields up to $z\sim 6$: High-z Galaxies are Unique or Remain Undetected
• The Tully-Fisher relation in dense groups at $z\sim 0.7$ in the MAGIC survey
• SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-Sky Surface-Brightness Measurements: II. First Limits on Diffuse Light at 1.25, 1.4, and 1.6 microns
• Constraints on UHECR sources and extragalactic magnetic fields from directional anisotropies
• If Loud Aliens Explain Human Earliness, Quiet Aliens Are Also Rare
• The clustering of dark sirens' invisible host galaxies
• Gravitational waves from merging intermediate-mass black holes : II Event rates at ground-based detectors
• SKYSURF-4: Panchromatic HST All-Sky Surface-Brightness Measurement Methods and Results
• On the Tidal Capture of White Dwarfs by Intermediate-mass Black Holes in Dense Stellar Environments
• Less Wound and More Asymmetric: JWST Confirms the Evolution of Spiral Structure in Galaxies at $z\lesssim 3$
• Emission Line Galaxies in the SHARDS Frontier Fields I: Candidate Selection and the Discovery of Bursty Hα Emitters
• Strategies for Maximizing Detection Rate in Radio SETI
• Stellar mass Primordial Black Holes as Cold Dark Matter
• Reconciling the 16.35-day period of FRB 20180916B with jet precession
• Pupil Masks for Spectrophotometry of Transiting Exoplanets
• Constraints on galaxy formation from the cosmic-far-infrared-background\,$-$\,optical-imaging cross-correlation using \textit{Herschel} and UNIONS
• The formation of compact massive relic galaxies in MOND
• Gravitational Wave Sources from Pop III Stars are Preferentially Located within the Cores of their Host Galaxies
• DeepGalaxy: Deducing the Properties of Galaxy Mergers from Images Using Deep Neural Networks
• Statistical properties of fast radio bursts elucidate their origins: magnetars are favoured over gamma-ray bursts
• The large-scale anisotropy and flux (de-)magnification of ultra-high-energy cosmic rays in the Galactic magnetic field
• Supernova-Neutrino-Boosted Dark Matter from All Galaxies
• A FRB in a Globular Cluster: Why Is This Neutron Star Different From (Almost) All Other Neutron Stars?
• Dancing with invisible partners: Three-body exchanges with primordial black holes
• Mass Distribution of Binary Black Hole Mergers from Young and Old Dense Star Clusters
• MOCCA-Survey Database: Extra Galactic Globular Clusters. III. The population of black holes in Milky Way and Andromeda-like galaxies
• Emission Line Galaxies in the SHARDS Hubble Frontier Fields II: Limits on Lyman-Continuum Escape Fractions of Lensed Emission Line Galaxies at Redshifts 2 < z < 3.5
• Bright siren without electromagnetic counterpart by LISA-Taiji-TianQin network
• Interrelations between Astrochemistry and Galactic Dynamics
• ZTF SN Ia DR2: Impact of the galaxy cluster environment on the stretch distribution of Type Ia supernovae
• Resonant Locking Between Binary Systems Induced by Gravitational Waves
• Faint Galaxy Number Counts in the Durhamand SDSS Catalogues
• SKYSURF-11: A New Zodiacal Light Model Optimized for Optical Wavelengths
• Gamma-ray emission from primordial black hole-neutron star interaction
• Impact of the cosmological expansion on spectral energy density of radiation in the intergalactic medium and once more about Olbers' paradox
• Introducing the FLAMINGOS-2 Split-K Medium Band Filters: The Impact on Photometric Selection of High-z Galaxies in the FENIKS-pilot survey
• X-raying the galaxy pair Arp 41: no collision in NGC 1232 and three ultraluminous sources in NGC 1232A
• Percolation of 'Civilisation' in a Homogeneous Isotropic Universe
• Lagrangian Perturbation Theory for Biased Tracers: Significance of the Number Conservation
• Modelling the host galaxies of binary compact object mergers with observational scaling relations
• Calculation of Dark Matter as a Feature of Space-Time