The contribution of HI-bearing ultra-diffuse galaxies to the cosmic number density of galaxies

Abstract

We estimate the cosmic number density of the recently identified class of HI-bearing ultra-diffuse sources (HUDs) based on the completeness limits of the ALFALFA survey. These objects fall in the range $8.5<\log M_{\mathrm{HI}}/{\mathrm{M}}_{\odot }<9.5$, have average $r$-band surface brightnesses fainter than 24 mag arsec${}^{-2}$, half-light radii greater than 1.5 kpc, and are separated from neighbours by at least 350 kpc. We find that HUDs contribute at most 6% of the population of HI-bearing dwarfs, have a total cosmic number density of $(1.5\pm 0.6)\times 10^{-3}$ $\mathrm{Mp}{\mathrm{c}}^{-3}$, and an HI mass density of $(6.0\pm 0.8)\times 10^5$ ${\mathrm{M}}_{\odot }\mathrm{Mp}{\mathrm{c}}^{-3}$. We estimate that this is similar to the total cosmic number density of UDGs in groups and clusters, and conclude that the relation between the number of UDGs hosted in a halo and the halo mass, must have a break below $M_{200}\sim 10^{12}$ ${\mathrm{M}}_{\odot }$ in order to account for the abundance of HUDs. The distribution of the velocity widths of HUDs rises steeply towards low values, indicating a preference for slow rotation rates. These objects have been absent from measurements of the galaxy stellar mass function owing to their low surface brightness. However, we estimate that due to their low number density, their inclusion would constitute a correction of less than 1%. Comparison with the Santa Cruz SAM shows that it produces HI-rich central UDGs that have similar colours to HUDs, but these are currently produced in much great a number. While previous results from this sample have favoured formation scenarios where HUDs form in high spin parameter halos, comparisons with the results of Rong et al. 2017, which invokes that formation mechanism, reveal that this model produces an order of magnitude more field UDGs than we observe in the HUD population.(Abridged)

Accepted for publication in A&A, 11 pages, 5 figures, 1 table

References in corpus (15)

• A Semi-Analytic Model for the Co-evolution of Galaxies, Black Holes, and Active Galactic Nuclei
• Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma Cluster
• NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows
• Is there a "too big to fail" problem in the field?
• Extensive Globular Cluster Systems Associated with Ultra Diffuse Galaxies in the Coma Cluster
• Galaxy And Mass Assembly (GAMA): The galaxy stellar mass function to $z=0.1$ from the r-band selected equatorial regions
• The abundance of ultra-diffuse galaxies from groups to clusters: UDGs are relatively more common in more massive haloes
• Understanding the Structural Scaling Relations of Early-Type Galaxies
• The nearest ultra diffuse galaxy: UGC2162
• When the Jeans don't fit: How stellar feedback drives stellar kinematics and complicates dynamical modeling in low-mass galaxies
• Empirical distributions of galactic $\lambda$ spin parameters from the SDSS
• Constraining the HI-Halo Mass Relation From Galaxy Clustering
• Atomic Gas in Blue Ultra Diffuse Galaxies around Hickson Compact Groups
• The Relationship Between Star-formation Activity and Galaxy Structural Properties in CANDELS and a Semi-analytic Model
• KDG 218, a Nearby Ultra-Diffuse Galaxy

Cited by in corpus (25)

• The Formation of Ultra Diffuse Galaxies in Cored Dark Matter Halos Through Tidal Stripping and Heating
• Gravitational probes of dark matter physics
• Off the baryonic Tully-Fisher relation: a population of baryon-dominated ultra-diffuse galaxies
• Robust HI kinematics of gas-rich ultra-diffuse galaxies: hints of a weak-feedback formation scenario
• The Formation of Isolated Ultra-Diffuse Galaxies in Romulus25
• Observational Properties of Ultra-Diffuse Galaxies in the Field: Field-UDGs are Predominantly Blue and Starforming
• The evolution of ultra-diffuse galaxies in nearby galaxy clusters from the Kapteyn IAC WEAVE INT Clusters Survey ($\text{KIWICS}$)
• Discovery of a red ultra-diffuse galaxy in a nearby void based on its globular cluster luminosity function
• Implications for Galaxy Formation Models from Observations of Globular Clusters around Ultra-Diffuse Galaxies
• Origin and evolution of ultra-diffuse galaxies in different environments
• The globular clusters and star formation history of the isolated, quiescent ultra-diffuse galaxy DGSAT I
• The emergence of dark matter-deficient ultra-diffuse galaxies driven by scatter in the stellar mass-halo mass relation and feedback from globular clusters
• The environment of HI-bearing ultra diffuse galaxies in the ALFALFA survey
• Gas-rich, field ultra-diffuse galaxies host few globular clusters
• Edge-on HI-bearing ultra diffuse galaxy candidates in the 40% ALFALFA catalog
• The halo mass function of late-type galaxies from HI kinematics
• 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
• The Nature of Low Surface Brightness Galaxies in the Hyper Suprime-Cam Survey
• Photometry and kinematics of dwarf galaxies from the Apertif HI survey
• Ultra-Diffuse Galaxies (UDGs) with Hyper Suprime-Cam I: Revised Catalog of Coma Cluster UDGs
• No need for dark matter: resolved kinematics of the ultra-diffuse galaxy AGC 114905
• The stellar mass - physical effective radius relation for dwarf galaxies in low-density environments
• Dark-Matter-Deficient Galaxies from Collisions: A New Probe of Bursty Feedback and Dark Matter Physics
• VLA Imaging of HI-bearing Ultra-Diffuse Galaxies from the ALFALFA Survey
• Evidence for Ultra-Diffuse Galaxy Formation Through Tidal Heating of Normal Dwarfs