Abstract
We present a sample of 115 very low optical surface brightness, highly extended, H I-rich galaxies carefully selected from the ALFALFA survey that have similar optical absolute magnitudes, surface brightnesses, and radii to recently discovered "ultra-diffuse" galaxies (UDGs). However, these systems are bluer and have more irregular morphologies than other UDGs, are isolated, and contain significant reservoirs of H I. We find that while these sources have normal star formation rates for H I-selected galaxies of similar stellar mass, they have very low star formation efficiencies. We further present deep optical and H I-synthesis follow-up imaging of three of these H I-bearing ultra-diffuse sources. We measure H I diameters extending to similar to 40 kpc, but note that while all three sources have large H I diameters for their stellar mass, they are consistent with the H I mass-H I radius relation. We further analyze the H I velocity widths and rotation velocities for the unresolved and resolved sources, respectively, and find that the sources appear to inhabit halos of dwarf galaxies. We estimate spin parameters, and suggest that these sources may exist in high spin parameter halos, and as such may be potential H I-rich progenitors to the ultra-diffuse galaxies observed in cluster environments.
| Original language | English |
|---|---|
| Article number | 133 |
| Number of pages | 17 |
| Journal | The Astrophysical Journal |
| Volume | 842 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 20 Jun 2017 |
Cite this
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(Almost) Dark Galaxies in the ALFALFA Survey : Isolated HI-bearing Ultra-diffuse Galaxies. / Leisman, Lukas; Haynes, Martha P.; Janowiecki, Steven; Hallenbeck, Gregory; Jozsa, Gyula; Giovanelli, Riccardo; Adams, Elizabeth A. K.; Neira, David Bernal; Cannon, John M.; Janesh, William F.; Rhode, Katherine L.; Salzer, John J.
In: The Astrophysical Journal, Vol. 842, No. 2, 133, 20.06.2017.Research output: Contribution to journal › Article
TY - JOUR
T1 - (Almost) Dark Galaxies in the ALFALFA Survey
T2 - Isolated HI-bearing Ultra-diffuse Galaxies
AU - Leisman, Lukas
AU - Haynes, Martha P.
AU - Janowiecki, Steven
AU - Hallenbeck, Gregory
AU - Jozsa, Gyula
AU - Giovanelli, Riccardo
AU - Adams, Elizabeth A. K.
AU - Neira, David Bernal
AU - Cannon, John M.
AU - Janesh, William F.
AU - Rhode, Katherine L.
AU - Salzer, John J.
PY - 2017/6/20
Y1 - 2017/6/20
N2 - We present a sample of 115 very low optical surface brightness, highly extended, H I-rich galaxies carefully selected from the ALFALFA survey that have similar optical absolute magnitudes, surface brightnesses, and radii to recently discovered "ultra-diffuse" galaxies (UDGs). However, these systems are bluer and have more irregular morphologies than other UDGs, are isolated, and contain significant reservoirs of H I. We find that while these sources have normal star formation rates for H I-selected galaxies of similar stellar mass, they have very low star formation efficiencies. We further present deep optical and H I-synthesis follow-up imaging of three of these H I-bearing ultra-diffuse sources. We measure H I diameters extending to similar to 40 kpc, but note that while all three sources have large H I diameters for their stellar mass, they are consistent with the H I mass-H I radius relation. We further analyze the H I velocity widths and rotation velocities for the unresolved and resolved sources, respectively, and find that the sources appear to inhabit halos of dwarf galaxies. We estimate spin parameters, and suggest that these sources may exist in high spin parameter halos, and as such may be potential H I-rich progenitors to the ultra-diffuse galaxies observed in cluster environments.
AB - We present a sample of 115 very low optical surface brightness, highly extended, H I-rich galaxies carefully selected from the ALFALFA survey that have similar optical absolute magnitudes, surface brightnesses, and radii to recently discovered "ultra-diffuse" galaxies (UDGs). However, these systems are bluer and have more irregular morphologies than other UDGs, are isolated, and contain significant reservoirs of H I. We find that while these sources have normal star formation rates for H I-selected galaxies of similar stellar mass, they have very low star formation efficiencies. We further present deep optical and H I-synthesis follow-up imaging of three of these H I-bearing ultra-diffuse sources. We measure H I diameters extending to similar to 40 kpc, but note that while all three sources have large H I diameters for their stellar mass, they are consistent with the H I mass-H I radius relation. We further analyze the H I velocity widths and rotation velocities for the unresolved and resolved sources, respectively, and find that the sources appear to inhabit halos of dwarf galaxies. We estimate spin parameters, and suggest that these sources may exist in high spin parameter halos, and as such may be potential H I-rich progenitors to the ultra-diffuse galaxies observed in cluster environments.
KW - galaxies: evolution
KW - galaxies: star formation
KW - radio lines: galaxies
KW - SURFACE BRIGHTNESS GALAXIES
KW - DIGITAL SKY SURVEY
KW - FAST ALPHA SURVEY
KW - STAR-FORMATION EFFICIENCY
KW - I-RICH GALAXIES
KW - IRREGULAR GALAXIES
KW - NEARBY GALAXIES
KW - VIRGO CLUSTER
KW - COMA CLUSTER
KW - MILKY-WAY
U2 - 10.3847/1538-4357/aa7575
DO - 10.3847/1538-4357/aa7575
M3 - Article
VL - 842
JO - The Astrophysical Journal
JF - The Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 133
ER -