J/ApJ/842/133 HI-bearing ultra-diffuse ALFALFA galaxies (Leisman+, 2017)
(Almost) dark galaxies in the ALFALFA survey: isolated H I-bearing
ultra-diffuse galaxies.
Leisman L., Haynes M.P., Janowiecki S., Hallenbeck G., Jozsa G.,
Giovanelli R., Adams E.A.K., Neira D.B., Cannon J.M., Janesh W.F.,
Rhode K.L., Salzer J.J.
<Astrophys. J., 842, 133 (2017)>
=2017ApJ...842..133L 2017ApJ...842..133L
ADC_Keywords: Galaxies, optical ; H I data ; Magnitudes, absolute ; Extinction ;
Galaxies, photometry ; Morphology
Keywords: galaxies: evolution; galaxies: star formation; radio lines: galaxies
Abstract:
We present a sample of 115 very low optical surface brightness, highly
extended, HI-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
HI. We find that while these sources have normal star formation rates
for HI-selected galaxies of similar stellar mass, they have very low
star formation efficiencies. We further present deep optical and
HI-synthesis follow-up imaging of three of these HI-bearing
ultra-diffuse sources. We measure HI diameters extending to ∼40kpc,
but note that while all three sources have large HI diameters for
their stellar mass, they are consistent with the HI mass-HI radius
relation. We further analyze the HI 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 HI-rich
progenitors to the ultra-diffuse galaxies observed in cluster
environments.
Description:
All sources discussed here have available SDSS and ALFALFA data. The
ALFALFA observations, data reduction, and catalog products are
detailed elsewhere (e.g., Giovanelli+ 2005AJ....130.2598G 2005AJ....130.2598G ; Saintonge
2007AJ....133.2087S 2007AJ....133.2087S ; Haynes+ 2011, J/AJ/142/170).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 111 115 Properties of HI-bearing ultra-diffuse ALFALFA
sources (HUDS)
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See also:
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
J/ApJS/105/209 : Low surface brightness galaxies. I. (Impey+ 1996)
J/A+A/324/877 : HI properties of spiral & irregular gal. (Broeils+, 1997)
J/ApJS/162/49 : UBV imaging of irregular galaxies (Hunter+, 2006)
J/AJ/133/2569 : Arecibo legacy fast ALFA survey III. (Giovanelli+, 2007)
J/AJ/135/588 : Arecibo legacy fast ALFA survey V. (Saintonge+, 2008)
J/AJ/136/713 : Arecibo legacy fast ALFA survey. VI. (Kent+, 2008)
J/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)
J/AJ/136/2563 : HI Nearby Galaxy Survey, THINGS (Walter+, 2008)
J/ApJS/183/214 : Arecibo Legacy Fast ALFA Survey. VIII. (Martin+, 2009)
J/AJ/138/338 : Arecibo Legacy Fast ALFA Survey. IX. (Stierwalt+, 2009)
J/AJ/142/170 : ALFALFA survey: α.40 HI source catalog (Haynes+, 2011)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/MNRAS/460/2143 : HI size-mass relation of galaxies (Wang+, 2016)
J/ApJS/225/11 : Subaru-UDGs in the Coma cluster (Yagi+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- AGC [102791/749488] Arecibo General Catalog ID
8- 15 F8.4 deg RAdeg Right Ascension (J2000)
17- 23 F7.4 deg DEdeg Declination (J2000)
25- 28 I4 km/s cz [1796/8416] Recessional velocity
30- 32 I3 km/s W50 [19/215] Width of the HI line measured at
the 50% flux level, corrected for channel
broadening
34- 35 I2 km/s e_W50 [2/59] W50 error
37- 40 F4.2 Jy.km/s SdV [0.3/3.5] HI line flux density
42- 45 F4.2 Jy.km/s e_SdV [0.02/0.1] Flux density error
47- 49 I3 Mpc Dist [28/120] Distance from ALFALFA
flow model (1)
51- 54 F4.2 [Msun] logMHI [7.9/9.5] HI mass
56- 59 F4.2 [Msun] e_logMHI [0.05/0.2] HI mass error (1)
61- 65 F5.2 mag/arcsec2 mug0 [23/25.4] g-band central surface
brightness (2)
67- 70 F4.2 mag/arcsec2 e_mug0 [0.1/0.4] g-band central SB error
72- 74 F3.1 kpc rh [1.6/8] Half light radius
76- 78 F3.1 kpc e_rh [0.2/3.3] Half light radius error (1)
80- 84 F5.1 mag gMAG [-17.1/-13.9] g-band absolute magnitude (3)
86- 88 F3.1 mag e_gMAG [0.3/1.1] gMAG error (1)
90- 94 F5.2 mag g-r [-0.2/0.9] g minus r color index (2)
96- 99 F4.2 mag e_g-r [0.1/2] g-r color error
101-104 F4.2 mag Ag [0.05/0.8] g band galactic extinction (4)
106-109 F4.2 mag Ar [0.03/0.6] r band galactic extinction (4)
111-111 A1 --- Set Broad (B) or Restrictive (R) Sample
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Note (1): Distance dependent quantity errors include an assumed distance
error of 350km/s or 5Mpc.
Note (2): Not corrected for galactic dust extinction
Note (3): g-band absolute magnitudes are calculated from total integrated
magnitudes from the surface brightness profile using the ALFALFA flow
model distance. These total magnitudes are not truncated, and are
significantly brighter than aperture magnitudes.
USE WITH CAUTION.
Note (4): Galactic dust extinction corrections are derived from the
Schlafly & Finkbeiner (2011ApJ...737..103S 2011ApJ...737..103S) recalibration of the
Schlegel et al. (1998ApJ...500..525S 1998ApJ...500..525S) COBE and IRAS dust maps, and
assume Rv=3.1. They are included simply as a convenience to the
reader.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 02-Feb-2018