J/AJ/143/133 Properties of dwarf galaxies from the ALFALFA survey (Huang+, 2012)
Gas, stars, and star formation in ALFALFA dwarf galaxies.
Huang S., Haynes M.P., Giovanelli R., Brinchmann J., Stierwalt S.,
Neff S.G.
<Astron. J., 143, 133 (2012)>
=2012AJ....143..133H 2012AJ....143..133H
ADC_Keywords: Galaxies, radio ; Photometry, ultraviolet ; Photometry, SDSS ;
H I data
Keywords: galaxies: dwarf - galaxies: evolution - galaxies: star formation -
galaxies: fundamental parameters - radio lines: galaxies; surveys
Abstract:
We examine the global properties of the stellar and HI components of
229 low HI mass dwarf galaxies extracted from the ALFALFA survey
(α.40; Haynes et al., 2011, Cat. J/AJ/142/170), including a
complete sample of 176 galaxies with HI masses<107.7M☉and HI
line widths<80km/s. Sloan Digital Sky Survey (SDSS; Cat . II/294
superseded by Cat. V/139) data are combined with photometric
properties derived from Galaxy Evolution Explorer (GALEX; GR5, Cat.
II/312) to derive stellar masses (M*) and star formation rates
(SFRs) by fitting their UV-optical spectral energy distributions
(SEDs). In optical images, many of the ALFALFA dwarfs are faint and of
low surface brightness; only 56% of those within the SDSS footprint
have a counterpart in the SDSS spectroscopic survey. A large fraction
of the dwarfs have high specific star formation rates (SSFRs), and
estimates of their SFRs and M* obtained by SED fitting are
systematically smaller than ones derived via standard formulae
assuming a constant SFR. The increased dispersion of the SSFR
distribution at M*≲108M☉ is driven by a set of dwarf
galaxies that have low gas fractions and SSFRs; some of these are
dE/dSphs in the Virgo Cluster. The imposition of an upper HI mass
limit yields the selection of a sample with lower gas fractions for
their M* than found for the overall ALFALFA population. Many of the
ALFALFA dwarfs, particularly the Virgo members, have HI depletion
timescales shorter than a Hubble time. An examination of the dwarf
galaxies within the full ALFALFA population in the context of global
star formation (SF) laws is consistent with the general assumptions
that gas-rich galaxies have lower SF efficiencies than do optically
selected populations and that HI disks are more extended than stellar
ones.
Description:
The α.40 catalog (Haynes et al., 2011, Cat. J/AJ/142/170) covers
40% (∼2800deg2) of the Arecibo Legacy Fast Arecibo L-band Feed Array
(ALFALFA) survey (begun in 2005) area in the regions 07h30m<RA<16h30m,
+04°<DEC<+16°, and +24°<DEC<+28° and 22h<RA<03h,
+14°<DEC<+16°, and +24°<DEC<+32°.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 119 229 Properties of ALFALFA dwarf sample
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
J/A+A/544/A65 : GALEX Arecibo SDSS survey. VI. (Catinella+, 2012)
J/A+A/527/A109 : Dust and PAH emission SEDs of disk galaxies (Popescu+, 2011)
J/ApJS/192/6 : A GALEX UV imaging survey of nearby galaxies (Lee+, 2011)
J/AJ/142/170 : ALFALFA survey: the a.40 HI source catalog (Haynes+, 2011)
J/AJ/139/315 : HI-selected galaxies in SDSS. Optical data (West+, 2010)
J/ApJ/706/599 : Hα and UV SFR in the local volume (Lee+, 2009)
J/AJ/138/338 : Arecibo legacy fast ALFA survey IX. (Stierwalt+, 2009)
J/ApJS/173/293 : UV-Optical galaxy color-magnitude diagram I. (Wyder+, 2007)
J/ApJS/173/185 : GALEX ultraviolet atlas of nearby galaxies (Gil de Paz+, 2007)
J/AJ/90/1681 : The Virgo Cluster Catalog (VCC) (Binggeli+, 1985)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- UGC/AGC ALFALFA catalog identifier (AGC number) (1)
7 A1 --- f_UGC/AGC [*] poor SED fitting (2)
9- 10 I2 h RAh Hour of Right Ascension (J2000) (3)
12- 13 I2 min RAm Minute of Right Ascension (J2000) (3)
15- 18 F4.1 s RAs Second of Right Ascension (J2000) (3)
20 A1 --- DE- Sign of the Declination (J2000) (3)
21- 22 I2 deg DEd Degree of Declination (J2000) (3)
24- 25 I2 arcmin DEm Arcminute of Declination (J2000) (3)
27- 28 I2 arcsec DEs Arcsecond of Declination (J2000) (3)
30 A1 --- f_FUV [d] Flag in FUV (d=non-detection)
31- 35 F5.2 mag FUV [13.66/22.09]? GALEX FUV band magnitude (4)
37- 40 F4.2 mag e_FUV ? Uncertainty in FUV (4)
42- 46 F5.2 mag NUV [13.44/22.04]? GALEX NUV band magnitude (4)
48- 51 F4.2 mag e_NUV ? Uncertainty in NUV (4)
53- 57 F5.2 mag rmag ? SDSS-DR7 pipeline r band modelmag
magnitude
59- 62 F4.2 mag e_rmag ? Uncertainty in rmag
64- 67 F4.2 mag u-r [0.3/3.78]? SDSS-DR7 pipeline (u-r)
color index
69- 72 F4.2 mag e_u-r ? Uncertainty in u-r
74- 79 A6 --- sFlag Flag in SDSS-DR7 photometry quality (5)
81- 84 F4.1 Mpc Dist [0.9/47.4] Adopted distance
86- 88 F3.1 Mpc e_Dist Uncertainty in Dist
90- 93 F4.2 [Msun] logMHI [6.11/9.04] Log of HI mass (6)
95- 98 F4.2 [Msun] e_logMHI Uncertainty in logMHI (6)
100-103 F4.2 [Msun] logM* [5.31/9.52]? Log of stellar mass, derived
from SED fitting (see Section 4.2)
105-108 F4.2 [Msun] e_logM* ? Uncertainty in logM*
110-114 F5.2 [Msun/yr] logSFR [-4.17/-0.92]? Log of the star formation
rate (see Section 4.5)
116-119 F4.2 [Msun/yr] e_logSFR ? Uncertainty in logSFR
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Note (1): Objects ≤12934 are .
Note (2):
* = the SED fitting of the galaxy has χ2best<10 (see Section 4.1).
Note (3): Of the optical counterpart assigned to the HI source.
Note (4): As derived via our reprocessing of the GALEX images (See Section 3.2).
Note (5): SDSS photometry quality as follows:
oly = ALFALFA dwarfs in the SDSS sample which are extracted as single
photometric objects by the SDSS pipeline (see Section 3.3).
par = Magnitudes of the associated parentID are adopted (see Section 3.3).
domi = We used the magnitudes of the brightest child (see Section 3.3).
pbphot = Photometry too uncertain to be used further, usually because the
parent object is blended with other sources or has no dominant child
(see Section 3.3).
Note (6): From the α.40 catalog (Haynes et al., 2011, Cat. J/AJ/142/170).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 04-Jul-2013