J/MNRAS/403/683 GALEX Arecibo SDSS survey (GASS) (Catinella+, 2010)
The GALEX Arecibo SDSS survey.
I. Gas fraction scaling relations of massive galaxies and first data release.
Catinella B., Schiminovich D., Kauffmann G., Fabello S., Wang J.,
Hummels C., Lemonias J., Moran S.M., Wu R., Giovanelli R., Haynes M.P.,
Heckman T.M., Basu-Zych A.R., Blanton M.R., Brinchmann J., Budavari T.,
Goncalves T., Johnson B.D., Kennicutt R.C., Madore B.F., Martin C.D.,
Rich M.R., Tacconi L.J., Thilker D.A., Wild V., Wyder T.K.
<Mon. Not. R. Astron. Soc., 403, 683-708 (2010)>
=2010MNRAS.403..683C 2010MNRAS.403..683C
ADC_Keywords: Galaxy catalogs ; Ultraviolet ; H I data
Keywords: galaxies: evolution - galaxies: fundamental parameters -
radio lines: galaxies - ultraviolet: galaxies
Abstract:
We introduce the GALEX Arecibo SDSS Survey (GASS), an on-going large
programme that is gathering high quality HI-line spectra using the
Arecibo radio telescope for an unbiased sample of ∼1000 galaxies
with stellar masses greater than 1010M☉ and redshifts
0.025<z<0.05, selected from the Sloan Digital Sky Survey (SDSS)
spectroscopic and Galaxy Evolution Explorer (GALEX) imaging surveys.
The galaxies are observed until detected or until a low gas mass
fraction limit (1.5-5 per cent) is reached. This paper presents the
first Data Release, consisting of ∼20 per cent of the final GASS
sample. We use this data set to explore the main scaling relations of
the HI gas fraction with galaxy structure and NUV-r colour.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 86 176 Relevant SDSS and UV quantities for the GASS
objects published in this work
table2.dat 93 99 HI properties of GASS detections
table3.dat 55 77 GASS non-detection
appen.dat 80 183 Individual notes
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See also:
II/294 : SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/AJ/130/825 : GALEX ultraviolet variability catalog (Welsh+, 2005)
J/AJ/136/259 : Second GALEX UV variability catalog (GUVV-2) (Wheatley+, 2008)
J/ApJ/688/290 : GASS HI survey of the lower halo (Ford+, 2008)
J/ApJS/183/214 : Arecibo Legacy Fast Alfa Survey (ALFALFA) VIII (Martin+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- GASS GASS identification number
7- 25 A19 --- SDSS SDSS designation (JHHMMSS.ss+DDMMSS.s)
27- 32 F6.4 --- z SDSS redshift (1)
34- 38 F5.2 [Msun] logM Stellar mass (2)
40- 43 F4.2 arcsec R50.z Radii containing 50% of the Petrosian flux
in the z band
45- 49 F5.2 arcsec R50.r Radii containing 50% of the Petrosian flux
in the r band
51- 55 F5.2 arcsec R90.r Radii containing 90% of the Petrosian flux
in the r band
57- 60 F4.2 [Msun/kpc2] logmu Stellar mass surface density (3)
62- 65 F4.2 mag Ar Galactic extinction in the r band, from SDSS
67- 71 F5.2 mag rmag r-band model magnitude from the SDSS,
corrected for Galactic extinction
73- 76 F4.2 mag NUV-r ?=- NUV-r observed colour from our reprocessed
photometry, corrected for Galactic extinction
78- 82 I5 s TNUV ?=- Exposure time of the GALEX NUV image
84- 86 I3 min Tmax Maximum on-source integration time, required
to reach the limiting HI mass fraction (4)
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Note (1): The typical uncertainty of SDSS redshifts for this sample is 0.0002.
Note (2): Stellar masses are derived from SDSS photometry using the
methodology described in Salim et al. (2007ApJS..173..267S 2007ApJS..173..267S; a Chabrier
(2003PASP..115..763C 2003PASP..115..763C) initial mass function is assumed). Over our required
stellar mass range, these values are believed to be accurate to better than
30 per cent, significantly smaller than the uncertainty on other derived
physical parameters such as SFRs. This accuracy in M* is more than
sufficient for this study.
Note (3): This quantity is defined as mu=Mass/(2πR50,z2), with R50,z
in kpc units.
Note (4): see Section 2. Given the HI mass limit of the galaxy (set by its gas
fraction limit and stellar mass), we computed the required integration time
to reach this limit at the galaxy's redshift, assuming a 5σ signal
with 300km/s velocity width and the instrumental parameters typical of our
observations (i.e. gain of ∼10K/Jy and system temperature of ∼28K at 1370MHz).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- GASS GASS identification number
7- 25 A19 --- SDSS SDSS designation (JHHMMSS.ss+DDMMSS.s)
27- 32 F6.4 --- z SDSS redshift (1)
34- 35 I2 min Ton On-source integration time of the Arecibo
observation (1)
37- 38 I2 km/s DV Velocity resolution of the final,
smoothed spectrum
40- 47 F8.6 --- zHI Redshift, measured from the Hi spectrum (2)
49- 51 I3 km/s W50 Observed velocity width of the source line
profile, measured at 50% level of each peak
53- 54 I2 km/s e_W50 Error on the width (sum in quadrature of the
statistical and systematic uncertainties) (3)
56- 58 I3 km/s W50c Velocity width corrected for instrumental
broadening and cosmological redshift only (4)
60- 63 F4.2 Jy.km/s FHI Observed, integrated HI-line flux density,
F=∫Sdv, measured on the smoothed and
baseline-subtracted spectrum
65- 68 F4.2 Jy.km/s e_FHI Uncertainty on FHI (sum in quadrature of the
statistical and systematic errors) (5)
70- 73 F4.2 mJy rms rms noise of the observation, measured on the
signal- and RFI-free portion of the smoothed
spectrum
75- 78 F4.1 --- S/N Signal-to-noise ratio of the HI spectrum (6)
80- 84 F5.2 [Msun] logMHI base-10 logarithm of the HI mass (7)
86- 90 F5.2 --- logMHI/M* base-10 logarithm of the HI mass fraction
92 I1 --- Q [1/5] Quality flag
(1=good, 2=marginal, 5=confused) (8)
93 A1 --- Note [*] An asterisk indicates the presence of a
note for the source in appen.dat file
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Note (1): This number refers to on-scans that were actually combined and does
not account for possible losses due to RFI excision (usually negligible).
Note (2): The error on the corresponding heliocentric velocity, cz, is half the
error on the width, tabulated in column W50.
Note (3): Statistical errors depend primarily on the S/N of the HI spectrum and
are obtained from the rms noise of the linear fits to the edges of the HI
profile. Systematic errors depend on the subjective choice of the HI signal
boundaries and are estimated as explained in Giovanelli et al. (2007, Cat.
J/AJ/133/2569). These are negligible for most of the galaxies in this sample
(only 17 objects have systematic errors greater than zero).
Note (4): No inclination or turbulent motion corrections are applied.
Note (5): The statistical errors are calculated according to equation (2) of
Springob et al. (2005, Cat. VIII/77).
Note (6): estimated following Saintonge (2007AJ....133.2087S 2007AJ....133.2087S) and adapted to the
velocity resolution of the spectrum. This is the definition of S/N adopted by
ALFALFA, which accounts for the fact that for the same peak flux a broader
spectrum has more signal.
Note (7): computed via
MHI/M☉=2.356x105/(1+z) [dL(z)/Mpc]2 (∫Sdv/Jy.km/s)
where dL(z) s the luminosity distance to the galaxy at redshift z as
measured from the HI spectrum.
Note (8): Code 1 refers to reliable detections, with an S/N of the order of 6.5
or higher (this is the same threshold adopted by ALFALFA). Marginal detections
have a lower S/N; thus they have more uncertain HI parameters, but are still
secure detections, with the HI redshift consistent with the SDSS one. The S/N
limit is not strict, but depends also on the HI profile and baseline quality.
As a result, galaxies with an S/N slightly above the threshold but with an
uncertain profile or bad baseline may be flagged with code 2 and objects with
an S/N of ~<6.5 and HI profile with well-defined edges may be classified as
code 1. We assigned quality flag 5 to four 'confused' galaxies, where most of
the HI emission is believed to come from another source within the Arecibo
beam. For some of the galaxies, the presence of small companions within the
beam might contaminate (but is unlikely to dominate) the HI signal - this is
just noted in the Appendix. Finally, we assigned code 3 to GASS 9463, which is
both marginal and confused.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- GASS GASS identification number
7- 25 A19 --- SDSS SDSS designation (JHHMMSS.ss+DDMMSS.s)
27- 32 F6.4 --- z SDSS redshift
34- 35 I2 min Ton On-source integration time of the Arecibo
observation
37- 40 F4.2 mJy rms rms noise of the observation, measured on the
signal- and RFI-free portion of the smoothed
spectrum
42 A1 --- l_logMHI Limit flag on logMHI
43- 46 F4.2 [Msun] logMHI Upper limit of the HI mass (1)
48 A1 --- l_logMHI/M* Limit flag on logMHI/M*
49- 53 F5.2 --- logMHI/M* Upper limit of the HI mass fraction
55 A1 --- Note [*-] An asterisk indicates the presence of a
note for the source in appen.dat file
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Note (1): computed assuming a 5σ signal with 300km/s velocity width,
if the spectrum was smoothed to 150km/s.
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Byte-by-byte Description of file: appen.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- GASS GASS number
7- 80 A74 --- Note Text of the note (1)
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Note (1): AA1 and AA2 are abbreviations for ALFALFA detection codes
1 and 2, respectively.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 21-Mar-2011