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J/ApJ/808/136  UV counterparts in HI clouds using ALFA surveys  (Donovan+, 2015)

Finding gas-rich dwarf galaxies betrayed by their ultraviolet emission. Donovan Meyer J., Peek J.E.G., Putman M., Grcevich J. <Astrophys. J., 808, 136 (2015)> =2015ApJ...808..136D (SIMBAD/NED BibCode)
ADC_Keywords: Diffuse clouds ; H I data ; Photometry, ultraviolet Keywords: catalogs - galaxies: dwarf - Local Group - ultraviolet: galaxies Abstract: We present ultraviolet (UV) follow-up of a sample of potential dwarf galaxy candidates selected for their neutral hydrogen (HI) properties, taking advantage of the low UV background seen by the GALEX satellite and its large and publicly available imaging footprint. The HI clouds, which are drawn from published Galactic Arecibo L-band Feed Array and Arecibo Legacy Fast Arecibo L-band Feed Array HI survey compact cloud catalogs, are selected to be galaxy candidates based on their spatial compactness and non-association with known high-velocity cloud complexes or Galactic HI emission. Based on a comparison of their UV characteristics to those of known dwarf galaxies, half (48%) of the compact HI clouds have at least one potential stellar counterpart with UV properties similar to those of nearby dwarf galaxies. If they are galaxies, then the star formation rates, HI masses, and star formation efficiencies of these systems follow the trends seen for much larger galaxies. The presence of UV emission is an efficient method to identify the best targets for spectroscopic follow-up, which is necessary to prove that the stars are associated with compact HI. Furthermore, searches of this nature help to refine the salient HI properties of likely dwarfs (even beyond the Local Group). In particular, HI compact clouds considered to be velocity outliers relative to their neighbor HI clouds have the most significant detection rate of single, appropriate UV counterparts. Correcting for the sky coverage of the two all-Arecibo sky surveys yielding the compact HI clouds, these results may imply the presence of potentially hundreds of new tiny galaxies across the entire sky. Description: GALFA-HI is a survey of Galactic HI conducted with the ALFA seven-beam feed array on the 305 m Arecibo antenna. The survey has both high spatial (FWHM∼4') and velocity (0.18 km/s) resolution over 13000 (7520 in DR1) degrees2 of sky between -650 and 650 km/s. Details of the observations and data reduction can be found in Peek et al. (2011ApJS..194...20P). The ALFALFA HI-line survey, now 40% complete, also uses the Arecibo Observatory and its seven-beam feed array to detect potential dwarf galaxies in the vicinity of the Milky Way. The survey, which covers over 7000 (2800 in α.40) deg2 of sky out to 18000 km/s, has the sensitivity to detect 105 M clouds with 20 km/s linewidths at a distance of 1 Mpc. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 87 98 Summary of HI Clouds table2.dat 92 29 Single Counterpart Candidates (SCCs)
See also: J/AJ/138/338 : Arecibo Legacy Fast ALFA Survey. IX. (Stierwalt+, 2009) J/ApJ/722/395 : Compact H I clouds from the GALFA-H I survey (Begum+, 2010) J/AJ/142/170 : ALFALFA survey: the α.40 HI source catalog (Haynes+, 2011) J/ApJS/192/6 : A GALEX UV imaging survey of nearby galaxies (Lee+, 2011) J/AJ/143/133 : Properties of dwarf galaxies from the ALFALFA survey (Huang+, 2012) J/ApJ/758/44 : The GALFA-HI compact cloud catalog (Saul+, 2012) J/ApJ/768/77 : Ultra-compact high velocity clouds from ALFALFA (Adams+, 2013) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Number [1/98] Cloud number 4- 12 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000) 14- 21 F8.5 deg DEdeg Declination in decimal degrees (J2000) 23- 26 I4 km/s VLSR Local Standard of Rest velocity 28- 31 I4 km/s VGSR Galactic Standard of Rest velocity 33- 36 I4 km/s VLGSR Local Group Standard of Rest velocity 38- 41 F4.2 Jy.km/s SHI Integrated HI flux density 43- 46 F4.1 arcmin Size Size 48- 51 F4.1 km/s FWHM FWHM of the HI line 53- 56 F4.1 --- S/N HI signal-to-noise ratio 58- 61 I4 s tNUV NUV exposure time 63- 66 I4 s tFUV FUV exposure time 68- 85 A18 --- Cat Compact cloud catalog containing detection (1) 87 I1 --- Group [0/2]? Group of detected UV counterparts (2)
Note (1): Catalog as follows: S12 = Saul et al. 2012, J/ApJ/758/44; G14 = Grcevich et al. submitted; A13 = Adams et al. 2013, J/ApJ/768/77. The GALFA-HI catalogs are broken down further into the detection methods, as follows: HI = High HI column density; S/N = High S/N list; VEL = Velocity outliers. Note (2): Group as follows: 0 = Zero counterparts; 1 = One counterpart, or "single counterpart candidates" (SCC); 2 = Multiple counterparts.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Number [1/88] Cloud number 4- 11 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000) 13- 20 F8.5 deg DEdeg Declination in decimal degrees (J2000) 22- 26 F5.2 mag NUVmag GALEX NUV AB magnitude 28- 31 F4.2 mag e_NUVmag Uncertainty in NUVmag 33- 37 F5.2 mag FUVmag GALEX FUV AB magnitude 39- 42 F4.2 mag e_FUVmag Uncertainty in FUVmag 44- 48 F5.2 arcsec MajAxis Major axis size 50- 54 F5.2 arcsec MinAxis Minor axis size 56- 58 F3.1 Mpc b_Dist Distance range, lower value 60- 63 F4.1 Mpc B_Dist Distance range, upper value 65- 67 F3.1 10+6Msun b_MHI HI mass range, lower value 69- 73 F5.1 10+6Msun B_MHI HI mass range, upper value 75- 78 F4.1 10-5Msun/yr b_SFR Star Formation Rate range, lower value 80- 85 F6.1 10-5Msun/yr B_SFR Star Formation Rate range, upper value 87- 92 F6.1 10-12/yr SFE Star Formation Efficiency (SFE=SFR/MHI)
History: From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 27-Oct-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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