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J/ApJ/690/1181            UV-bright quasars                     (Syphers+, 2009)

A high yield of new sightlines for the study of intergalactic helium: Far-UV-Bright quasars from the SDSS, GALEX, and HST. Syphers D., Anderson S.F., Zheng W., Haggard D., Meiksin A., Chiu K., Hogan C., Schneider D.P., York D.G. <Astrophys. J., 690, 1181-1192 (2009)> =2009ApJ...690.1181S
ADC_Keywords: QSOs ; Photometry, ultraviolet ; Redshifts ; Surveys ; Keywords: catalogs - galaxies: active - intergalactic medium - quasars: general - surveys - ultraviolet: galaxies Abstract: Investigations of HeII Lyα (304Å rest-frame) absorption toward a half-dozen quasars at z∼3-4 have demonstrated the great potential of helium studies of the intergalactic medium, but the current critically small sample size of clean sightlines for the HeII Gunn-Peterson test limits confidence in cosmological inferences, and a larger sample is required. Although the unobscured quasar sightlines to high redshift are extremely rare, the Sloan Digital Sky Survey (SDSS) DR6 provides thousands of z>2.8 quasars. We have cross-correlated these SDSS quasars with the Galaxy Evolution Explorer (GALEX) GR2/GR3 to establish a catalog of 200 higher-confidence (∼70% secure) cases of quasars at z=2.8-5.1 potentially having surviving far-UV (rest-frame) flux. We also catalog another 112 likely far-UV-bright quasars from GALEX cross-correlation with other (non-SDSS) quasar compilations. Reconnaissance UV prism observations with the Hubble Space Telescope (HST) of 24 of our SDSS/GALEX candidates confirm 12 as detected in the far-UV, with at least nine having flux extending to very near the HeII break; with refinements our success rate is even higher. Our SDSS/GALEX selection approach is thereby confirmed to be an order of magnitude more efficient than previous HeII quasar searches, more than doubles the number of spectroscopically confirmed clean sightlines to high redshift, and provides a resource list of hundreds of high-confidence sightlines for upcoming HeII and other far-UV studies from the HST. Our reconnaissance HST prism spectra suggest some far-UV diversity, confirming the need to obtain a large sample of independent quasar sightlines across a broad redshift range to assess such issues as the epoch(s) of helium reionization, while averaging over individual-object pathology and/or cosmic variance. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 74 200 Catalog of candidate Far-UV-Bright SDSS/GALEX quasars table2.dat 62 112 Catalog of candidate Far-UV-Bright (non-SDSS) VCV/GALEX quasars
See also: II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010) J/AJ/133/1780 : GALEX/SDSS quasar catalog (Trammell+, 2007) J/ApJ/664/53 : UV photometry of GALEX QSO candidates (Atlee+, 2007) J/ApJS/185/20 : Additional HeII quasar sightlines (Syphers+, 2009) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [SDSS] 5- 23 A19 --- SDSS SDSS DR6 name ( 25- 34 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000) 36- 45 F10.6 deg DEdeg Declination in decimal degrees (J2000) 47- 50 F4.2 --- z SDSS pipeline redshift (photometric) 52- 56 F5.2 mag zmag SDSS z-band magnitude 58- 63 F6.3 10-19W/m2/nm NUV ? GALEX NUV flux (177-300nm) 65- 70 F6.3 10-19W/m2/nm FUV ? GALEX FUV flux (120-177nm) 72 I1 --- Insp [0/8] Inspection flag (1) 74 I1 --- Obs [0/2] Prior observation flag (G2)
Note (1): 4-bit integer flag. These individual flags are additive for a given object (e.g., 6 denotes a BAL with an LLS or DLA). Flags as follows: 1 = very near neighbor in the SDSS image 2 = probable LLS or DLA in the SDSS spectrum 3 = very near neighbor in the SDSS image and probable LLS or DLA in the SDSS spectrum 4 = BAL (Broad Absorption Line) 5 = BAL with very near neighbor in the SDSS image 6 = BAL with probable LLS or DLA in the SDSS spectrum 8 = possible BAL
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 16 A16 --- Name Veron-Cetty & Veron (VCV) name (Cat. VII/258) 18- 25 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000) 27- 34 F8.4 deg DEdeg Declination in decimal degrees (J2000) 36- 40 F5.3 --- z VCV redshift (spectroscopic) 42 A1 --- f_Vmag Flag on Vmag (1) 43- 47 F5.2 mag Vmag VCV V-band magnitude 49- 53 F5.2 10-19W/m2/nm NUV ? GALEX NUV flux (177-300nm) 55- 60 F6.2 10-19W/m2/nm FUV ? GALEX FUV flux (120-177nm) 62 I1 --- Obs [0/2] Prior observation flag (G2)
Note (1): V magnitude unless otherwise marked as follows: * = photographic B = blue R = red I = infrared J = infrared K = infrared O = photographic O-plate J = photographic J-plate
Global notes: Note (G2): Flags as follows: 0 = object has not been observed with HST 1 = object has been observed with FUV (to near 304Å rest) spectroscopy through HST cycle 16 2 = object has been observed less conclusively, i.e., NUV spectroscopy, UV imaging, or pre-COSTAR observation
History: From electronic version of the journal References: Syphers et al., Paper II 2009ApJS..185...20S Cat. J/ApJS/185/20
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Mar-2010
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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