Browsing by Author "Voges, W"
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- ItemA large, uniform sample of X-ray-emitting AGNs(2003) Anderson, SF; Voges, W; Margon, B; Trümper, J; Agüeros, MA; Boller, T; Collinge, MJ; Homer, L; Stinson, G; Strauss, MA; Annis, J; Gómez, P; Hall, PB; Nichol, RC; Richards, GT; Schneider, DP; Vanden Berk, DE; Fan, XH; Ivezic, Z; Munn, JA; Newberg, HJ; Richmond, MW; Weinberg, DH; Yanny, B; Bahcall, NA; Brinkmann, J; Fukugita, M; York, DGMany open questions in X-ray astronomy are limited by the relatively small number of objects in uniform optically identified and observed samples, especially when rare subclasses are considered or when subsets are isolated to search for evolution or correlations between wavebands. We describe the initial results of a new program aimed to ultimately yield similar to10(4) fully characterized X-ray source identifications-a sample about an order of magnitude larger than earlier efforts. The technique is detailed and employs X-ray data from the ROSAT All-Sky Survey (RASS) and optical imaging and spectroscopic follow-up from the Sloan Digital Sky Survey (SDSS); these two surveys prove to be serendipitously very well matched in sensitivity. As part of the SDSS software pipelines, optical objects in the SDSS photometric catalogs are automatically positionally cross-correlated with RASS X-ray sources. Then priorities for follow-on SDSS optical spectra of candidate counterparts are automatically assigned using an algorithm based on the known ratios of f(x)/f(opt) for various classes of X-ray emitters at typical RASS fluxes of similar to10(-13) ergs cm(-2) s(-1). SDSS photometric parameters for optical morphology, magnitude, and colors, plus FIRST radio information, serve as proxies for object class. Initial application of this approach to RASS/SDSS data from 1400 deg(2) of sky provides a catalog of more than 1200 spectroscopically confirmed quasars and other AGNs that are probable RASS identifications. Most of these are new identifications, and only a few percent of the AGN counterparts are likely to be random superpositions. The magnitude and redshift ranges of the counterparts are very broad, extending over 15
- ItemDouble-peaked low-ionization emission lines in active galactic nuclei(2003) Strateva, IV; Strauss, MA; Hao, L; Schlegel, DJ; Hall, PB; Gunn, JE; Li, LX; Ivezic, Z; Richards, GT; Zakamska, NL; Voges, W; Anderson, SF; Lupton, RH; Schneider, DP; Brinkmann, J; Nichol, RCWe present a new sample of 116 double-peaked Balmer line active galactic nuclei (AGNs) selected from the Sloan Digital Sky Survey. Double-peaked emission lines are believed to originate in the accretion disks of AGNs, a few hundred gravitational radii (R-G) from the supermassive black hole. We investigate the properties of the candidate disk emitters with respect to the full sample of AGNs over the same redshifts, focusing on optical, radio, and X-ray flux, broad-line shapes and narrow-line equivalent widths, and line flux ratios. We find that the disk emitters have medium luminosities (similar to10(44) ergs s(-1)) and FWHM on average 6 times broader than the AGNs in the parent sample. The double-peaked AGNs are 1.6 times more likely to be radio sources and are predominantly (76%) radio-quiet, with about 12% of the objects classified as LINERs. Statistical comparison of the observed double-peaked line profiles with those produced by axisymmetric and nonaxisymmetric accretion disk models allows us to impose constraints on accretion disk parameters. The observed Halpha line profiles are consistent with accretion disks with inclinations smaller than 50degrees, surface emissivity slopes of 1.0-2.5, outer radii larger than similar to2000R(G), inner radii of (200-800) R-G, and local turbulent broadening of 780-1800 km s(-1). The comparison suggests that 60% of accretion disks require some form of asymmetry ( e. g., elliptical disks, warps, spiral shocks, or hot spots).
- ItemOptical and radio properties of extragalactic sources observed by the first survey and the Sloan Digital Sky Survey(2002) Ivezic, Z; Menou, K; Knapp, GR; Strauss, MA; Lupton, RH; Vanden Berk, DE; Richards, GT; Tremonti, C; Weinstein, MA; Anderson, S; Bahcall, NA; Becker, RH; Bernardi, M; Blanton, M; Eisenstein, D; Fan, XH; Finkbeiner, D; Finlator, K; Frieman, J; Gunn, JE; Hall, PB; Kim, RSJ; Kinkhabwala, A; Narayanan, VK; Rockosi, CM; Schlegel, D; Schneider, DP; Strateva, I; SubbaRao, M; Thakar, AR; Voges, W; White, RL; Yanny, B; Brinkmann, J; Doi, M; Fukugita, M; Hennessy, GS; Munn, JA; Nichol, RC; York, DGWe discuss the optical and radio properties of similar to30,000 FIRST (radio, 20 cm, sensitive to 1 mJy) sources positionally associated within 1."5 with a Sloan Digital Sky Survey (SDSS) (optical, sensitive to r*similar to22.2) source in 1230 deg(2) of sky. The matched sample represents similar to30% of the 108,000 FIRST sources and 0.1% of the 2.5x10(7) SDSS sources in the studied region. SDSS spectra are available for 4300 galaxies and 1154 quasars from the matched sample and for a control sample of 140,000 galaxies and 20, 000 quasars in 1030 deg(2) of sky. Here we analyze only core sources, which dominate the sample; the fraction of SDSS-FIRST sources with complex radio morphology is determined to be less than 10%. This large and unbiased catalog of optical identifications provides much firmer statistical footing for existing results and allows several new findings. The majority (83%) of the FIRST sources identified with an SDSS source brighter than r*=21 are optically resolved; the fraction of resolved objects among the matched sources is a function of the radio flux, increasing from similar to50% at the bright end to similar to90% at the FIRST faint limit. Nearly all optically unresolved radio sources have nonstellar colors indicative of quasars. We estimate an upper limit of similar to5% for the fraction of quasars with broadband optical colors indistinguishable from those of stars. The distribution of quasars in the radio flux optical flux plane suggests the existence of the "quasar radio dichotomy" 8%+/-1% of all quasars with i*<18.5 are radio-loud, and this fraction seems independent of redshift and optical luminosity. The radio-loud quasars have a redder median color by 0.08±0.02 mag, and show a 3 times larger fraction of objects with extremely red colors. FIRST galaxies represent 5% of all SDSS galaxies with r*<17.5, and 1% for r*<20, and are dominated by red (u*-r*>2.22) galaxies, especially those with r*>17.5. Magnitude- and redshift-limited samples show that radio galaxies have a different optical luminosity distribution than nonradio galaxies selected by the same criteria; when galaxies are further separated by their colors, this result remains valid for both blue and red galaxies. For a given optical luminosity and redshift, the observed optical colors of radio galaxies are indistinguishable from those of all SDSS galaxies selected by identical criteria. The distributions of radio-to-optical flux ratio are similar for blue and red galaxies in redshift-limited samples; this similarity implies that the difference in their luminosity functions and resulting selection effects are the dominant cause for the preponderance of red radio galaxies in flux-limited samples. The fraction of radio galaxies whose emission-line ratios indicate an AGN(30%), rather than starburst, origin is 6 times larger than the corresponding fraction for all SDSS galaxies (r*<17.5). We confirm that the AGN-to-starburst galaxy number ratio increases with radio flux and find that radio emission from AGNs is more concentrated than radio emission from starburst galaxies.
- ItemSloan Digital Sky Survey(2002) Stoughton, C; Lupton, RH; Bernardi, M; Blanton, MR; Burles, S; Castander, FJ; Connolly, AJ; Eisenstein, DJ; Frieman, JA; Hennessy, GS; Hindsley, RB; Ivezic, Z; Kent, S; Kunszt, PZ; Lee, BC; Meiksin, A; Munn, JA; Newberg, HJ; Nichol, RC; Nicinski, T; Pier, JR; Richards, GT; Richmond, MW; Schlegel, DJ; Smith, JA; Strauss, MA; SubbaRao, M; Szalay, AS; Thakar, AR; Tucker, DL; Vanden Berk, DE; Yanny, B; Adelman, JK; Anderson, JE; Anderson, SF; Annis, J; Bahcall, NA; Bakken, JA; Bartelmann, M; Bastian, S; Bauer, A; Berman, E; Böhringer, H; Boroski, WN; Bracker, S; Briegel, C; Briggs, JW; Brinkmann, J; Brunner, R; Carey, L; Carr, MA; Chen, B; Christian, D; Colestock, PL; Crocker, JH; Csabai, IN; Czarapata, PC; Dalcanton, J; Davidsen, AF; Davis, JE; Dehnen, W; Dodelson, S; Doi, M; Dombeck, T; Donahue, M; Ellman, N; Elms, BR; Evans, ML; Eyer, L; Fan, XH; Federwitz, GR; Friedman, S; Fukugita, M; Gal, R; Gillespie, B; Glazebrook, K; Gray, J; Grebel, EK; Greenawalt, B; Greene, G; Gunn, JE; de Haas, E; Haiman, Z; Haldeman, M; Hall, PB; Hamabe, M; Hansen, B; Harris, FH; Harris, H; Harvanek, M; Hawley, SL; Hayes, JJE; Heckman, TM; Helmi, A; Henden, A; Hogan, CJ; Hogg, DW; Holmgren, DJ; Holtzman, J; Huang, CH; Hull, C; Ichikawa, SI; Ichikawa, T; Johnston, DE; Kauffmann, G; Kim, RSJ; Kimball, T; Kinney, E; Klaene, M; Kleinman, SJ; Klypin, A; Knapp, GR; Korienek, J; Krolik, J; Kron, RG; Krzesinski, J; Lamb, DQ; Leger, RF; Limmongkol, S; Lindenmeyer, C; Long, DC; Loomis, C; Loveday, J; MacKinnon, B; Mannery, EJ; Mantsch, PM; Margon, B; McG'hee, P; Mckay, TA; McLean, B; Menou, K; Merelli, A; Mo, HJ; Monet, DG; Nakamura, O; Narayanan, VK; Nash, T; Neilsen, EH; Newman, PR; Nitta, A; Odenkirchen, M; Okada, N; Okamura, S; Ostriker, JP; Owen, R; Pauls, AG; Peoples, J; Peterson, RS; Petravick, D; Pope, A; Pordes, R; Postman, M; Prosapio, A; Quinn, TR; Rechenmacher, R; Rivetta, CH; Rix, HW; Rockosi, CM; Rosner, R; Ruthmansdorfer, K; Sandford, D; Schneider, DP; Scranton, R; Sekiguchi, M; Sergey, G; Sheth, R; Shimasaku, K; Smee, S; Snedden, SA; Stebbins, A; Stubbs, C; Szapudi, I; Szkody, P; Szokoly, GP; Tabachnik, S; Tsvetanov, Z; Uomoto, A; Vogeley, MS; Voges, W; Waddell, P; Walterbos, R; Wang, SI; Watanabe, M; Weinberg, DH; White, RL; White, SDM; Wilhite, B; Wolfe, D; Yasuda, N; York, DG; Zehavi, I; Zheng, WThe Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere and collect spectra of 10 6 galaxies, 100,000 quasars, 30,000 stars, and 30,000 serendipity targets. In 2001 June, the SDSS released to the general astronomical community its early data release, roughly 462 deg(2) of imaging data including almost 14 million detected objects and 54,008 follow-up spectra. The imaging data were collected in drift-scan mode in five bandpasses (u, g, r, i, and z); our 95% completeness limits for stars are 22.0, 22.2, 22.2, 21.3, and 20.5, respectively. The photometric calibration is reproducible to 5%, 3%, 3%, 3%, and 5%, respectively. The spectra are flux- and wavelength-calibrated, with 4096 pixels from 3800 to 9200 Angstrom at R approximate to 1800. We present the means by which these data are distributed to the astronomical community, descriptions of the hardware used to obtain the data, the software used for processing the data, the measured quantities for each observed object, and an overview of the properties of this data set.
- ItemThe first data release of the Sloan Digital Sky Survey(2003) Abazajian, K; Adelman-McCarthy, JK; Agüeros, MA; Allam, SS; Anderson, SF; Annis, J; Bahcall, NA; Baldry, IK; Bastian, S; Berlind, A; Bernardi, M; Blanton, MR; Blythe, N; Bochanski, JJ; Boroski, WN; Brewington, H; Briggs, JW; Brinkmann, J; Brunner, RJ; Budavári, T; Carey, LN; Carr, MA; Castander, FJ; Chiu, K; Collinge, MJ; Connolly, AJ; Covey, KR; Csabai, I; Dalcanton, JJ; Dodelson, S; Doi, M; Dong, F; Eisenstein, DJ; Evans, ML; Fan, XH; Feldman, PD; Finkbeiner, DP; Friedman, SD; Frieman, JA; Fukugita, M; Gal, RR; Gillespie, B; Glazebrook, K; Gonzalez, CF; Gray, J; Grebel, EK; Grodnicki, L; Gunn, JE; Gurbani, VK; Hall, PB; Hao, L; Harbeck, D; Harris, FH; Harris, HC; Harvanek, M; Hawley, SL; Heckman, TM; Helmboldt, JF; Hendry, JS; Hennessy, GS; Hindsley, RB; Hogg, DW; Holmgren, DJ; Holtzman, JA; Homer, L; Hui, L; Ichikawa, SI; Ichikawa, T; Inkmann, JP; Ivezic, Z; Jester, S; Johnston, DE; Jordan, B; Jordan, WP; Jorgensen, AM; Juric, M; Kauffmann, G; Kent, SM; Kleinman, SJ; Knapp, GR; Kniazev, AY; Kron, RG; Krzesinski, J; Kunszt, PZ; Kuropatkin, N; Lamb, DQ; Lampeitl, H; Laubscher, BE; Lee, BC; Leger, RF; Li, N; Lidz, A; Lin, H; Loh, YS; Long, DC; Loveday, J; Lupton, RH; Malik, T; Margon, B; McGehee, PM; McKay, TA; Meiksin, A; Miknaitis, GA; Moorthy, BK; Munn, JA; Murphy, T; Nakajima, R; Narayanan, VK; Nash, T; Neilsen, EH; Newberg, HJ; Newman, PR; Nichol, RC; Nicinski, T; Nieto-Santisteban, M; Nitta, A; Odenkirchen, M; Okamura, S; Ostriker, JP; Owen, R; Padmanabhan, N; Peoples, J; Pier, JR; Pindor, B; Pope, AC; Quinn, TR; Rafikov, RR; Raymond, SN; Richards, GT; Richmond, MW; Rix, HW; Rockosi, CM; Schaye, J; Schlegel, DJ; Schneider, DP; Schroeder, J; Scranton, R; Sekiguchi, M; Seljak, U; Sergey, G; Sesar, B; Sheldon, E; Shimasaku, K; Siegmund, WA; Silvestri, NM; Sinisgalli, AJ; Sirko, E; Smith, JA; Smolcic, V; Snedden, SA; Stebbins, A; Steinhardt, C; Stinson, G; Stoughton, C; Strateva, IV; Strauss, MA; Subbarao, M; Szalay, AS; Szapudi, I; Szkody, P; Tasca, L; Tegmark, M; Thakar, AR; Tremonti, C; Tucker, DL; Uomoto, A; Vanden Berk, DE; Vandenberg, J; Vogeley, MS; Voges, W; Vogt, NP; Walkowicz, LM; Weinberg, DH; West, AA; White, SDM; Wilhite, BC; Willman, B; Xu, YZ; Yanny, B; Yarger, J; Yasuda, N; Yip, CW; Yocum, DR; York, DG; Zakamska, NL; Zehavi, I; Zheng, W; Zibetti, S; Zucker, DBThe Sloan Digital Sky Survey (SDSS) has validated and made publicly available its First Data Release. This consists of 2099 deg(2) of five-band (u, g, r, i, z) imaging data, 186,240 spectra of galaxies, quasars, stars and calibrating blank sky patches selected over 1360 deg(2) of this area, and tables of measured parameters from these data. The imaging data go to a depth of r approximate to 22.6 and are photometrically and astrometrically calibrated to 2% rms and 100 mas rms per coordinate, respectively. The spectra cover the range 3800-9200 Angstrom, with a resolution of 1800-2100. This paper describes the characteristics of the data with emphasis on improvements since the release of commissioning data (the SDSS Early Data Release) and serves as a pointer to extensive published and on-line documentation of the survey.
- ItemThe Sloan Digital Sky Survey Quasar Catalog. I. Early data release(2002) Schneider, DP; Richards, GT; Fan, XH; Hall, PB; Strauss, MA; Vanden Berk, DE; Gunn, JE; Newberg, HJ; Reichard, TA; Stoughton, C; Voges, W; Yanny, B; Anderson, SF; Annis, J; Bahcall, NA; Bauer, A; Bernardi, M; Blanton, MR; Boroski, WN; Brinkmann, J; Briggs, JW; Brunner, R; Burles, S; Carey, L; Castander, FJ; Connolly, AJ; Csabai, I; Doi, M; Friedman, S; Frieman, JA; Fukugita, M; Heckman, TM; Hennessy, GS; Hindsley, RB; Hogg, DW; Ivezic, Z; Kent, S; Knapp, GR; Kunzst, PZ; Lamb, DQ; Leger, RF; Long, DC; Loveday, J; Lupton, RH; Margon, B; Meiksin, A; Merelli, A; Munn, JA; Newcomb, M; Nichol, RC; Owen, R; Pier, JR; Pope, A; Rockosi, CM; Saxe, DH; Schlegel, D; Siegmund, WA; Smee, S; Snir, Y; SubbaRao, M; Szalay, AS; Thakar, AR; Uomoto, A; Waddell, P; York, DGWe present the first edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog. The catalog consists of the 3814 objects ( 3000 discovered by the SDSS) in the initial SDSS public data release that have at least one emission line with a full width at half-maximum larger than 1000 km s(-1), luminosities brighter than M(i*) = -23, and highly reliable redshifts. The area covered by the catalog is 494 deg(2); the majority of the objects were found in SDSS commissioning data using a multicolor selection technique. The quasar redshifts range from 0.15 to 5.03. For each object the catalog presents positions accurate to better than 0".2 rms per coordinate, five-band (ugriz) CCD-based photometry with typical accuracy of 0.05 mag, radio and X-ray emission properties, and information on the morphology and selection method. Calibrated spectra of all objects in the catalog, covering the wavelength region 3800-9200 Angstrom at a spectral resolution of 1800-2100, are also available. Since the quasars were selected during the commissioning period, a time when the quasar selection algorithm was undergoing frequent revisions, the sample is not homogeneous and is not intended for statistical analysis.
- ItemThe Sloan Digital Sky Survey Quasar Catalog. II. First data release(2003) Schneider, DP; Fan, XH; Hall, PB; Jester, S; Richards, GT; Stoughton, C; Strauss, MA; SubbaRao, M; Vanden Berk, DE; Anderson, SF; Brandt, WN; Gunn, JE; Gray, J; Trump, JR; Voges, W; Yanny, B; Bahcall, NA; Blanton, MR; Boroski, WN; Brinkmann, J; Brunner, R; Burles, S; Castander, FJ; Doi, M; Eisenstein, D; Frieman, JA; Fukugita, M; Heckman, TM; Hennessy, GS; Ivezic, Z; Kent, S; Knapp, GR; Lamb, DQ; Lee, BC; Loveday, J; Lupton, RH; Margon, B; Meiksin, A; Munn, JA; Newberg, HJ; Nichol, RC; Niederste-Ostholt, M; Pier, JR; Richmond, MW; Rockosi, CM; Saxe, DH; Schlegel, DJ; Szalay, AS; Thakar, AR; Uomoto, A; York, DGWe present the second edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog. The catalog consists of the 16,713 objects in the SDSS First Data Release that have luminosities larger than M-i=-22 (in a cosmology with H-0=70 km s(-1) Mpc(-1), Omega(M)=0.3, and Omega(Lambda)=0.7), have at least one emission line with FWHM larger than 1000 km s(-1), and have highly reliable redshifts. The area covered by the catalog is approximate to1360 deg(2). The quasar redshifts range from 0.08 to 5.41, with a median value of 1.43. For each object, the catalog presents positions accurate to better than 0."2 rms per coordinate, five- band (ugriz) CCD-based photometry with typical accuracy of 0.03 mag, and information on the morphology and selection method. The catalog also contains some radio, near-infrared, and X-ray emission properties of the quasars, when available, from other large-area surveys. Calibrated digital spectra of all objects in the catalog, covering the wavelength region 3800-9200 Angstrom at a spectral resolution of 1800-2100, are available. This publication supersedes the first SDSS Quasar Catalog, which was based on material from the SDSS Early Data Release. A summary of corrections to current quasar databases is also provided. The majority of the objects were found in SDSS commissioning data using a multicolor selection technique. Since the quasar selection algorithm was undergoing testing during the entire observational period covered by this catalog, care must be taken when assembling samples from the catalog for use in statistical studies. A total of 15,786 objects (94%) in the catalog were discovered by the SDSS; 12,173 of the SDSS discoveries are reported here for the first time. Included in the new discoveries are five quasars brighter than i=16.0 and 17 quasars with redshifts larger than 4.5.