Browsing by Author "Brunner, RJ"

Now showing 1 - 4 of 4
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    Peculiar broad absorption line quasars found in the digitized palomar observatory sky survey
    (2003) Brunner, RJ; Hall, PB; Djorgovski, SG; Gal, RR; Mahabal, AA; Lopes, PAA; de Carvalho, RR; Odewahn, SC; Castro, S; Thompson, D
    With the recent release of large (i.e., greater than or similar to 100 million objects), well-calibrated photometric surveys, such as Digitized Palomar Observatory Sky Survey (DPOSS), Two Micron All Sky Survey, and Sloan Digital Sky Survey, spectroscopic identification of important targets is no longer a simple issue. In order to enhance the returns from a spectroscopic survey, candidate sources are often preferentially selected to be of interest, such as brown dwarfs or high-redshift quasars. This approach, while useful for targeted projects, risks missing new or unusual species. We have, as a result, taken the alternative path of spectroscopically identifying interesting sources with the sole criterion being that they are in low-density areas of the g-r and r-i color space defined by DPOSS. In this paper, we present three peculiar broad absorption line quasars that were discovered during this spectroscopic survey, demonstrating the efficacy of this approach. PSS J0052+2405 is an iron low-ionization broad absorption line (LoBAL) quasar at a redshift z = 2.4512-0.0001 with very broad absorption from many species. PSS J0141+3334 is a reddened LoBAL quasar at z = 3.005 +/- 0.005 with no obvious emission lines. PSS J1537+1227 is an iron LoBAL at a redshift of z = 1.212 +/- 0.007 with strong narrow Mg II and Fe II emission. Follow-up high-resolution spectroscopy of these three quasars promises to improve our understanding of BAL quasars. The sensitivity of particular parameter spaces, in this case a two-color space, to the redshift of these three sources is dramatic, raising questions about traditional techniques of de. ning quasar populations for statistical analysis.
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    Tests of the accelerating universe with near-infrared observations of a high-redshift type Ia supernova
    (2000) Riess, AG; Filippenko, AV; Liu, MC; Challis, P; Clocchiatti, A; Diercks, A; Garnavich, PM; Hogan, CJ; Jha, S; Kirshner, RP; Leibundgut, B; Phillips, MM; Reiss, D; Schmidt, BP; Schommer, RA; Smith, RC; Spyromilio, J; Stubbs, C; Suntzeff, NB; Tonry, J; Woudt, P; Brunner, RJ; Dey, A; Gal, R; Graham, J; Larkin, J; Odewahn, SC; Oppenheimer, B
    We have measured the rest-frame B-, V-, and I-band light curves of a high-redshift type Ia supernova (SN 1a), SN 1999Q (z = 0.46), using the Hubble Space Telescope (HST) and ground-based near-infrared detectors. A goal of this study is the measurement of the color excess, EB-I, a sensitive indicator of interstellar or intergalactic dust, which could affect recent cosmological measurements from high-redshift SNe Ia. Our observations disfavor a 30% opacity of SN Ia visual light by dust as an alternative to an accelerating universe. This statement applies to both Galactic-type dust (rejected at the 3.4 sigma confidence level) and grayer dust (grain size > 0.1 mu m, rejected at the 2.3-2.6 sigma confidence level) as proposed by Aguirre. The rest-frame I-band light curve shows the secondary maximum 1 month after the B maximum typical of nearby SNe fa of normal luminosity, providing no indication of evolution as a function of redshift out to z approximate to 0.5. An expanded set of similar observations could improve the constraints on any contribution of extragalactic dust to the dimming of high-redshift SNe Ia.
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    The ensemble photometric variability of ∼25,000 quasars in the Sloan Digital Sky Survey
    (2004) Berk, DEV; Wilhite, BC; Kron, RG; Anderson, SF; Brunner, RJ; Hall, PB; Ivezic, Z; Richards, GT; Schneider, DP; York, DG; Brinkmann, JV; Lamb, DQ; Nichol, RC; Schlegel, DJ
    Using a sample of over 25,000 spectroscopically confirmed quasars from the Sloan Digital Sky Survey, we show how quasar variability in the rest-frame optical/UV regime depends on rest-frame time lag, luminosity, rest wavelength, redshift, the presence of radio and X-ray emission, and the presence of broad absorption line systems. Imaging photometry is compared with three-band spectrophotometry obtained at later epochs spanning time lags up to about 2 yr. The large sample size and wide range of parameter values allow the dependence of variability to be isolated as a function of many independent parameters. The time dependence of variability (the structure function) is well fitted by a single power law with an index gamma=0.246+/-0.008, on timescales from days to years. There is an anticorrelation of variability amplitude with rest wavelength-e.g., quasars are about twice as variable at 1000 Angstrom as at 6000 Angstrom-and quasars are systematically bluer when brighter at all redshifts. There is a strong anticorrelation of variability with quasar luminosity-variability amplitude decreases by a factor of about 4 when luminosity increases by a factor of 100. There is also a significant positive correlation of variability amplitude with redshift, indicating evolution of the quasar population or the variability mechanism. We parameterize all of these relationships. Quasars with ROSAT All-Sky Survey X-ray detections are significantly more variable (at optical/UV wavelengths) than those without, and radio-loud quasars are marginally more variable than their radio-quiet counterparts. We find no significant difference in the variability of quasars with and without broad absorption line troughs. Currently, no models of quasar variability address more than a few of these relationships. Models involving multiple discrete events or gravitational microlensing are unlikely by themselves to account for the data. So-called accretion disk instability models are promising, but more quantitative predictions are needed.
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    The 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, DB
    The 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.