A Lyalpha-only Active Galactic Nucleus from the Sloan Digital Sky Survey
English
Hall, Patrick B[Guest Observer at the Cerro Tololo Inter-American Observatory, a division of the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under cooperative agreement with the National Science Foundation.; Guest Observer at the Canada-France-Hawaii Telescope, a joint facility of the National Research Council of Canada, the Centre National de la Recherche Scientifique of France and the University of Hawaii.; Guest Observer at the La Silla Observatory ESO 3.6 m telescope, for program 071.B-0460.]
Hoversten, Erik A[Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686.]
Tremonti, Christy A[Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721.]
Vanden Berk, Daniel E[Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260.]
Schneider, Donald P[Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802.]
Strauss, Michael A[Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001.]
Knapp, Gillian R[Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001.]
York, Donald G[Department of Astronomy and Astrophysics and Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637.]
Hutsemekers, Damien[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
Newman, P. R.[Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349.]
Brinkmann, J.[Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349.]
Frye, Brenda[Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001.]
Fukugita, Masataka[Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwa, Kashiwa City, Chiba 2778582, Japan.]
Glazebrook, Karl[Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686.]
Harvanek, Michael[Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349.]
Heckman, Timothy M[Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686.]
Ivezic, Zeljko[Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001.]
Kleinman, S.[Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349.]
Krzesinski, Jurek[Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349.; Obserwatorium Astronomiczne na Suhorze, Akademia Pedagogiczna w Krakowie, ulica Podchorazych 2, 30-084 Kraców, Poland.]
Long, Daniel C[Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349.]
Neilsen, Eric[Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510.]
[en] The Sloan Digital Sky Survey has discovered a z=2.4917 radio-loud active galactic nucleus (AGN) with a luminous, variable, low-polarization UV continuum, H I two-photon emission, and a moderately broad Lyalpha line (FWHM~=1430 km s[SUP]-1[/SUP]) but without obvious metal-line emission. SDSS J113658.36+024220.1 does have associated metal-line absorption in three distinct, narrow systems spanning a velocity range of 2710 km s[SUP]-1[/SUP]. Despite certain spectral similarities, SDSS J1136+0242 is not a Lyman break galaxy. Instead, the Lyalpha and two-photon emission can be attributed to an extended, low-metallicity narrow-line region. The unpolarized continuum argues that we see SDSS J1136+0242 very close to the axis of any ionization cone present. We can conceive of two plausible explanations for why we see a strong UV continuum but no broad-line emission in this ``face-on radio galaxy'' model for SDSS J1136+0242: the continuum could be relativistically beamed synchrotron emission that swamps the broad-line emission, or more likely, SDSS J1136+0242 could be similar to PG 1407+265, a quasar in which for some unknown reason the high-ionization emission lines are very broad, very weak, and highly blueshifted.
[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
