[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.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
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.
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 - ULiège > 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.
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