1 Ocak 2017 Dergi makalesi Açık Erişim

McGraw, S. M.; Brandt, W. N.; Grier, C. J.; Ak, N. Filiz; Hall, P. B.; Schneider, D. P.; Anderson, S. F.; Green, P. J.; Hutchinson, T. A.; Macleod, C. L.; Vivek, M.

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  "@context": "https://schema.org/", 
  "@id": 45141, 
  "@type": "ScholarlyArticle", 
  "creator": [
    {
      "@type": "Person", 
      "name": "McGraw, S. M."
    }, 
    {
      "@type": "Person", 
      "name": "Brandt, W. N."
    }, 
    {
      "@type": "Person", 
      "name": "Grier, C. J."
    }, 
    {
      "@type": "Person", 
      "name": "Ak, N. Filiz"
    }, 
    {
      "@type": "Person", 
      "affiliation": "York Univ, Dept Phys & Astron, 4700 Keele St, Toronto, ON M3J 1P3, Canada", 
      "name": "Hall, P. B."
    }, 
    {
      "@type": "Person", 
      "name": "Schneider, D. P."
    }, 
    {
      "@type": "Person", 
      "affiliation": "Univ Washington, Dept Astron, Box 351580, Seattle, WA 98195 USA", 
      "name": "Anderson, S. F."
    }, 
    {
      "@type": "Person", 
      "affiliation": "Harvard Smithsonian Ctr Astrophys, 60 Garden Sreet, Cambridge, MA 02138 USA", 
      "name": "Green, P. J."
    }, 
    {
      "@type": "Person", 
      "affiliation": "Univ Utah, Dept Phys & Astron, 115 S 1400 E, Salt Lake City, UT 84112 USA", 
      "name": "Hutchinson, T. A."
    }, 
    {
      "@type": "Person", 
      "affiliation": "Harvard Smithsonian Ctr Astrophys, 60 Garden Sreet, Cambridge, MA 02138 USA", 
      "name": "Macleod, C. L."
    }, 
    {
      "@type": "Person", 
      "affiliation": "Univ Utah, Dept Phys & Astron, 115 S 1400 E, Salt Lake City, UT 84112 USA", 
      "name": "Vivek, M."
    }
  ], 
  "datePublished": "2017-01-01", 
  "description": "We investigate broad absorption line (BAL) disappearance and emergence using a 470 BAL-quasar sample over <= 0.10-5.25 rest-frame years with at least three spectroscopic epochs for each quasar from the Sloan Digital Sky Survey. We identify 14 disappearing BALs over <= 1.73-4.62 rest-frame years and 18 emerging BALs over <= 1.46-3.66 rest-frame years associated with the C IV lambda 1548,1550 and/or Si IV lambda lambda 1393,1402 doublets, and report on their variability behaviour. BAL quasars in our data set exhibit disappearing/emerging C IV BALs at a rate of 2.3(-0.7)(+0.9) and 3.0(-0.8)(+1.0) per cent, respectively, and the frequency for BAL to non-BAL quasar transitions is 1.7(-0.6)(+0.8) per cent. We detect four re-emerging BALs over <= 3.88 rest-frame years on average and three re-disappearing BALs over <= 4.15 rest-frame years on average, the first reported cases of these types. We infer BAL lifetimes along the line of sight to be nominally less than or similar to 100-1000 yr using disappearing C IV BALs in our sample. Interpretations of (re-) emerging and (re-) disappearing BALs reveal evidence that collectively supports both transverse-motion and ionization-change scenarios to explain BAL variations. We constrain a nominal C IV/Si IV BAL-outflow location of less than or similar to 100 pc from the central source and a radial size of greater than or similar to 1x 10(-7) pc (0.02 au) using the ionization-change scenario, and constrain a nominal outflow location of less than or similar to 0.5 pc and a transverse size of similar to 0.01 pc using the transverse-motion scenario. Our findings are consistent with previous work, and provide evidence in support of BALs tracing compact flow geometries with small filling factors.", 
  "headline": "Broad absorption line disappearance and emergence using multiple-epoch spectroscopy from the Sloan Digital Sky Survey", 
  "identifier": 45141, 
  "image": "https://aperta.ulakbim.gov.tr/static/img/logo/aperta_logo_with_icon.svg", 
  "license": "http://www.opendefinition.org/licenses/cc-by", 
  "name": "Broad absorption line disappearance and emergence using multiple-epoch spectroscopy from the Sloan Digital Sky Survey", 
  "url": "https://aperta.ulakbim.gov.tr/record/45141"
}