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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  <dc:creator>McGraw, S. M.</dc:creator>
  <dc:creator>Brandt, W. N.</dc:creator>
  <dc:creator>Grier, C. J.</dc:creator>
  <dc:creator>Ak, N. Filiz</dc:creator>
  <dc:creator>Hall, P. B.</dc:creator>
  <dc:creator>Schneider, D. P.</dc:creator>
  <dc:creator>Anderson, S. F.</dc:creator>
  <dc:creator>Green, P. J.</dc:creator>
  <dc:creator>Hutchinson, T. A.</dc:creator>
  <dc:creator>Macleod, C. L.</dc:creator>
  <dc:creator>Vivek, M.</dc:creator>
  <dc:date>2017-01-01</dc:date>
  <dc:description>We investigate broad absorption line (BAL) disappearance and emergence using a 470 BAL-quasar sample over &lt;= 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 &lt;= 1.73-4.62 rest-frame years and 18 emerging BALs over &lt;= 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 &lt;= 3.88 rest-frame years on average and three re-disappearing BALs over &lt;= 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.</dc:description>
  <dc:identifier>https://aperta.ulakbim.gov.trrecord/45141</dc:identifier>
  <dc:identifier>oai:zenodo.org:45141</dc:identifier>
  <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:rights>http://www.opendefinition.org/licenses/cc-by</dc:rights>
  <dc:source>MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 469(3) 3163-3184</dc:source>
  <dc:title>Broad absorption line disappearance and emergence using multiple-epoch spectroscopy from the Sloan Digital Sky Survey</dc:title>
  <dc:type>info:eu-repo/semantics/article</dc:type>
  <dc:type>publication-article</dc:type>
</oai_dc:dc>