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.

Citation Style Language JSON

{
  "DOI": "10.1093/mnras/stx1063", 
  "abstract": "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.", 
  "author": [
    {
      "family": "McGraw", 
      "given": " S. M."
    }, 
    {
      "family": "Brandt", 
      "given": " W. N."
    }, 
    {
      "family": "Grier", 
      "given": " C. J."
    }, 
    {
      "family": "Ak", 
      "given": " N. Filiz"
    }, 
    {
      "family": "Hall", 
      "given": " P. B."
    }, 
    {
      "family": "Schneider", 
      "given": " D. P."
    }, 
    {
      "family": "Anderson", 
      "given": " S. F."
    }, 
    {
      "family": "Green", 
      "given": " P. J."
    }, 
    {
      "family": "Hutchinson", 
      "given": " T. A."
    }, 
    {
      "family": "Macleod", 
      "given": " C. L."
    }, 
    {
      "family": "Vivek", 
      "given": " M."
    }
  ], 
  "container_title": "MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY", 
  "id": "45141", 
  "issue": "3", 
  "issued": {
    "date-parts": [
      [
        2017, 
        1, 
        1
      ]
    ]
  }, 
  "page": "3163-3184", 
  "title": "Broad absorption line disappearance and emergence using multiple-epoch spectroscopy from the Sloan Digital Sky Survey", 
  "type": "article-journal", 
  "volume": "469"
}