Are there clouds in the BLR? Keck observations of NGC 4151

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We search for a direct signature of discrete ``clouds`` in the broad line region (BLR) of the Seyfert galaxy NGC 4151. For this purpose we apply cross correlation (CC) analysis to a high resolution KECK spectrum of the galaxy. No such signature is found in the data. In order for cloud models to be compatible with this result, there must be at least {approximately} 3 x 10{sup 7} emitting clouds in the BLR, where the limit is based on simulation of a homogeneous cloud population. More realistic distributions increase the lower limit to above 10{sup 8} . These numbers are ... continued below

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9 p.

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Arav, N. March 1998.

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We search for a direct signature of discrete ``clouds`` in the broad line region (BLR) of the Seyfert galaxy NGC 4151. For this purpose we apply cross correlation (CC) analysis to a high resolution KECK spectrum of the galaxy. No such signature is found in the data. In order for cloud models to be compatible with this result, there must be at least {approximately} 3 x 10{sup 7} emitting clouds in the BLR, where the limit is based on simulation of a homogeneous cloud population. More realistic distributions increase the lower limit to above 10{sup 8} . These numbers are an order of magnitude improvement on our previous limit from Mrk 335, where the improvement comes from higher S/N, broader lines, and refined simulations. Combined with the predicted upper limit for the number of emitting clouds in NGC 4151 (10{sup 6} - 10{sup 7}), the derived lower limit puts a strong constraint on the cloud scenario in the BLR of this object. Similar constraints can be placed on models where the emission originates in streams and sheets. Thus, this investigation suggests that the BELs in NGC 4151, and by extension in all AGNs, are not made of an ensemble of discrete independent emitters.

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9 p.

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OSTI as DE98058608

Other: FDE: PDF; PL:

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  • Structure and kinematics of quasar broad line regions, Lincoln, NE (United States), 22-26 Mar 1998

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  • Other: DE98058608
  • Report No.: UCRL-JC--130899
  • Report No.: CONF-9803110--
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 657449
  • Archival Resource Key: ark:/67531/metadc708914

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  • March 1998

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  • Sept. 12, 2015, 6:31 a.m.

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  • March 16, 2018, 10:57 a.m.

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Arav, N. Are there clouds in the BLR? Keck observations of NGC 4151, article, March 1998; California. (digital.library.unt.edu/ark:/67531/metadc708914/: accessed November 13, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.