Determination of the central mass in active galactic nuclei using cross-correlation lags and velocity dispersions

Michael J. Fromerth, Fulvio Melia

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

We here estimate the mass M of the central object in five active galactic nuclei (AGNs), using the most recent reverberation data obtained by the AGN Watch Consortium. The cross-correlation function (CCF) centroids of the broad Lyα γ1216 and C IV γ1549 lines are used to estimate the size of the broadline region (BLR) in these sources. We calculate the velocity dispersions of these lines in the root mean square (rms) spectra and then use our results to estimate M. We argue that our technique of calculating the velocity dispersion should work in the general case of an arbitrary line profile, unlike methods that depend on the measurement of the full-width at half-maximum (FWHM) of the broad line. We also show that our results agree with the FWHM method in the limit of a normal (Gaussian) line profile. The masses calculated here are considerably smaller than those calculated with the previous generation of reverberation data.

Original languageEnglish (US)
Pages (from-to)172-175
Number of pages4
JournalAstrophysical Journal
Volume533
Issue number1 PART 1
StatePublished - Apr 10 2000

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active galactic nuclei
cross correlation
time lag
reverberation
estimates
centroids
clocks
profiles
method

Keywords

  • Galaxies: active
  • Galaxies: nuclei
  • Galaxies: Seyfert
  • Line: profiles

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Determination of the central mass in active galactic nuclei using cross-correlation lags and velocity dispersions. / Fromerth, Michael J.; Melia, Fulvio.

In: Astrophysical Journal, Vol. 533, No. 1 PART 1, 10.04.2000, p. 172-175.

Research output: Contribution to journalArticle

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AB - We here estimate the mass M of the central object in five active galactic nuclei (AGNs), using the most recent reverberation data obtained by the AGN Watch Consortium. The cross-correlation function (CCF) centroids of the broad Lyα γ1216 and C IV γ1549 lines are used to estimate the size of the broadline region (BLR) in these sources. We calculate the velocity dispersions of these lines in the root mean square (rms) spectra and then use our results to estimate M. We argue that our technique of calculating the velocity dispersion should work in the general case of an arbitrary line profile, unlike methods that depend on the measurement of the full-width at half-maximum (FWHM) of the broad line. We also show that our results agree with the FWHM method in the limit of a normal (Gaussian) line profile. The masses calculated here are considerably smaller than those calculated with the previous generation of reverberation data.

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