Non-LTE, relativistic accretion disk fits to 3C 273 and the origin of the Lyman limit spectral break

Omer Blaes, Ivan Hubeny, Eric Agol, Julian H. Krolik

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


We fit general relativistic, geometrically thin accretion disk models with non-LTE atmospheres to near-simultaneous multiwavelength data of 3C 273, extending from the optical to the far-ultraviolet. Our model fits show no flux discontinuity associated with a hydrogen Lyman edge, but they do exhibit a spectral break which qualitatively resembles that seen in the data. This break arises from relativistic smearing of Lyman emission edges which are produced locally at tens of gravitational radii in the disk. We discuss the possible effects of metal line blanketing on the model spectra, as well as the substantial Comptonization required to explain the observed soft X-ray excess. Our best-fit accretion disk model underpredicts the near-ultraviolet emission in this source and also has an optical spectrum which is too red. We discuss some of the remaining physical uncertainties and suggest in particular that an extension of our models to the slim disk regime and/or including nonzero magnetic torques across the innermost stable circular orbit may help resolve these discrepancies.

Original languageEnglish (US)
Pages (from-to)560-568
Number of pages9
JournalAstrophysical Journal
Issue number2 PART 1
StatePublished - Dec 20 2001


  • Accretion, accretion disks
  • Galaxies: active
  • Quasars: individual (3C 273)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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