Big blue bump and transient active regions in seyfert galaxies

Sergei Nayakshin, Fulvio Melia

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


An important feature of the EUV spectrum (known as the Big Blue Bump, hereafter BBB) in Seyfert galaxies is the narrow range in its cutoff energy Ec from source to source, even though the luminosity changes by 4 orders of magnitude. Here we show that if the BBB is due to accretion disk emission, then in order to account for this "universality" in the value of Ec, the emission mechanism is probably optically thin bremsstrahlung. In addition, we demonstrate that the two-phase model with active regions localized on the surface of the cold disk is consistent with this constraint if the active regions are very compact and are highly transient, i.e., they evolve faster than one dynamical timescale.

Original languageEnglish (US)
Pages (from-to)L103-L106
JournalAstrophysical Journal
Issue number2 PART II
StatePublished - 1997


  • Accretion, accretion disks
  • Black hole physics
  • Galaxies: Seyfert
  • Magnetic fields
  • Plasmas
  • Radiative transfer

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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