Superluminous Transients at AGN Centers from Interaction between Black Hole Disk Winds and Broad-line Region Clouds

Takashi J. Moriya, Masaomi Tanaka, Tomoki Morokuma, Ken Ohsuga

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We propose that superluminous transients that appear at central regions of active galactic nuclei (AGNs) such as CSS100217:102913+404220 (CSS100217) and PS16dtm, which reach near- or super-Eddington luminosities of the central black holes, are powered by the interaction between accretion-disk winds and clouds in broad-line regions (BLRs) surrounding them. If the disk luminosity temporarily increases by, e.g., limit-cycle oscillations, leading to a powerful radiatively driven wind, strong shock waves propagate in the BLR. Because the dense clouds in the AGN BLRs typically have similar densities to those found in SNe IIn, strong radiative shocks emerge and efficiently convert the ejecta kinetic energy to radiation. As a result, transients similar to SNe IIn can be observed at AGN central regions. Since a typical black hole disk-wind velocity is ≃0.1c, where c is the speed of light, the ejecta kinetic energy is expected to be ≃1052 erg when ≃1 M o is ejected. This kinetic energy is transformed to radiation energy in a timescale for the wind to sweep up a similar mass to itself in the BLR, which is a few hundred days. Therefore, both luminosities (∼1044 erg s-1) and timescales (∼100 days) of the superluminous transients from AGN central regions match those expected in our interaction model. If CSS100217 and PS16dtm are related to the AGN activities triggered by limit-cycle oscillations, they become bright again in coming years or decades.

Original languageEnglish
Article numberL19
JournalAstrophysical Journal Letters
Volume843
Issue number2
DOIs
Publication statusPublished - 2017 Jul 10
Externally publishedYes

Keywords

  • ISM: jets and outflows
  • accretion, accretion disks
  • galaxies: active
  • galaxies: nuclei

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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