Probing the physics of narrow-line regions in active galaxies. III. accretion and cocoon shocks in the liner NGC 1052

Michael A. Dopita, I. Ting Ho, Linda L. Dressel, Ralph Sutherland, Lisa Kewley, Rebecca Davies, Elise Hampton, Prajval Shastri, Preeti Kharb, Jessy Jose, Harish Bhatt, S. Ramya, Julia Scharwächter, Chichuan Jin, Julie Banfield, Ingyin Zaw, Bethan James, Stéphanie Juneau, Shweta Srivastava

Research output: Contribution to journalArticlepeer-review


We present Wide Field Spectrograph integral field spectroscopy and Hubble Space Telescope Faint Object Spectrograph spectroscopy for the low-ionization nuclear emission line region (LINER) galaxy NGC 1052. We infer the presence of a turbulent accretion flow forming a small-scale accretion disk. We find a large-scale outflow and ionization cone along the minor axis of the galaxy. Part of this outflow region is photoionized by the active galactic nucleusand shares properties with the extended narrow-line region of Seyfert galaxies, but the inner (″) accretion disk and the region around the radio jet appear shock excited. The emission-line properties can be modeled by a "double-shock" model in which the accretion flow first passes through an accretion shock in the presence of a hard X-ray radiation, and the accretion disk is then processed through a cocoon shock driven by the overpressure of the radio jets. This model explains the observation of two distinct densities (∼104 and ∼106 cm-3)and provides a good fit to the observed emission-line spectrum. We derive estimates for the velocities of the two shock components and their mixing fractions, the black hole mass, and the accretion rate needed to sustain the LINER emission and derive an estimate for the jet power. Our emission-line model is remarkably robust against variation of input parametersand hence offers a generic explanation for the excitation of LINER galaxies, including those of spiral type such as NGC 3031 (M81).

Original languageEnglish (US)
Article number42
JournalAstrophysical Journal
Issue number1
StatePublished - Mar 1 2015


  • black hole physics
  • galaxies: individual (NGC 1052, M81)
  • galaxies: jets
  • galaxies: nuclei
  • shock waves

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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