Changing look: from Compton-thick to Compton-thin, or the rebirth of fossil active galactic nuclei

2003/02/17 by G. Matt, M. Guainazzi, R. Maiolino · 8 citations
Physics and Astronomy · #Absorption (acoustics) #Active galactic nucleus #Advanced X-ray Imaging Techniques #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Compton scattering #Galaxies: Formation, Evolution, Phenomena #Galaxy #Optics #Photon #Physics #Radiation #Reflection (computer programming) #Spectral line #astro-ph

paper · pdf · doi:10.1046/j.1365-8711.2003.06539.x

published as Mon.Not.Roy.Astron.Soc. 342 (2003) 422 · accepted for publication in MNRAS

arxiv created 2003/02/17 · openalex publication_date 2003/06/12 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We discuss the properties of a small sample of type 2 Seyfert galaxies whose X-ray spectra changed appearance on time-scales of years, becoming reflection-dominated from Compton-thin, or vice versa. A reflection-dominated spectrum is usually taken as evidence of Compton-thick absorption, but we instead argue that such a spectrum is due to a temporary switching-off of the nuclear radiation. The observations discussed here may help to explain mismatches between optical and X-ray classifications, and provide new strong and direct evidence for the presence of more than one cold circumnuclear region in type 2 Seyfert galaxies.

Citations

• The formerly X-ray reflection-dominated Seyfert 2 galaxy NGC 6300
• AnRXTEObservation of NGC 6300: a New Bright Compton Reflection–dominated Seyfert 2 Galaxy

Cited by

• A self-consistent approach to the hard and soft states of 4U 1705-44
• The nature of the hard state of Cygnus X-3
• Suzakuobservation of the Phoenix galaxy
• THE DISCOVERY OF THE FIRST “CHANGING LOOK” QUASAR: NEW INSIGHTS INTO THE PHYSICS AND PHENOMENOLOGY OF ACTIVE GALACTIC NUCLEI
• The High‐Energy Spectrum of NGC 4151
• The detection and X-ray view of the changing look AGN HE 1136-2304
• Luminosity-dependent unification of active galactic nuclei and the X-ray Baldwin effect
• The high energy emission line spectrum of NGC 1068
• 2MASX J00423991 + 3017515: an offset active galactic nucleus in an interacting system