skip to main content

Title: EVIDENCE FOR A RECEDING DUST SUBLIMATION REGION AROUND A SUPERMASSIVE BLACK HOLE

The near-IR emission in Type 1 active galactic nuclei (AGNs) is thought to be dominated by the thermal radiation from dust grains that are heated by the central engine in the UV/optical and are almost at the sublimation temperature. A brightening of the central source can thus further sublimate the innermost dust, leading to an increase in the radius of the near-IR emitting region. Such changes in radius have been indirectly probed by the measurements of the changes in the time lag between the near-IR and UV/optical light variation. Here we report direct evidence for such a receding sublimation region through the near-IR interferometry of the brightest Type 1 AGN in NGC 4151. The increase in radius follows a significant brightening of the central engine with a delay of at least a few years, which is thus the implied destruction timescale of the innermost dust distribution. Compiling historic flux variations and radius measurements, we also infer the reformation timescale for the inner dust distribution to be several years in this galactic nucleus. More specifically and quantitatively, we find that the radius at a given time seems to be correlated with a long-term average of the flux over the previous severalmore » (∼6) years, instead of the instantaneous flux. Finally, we also report measurements of three more Type 1 AGNs newly observed with the Keck interferometer, as well as the second epoch measurements for three other AGNs.« less
Authors:
; ;  [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
  2. Physics Department, University of California, Santa Barbara, CA 93106 (United States)
  3. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
  4. National Science Foundation, 4301 Wilson Boulevard, Arlington, VA 22230 (United States)
  5. Observatoire de la Côte d Azur, Departement FIZEAU, Boulevard de l'Observatoire, BP 4229, F-06304 Nice Cedex 4 (France)
  6. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
Publication Date:
OSTI Identifier:
22215446
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 775; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; COSMIC DUST; DISTRIBUTION; GALAXIES; GALAXY NUCLEI; INTERFEROMETERS; SUBLIMATION; THERMAL RADIATION; VARIATIONS; VISIBLE RADIATION