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Title: A NEW METHOD FOR MEASURING EXTRAGALACTIC DISTANCES

We have pioneered a new method for the measurement of extragalactic distances. This method uses the time lag between variations in the short wavelength and long wavelength light from an active galactic nucleus (AGN), based on a quantitative physical model of dust reverberation that relates the time lag to the absolute luminosity of the AGN. We use the large homogeneous data set from intensive monitoring observations in optical and near-infrared wavelength bands with the dedicated 2 m MAGNUM telescope to obtain the distances to 17 AGNs in the redshift range z = 0.0024 to z = 0.0353. These distance measurements are compared with distances measured using Cepheid variable stars, and are used to infer that H {sub 0} = 73 ± 3 (random) km s{sup –1} Mpc{sup –1}. The systematic error in H {sub 0} is examined, and the uncertainty in the size distribution of dust grains is the largest source of the systematic error, which is much reduced for a sample of AGNs for which their parameter values in the model of dust reverberation are individually measured. This AGN time lag method can be used beyond 30 Mpc, the farthest distance reached by extragalactic Cepheids, and can be extended to high-redshift quasi-stellar objects.
Authors:
;  [1] ;  [2] ;  [3] ;  [4]
  1. Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)
  2. National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
  3. Center of Astro Engineering and Department of Electrical Engineering, Pontificia Univercsidad Catolica de Chile, Av. Vicuna Mackenna 4868 (Chile)
  4. Mount Stromlo Observatory, Research School of Astronomy and Astrophysics, Australian National University, Weston Creek P.O., ACT 2611 (Australia)
Publication Date:
OSTI Identifier:
22365961
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 784; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CEPHEIDS; COMPARATIVE EVALUATIONS; DISTANCE; ERRORS; GALAXIES; GALAXY NUCLEI; LUMINOSITY; NEAR INFRARED RADIATION; RANDOMNESS; RED SHIFT; TELESCOPES; VARIATIONS; VISIBLE RADIATION