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Title: PERIODIC STRUCTURE IN THE MEGAPARSEC-SCALE JET OF PKS 0637-752

Abstract

We present 18 GHz Australia Telescope Compact Array imaging of the megaparsec-scale quasar jet PKS 0637-752 with angular resolution {approx}0.''58. We draw attention to a spectacular train of quasi-periodic knots along the inner 11'' of the jet, with average separation {approx}1.1 arcsec (7.6 kpc projected). We consider two classes of model to explain the periodic knots: those that involve a static pattern through which the jet plasma travels (e.g., stationary shocks) and those that involve modulation of the jet engine. Interpreting the knots as re-confinement shocks implies the jet kinetic power Q{sub jet} {approx} 10{sup 46} erg s{sup -1}, but the constant knot separation along the jet is not expected in a realistic external density profile. For models involving modulation of the jet engine, we find that the required modulation period is 2 Multiplication-Sign 10{sup 3} yr < {tau} < 3 Multiplication-Sign 10{sup 5} yr. The lower end of this range is applicable if the jet remains highly relativistic on kiloparsec scales, as implied by the IC/CMB model of jet X-ray emission. We suggest that the periodic jet structure in PKS 0637-752 may be analogous to the quasi-periodic jet modulation seen in the microquasar GRS 1915+105, believed to result frommore » limit cycle behavior in an unstable accretion disk. If variations in the accretion rate are driven by a binary black hole, the predicted orbital radius is 0.7 pc {approx}< a {approx}< 30 pc, which corresponds to a maximum angular separation of {approx}0.1-5 mas.« less

Authors:
;  [1];  [2];  [3]; ;  [4]; ; ;  [5];  [6];  [7];  [8];  [9]
  1. International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6102 (Australia)
  2. CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 2121 (Australia)
  3. NASA Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
  4. Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston, ACT 2611 (Australia)
  5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  6. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  7. Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom)
  8. Physics and Space Sciences Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States)
  9. Department of Physics, Joint Center for Astrophysics, University of Maryland-Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)
Publication Date:
OSTI Identifier:
22078492
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 758; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BLACK HOLES; CONFINEMENT; DENSITY; GHZ RANGE; LIMIT CYCLE; MODULATION; PERIODICITY; PHOTON EMISSION; PLASMA; QUASARS; RELATIVISTIC RANGE; SPATIAL RESOLUTION; TELESCOPES; X RADIATION

Citation Formats

Godfrey, L. E. H., Ekers, R., Lovell, J. E. J., Burke-Spolaor, S., Bicknell, G. V., Jauncey, D. L., Birkinshaw, M., Worrall, D. M., Schwartz, D. A., Marshall, H. L., Gelbord, J., Perlman, E. S., and Georganopoulos, M., E-mail: L.Godfrey@curtin.edu.au. PERIODIC STRUCTURE IN THE MEGAPARSEC-SCALE JET OF PKS 0637-752. United States: N. p., 2012. Web. doi:10.1088/2041-8205/758/2/L27.
Godfrey, L. E. H., Ekers, R., Lovell, J. E. J., Burke-Spolaor, S., Bicknell, G. V., Jauncey, D. L., Birkinshaw, M., Worrall, D. M., Schwartz, D. A., Marshall, H. L., Gelbord, J., Perlman, E. S., & Georganopoulos, M., E-mail: L.Godfrey@curtin.edu.au. PERIODIC STRUCTURE IN THE MEGAPARSEC-SCALE JET OF PKS 0637-752. United States. doi:10.1088/2041-8205/758/2/L27.
Godfrey, L. E. H., Ekers, R., Lovell, J. E. J., Burke-Spolaor, S., Bicknell, G. V., Jauncey, D. L., Birkinshaw, M., Worrall, D. M., Schwartz, D. A., Marshall, H. L., Gelbord, J., Perlman, E. S., and Georganopoulos, M., E-mail: L.Godfrey@curtin.edu.au. Sat . "PERIODIC STRUCTURE IN THE MEGAPARSEC-SCALE JET OF PKS 0637-752". United States. doi:10.1088/2041-8205/758/2/L27.
@article{osti_22078492,
title = {PERIODIC STRUCTURE IN THE MEGAPARSEC-SCALE JET OF PKS 0637-752},
author = {Godfrey, L. E. H. and Ekers, R. and Lovell, J. E. J. and Burke-Spolaor, S. and Bicknell, G. V. and Jauncey, D. L. and Birkinshaw, M. and Worrall, D. M. and Schwartz, D. A. and Marshall, H. L. and Gelbord, J. and Perlman, E. S. and Georganopoulos, M., E-mail: L.Godfrey@curtin.edu.au},
abstractNote = {We present 18 GHz Australia Telescope Compact Array imaging of the megaparsec-scale quasar jet PKS 0637-752 with angular resolution {approx}0.''58. We draw attention to a spectacular train of quasi-periodic knots along the inner 11'' of the jet, with average separation {approx}1.1 arcsec (7.6 kpc projected). We consider two classes of model to explain the periodic knots: those that involve a static pattern through which the jet plasma travels (e.g., stationary shocks) and those that involve modulation of the jet engine. Interpreting the knots as re-confinement shocks implies the jet kinetic power Q{sub jet} {approx} 10{sup 46} erg s{sup -1}, but the constant knot separation along the jet is not expected in a realistic external density profile. For models involving modulation of the jet engine, we find that the required modulation period is 2 Multiplication-Sign 10{sup 3} yr < {tau} < 3 Multiplication-Sign 10{sup 5} yr. The lower end of this range is applicable if the jet remains highly relativistic on kiloparsec scales, as implied by the IC/CMB model of jet X-ray emission. We suggest that the periodic jet structure in PKS 0637-752 may be analogous to the quasi-periodic jet modulation seen in the microquasar GRS 1915+105, believed to result from limit cycle behavior in an unstable accretion disk. If variations in the accretion rate are driven by a binary black hole, the predicted orbital radius is 0.7 pc {approx}< a {approx}< 30 pc, which corresponds to a maximum angular separation of {approx}0.1-5 mas.},
doi = {10.1088/2041-8205/758/2/L27},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 758,
place = {United States},
year = {2012},
month = {10}
}