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

Journal Article · Sat Oct 20 00:00:00 EDT 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/758/2/L27· OSTI ID:22078492

Godfrey, L E. H.; Ekers, R ^[1]; Lovell, J E. J. ^[2]; Burke-Spolaor, S ^[3]; Bicknell, G V; Jauncey, D L ^[4]; Birkinshaw, M; Worrall, D M; Schwartz, D A ^[5]; Marshall, H L ^[6]; Gelbord, J ^[7]; Perlman, E S ^[8]; Georganopoulos, M ^[9]

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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)

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.

• OSTI ID: 22078492
• Journal Information: Astrophysical Journal Letters, Vol. 758, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

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