THE MEGAPARSEC-SCALE X-RAY JET OF THE BL Lac OBJECT OJ287

We present an X-ray image of the BL Lacertae (BL Lac) object OJ287 revealing a long jet, curved by 55° and extending 20″ or 90 kpc from the nucleus. This de-projects to >1 Mpc based on the viewing angle on parsec scales. Radio emission follows the general X-ray morphology but extends even farther from the nucleus. The upper limit to the isotropic radio luminosity, ∼2 × 1024 W Hz−1, places the source in the Fanaroff–Riley 1 (FR 1) class, as expected for BL Lac objects. The spectral energy distribution indicates that the extended X-ray emission is from inverse Compton scattering of cosmic microwave background photons. In this case, the derived magnetic field is B ≈ 5 μG, the minimum electron energy is 7–40mec2, and the Doppler factor is δ ≈ 8 in a knot 8″ from the nucleus. The minimum total kinetic power of the jet is (1–2)×1045 erg s−1. Upstream of the bend, the width of the X-ray emission in the jet is about half the projected distance from the nucleus. This implies that the highly relativistic bulk motion is not limited to an extremely thin spine, as has been proposed previously for FR 1 sources. The bending of the jet, the deceleration of the flow from parsec to kiloparsec scales, and the knotty structure can all be caused by standing shocks inclined by ∼7° to the jet axis. Moving shocks resulting from major changes in the flow properties can also reproduce the knotty structure, but such a model does not explain as many of the observational details.

[1]  J. Lovell,et al.  A MULTI-WAVELENGTH STUDY OF THE JET, LOBES, AND CORE OF THE QUASAR PKS 2101−490 , 2012, 1208.0069.

[2]  Paul S. Smith,et al.  LOCATION OF γ-RAY FLARE EMISSION IN THE JET OF THE BL LACERTAE OBJECT OJ287 MORE THAN 14 pc FROM THE CENTRAL ENGINE , 2010, 1011.6454.

[3]  M. Pohl,et al.  MAGNETIC-FIELD AMPLIFICATION BY TURBULENCE IN A RELATIVISTIC SHOCK PROPAGATING THROUGH AN INHOMOGENEOUS MEDIUM , 2010, 1011.2171.

[4]  R. Sambruna,et al.  A Kiloparsec-Scale X-Ray Jet in the BL Lac Source S5 2007+777 , 2008 .

[5]  M. Kidger,et al.  A massive binary black-hole system in OJ 287 and a test of general relativity , 2008, Nature.

[6]  T. Krichbaum,et al.  Search for Electron-Positron Annihilation Radiation from the Jet in 3C 120 , 2007 .

[7]  C. Urry,et al.  Deep Chandra and Multicolor HST Observations of the Jets of 3C 371 and PKS 2201+044 , 2007, 0707.3980.

[8]  D. Harris,et al.  X-Ray Emission from Extragalactic Jets , 2006, astro-ph/0607228.

[9]  C. Urry,et al.  Shedding New Light on the 3C 273 Jet with the Spitzer Space Telescope , 2006, astro-ph/0605530.

[10]  D. Harris,et al.  New Chandra Observations of the Jet in 3C 273. I. Softer X-Ray than Radio Spectra and the X-Ray Emission Mechanism , 2006, astro-ph/0605529.

[11]  J. McKinney.  General relativistic force-free electrodynamics: a new code and applications to black hole magnetospheres , 2006, astro-ph/0601410.

[12]  Paul S. Smith,et al.  Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Jet Kinematics from Bimonthly Monitoring with the Very Long Baseline Array , 2005, astro-ph/0502501.

[13]  J. Kataoka,et al.  X-Ray Emission Properties of Large-Scale Jets, Hot Spots, and Lobes in Active Galactic Nuclei , 2004, astro-ph/0411042.

[14]  K. Kingham,et al.  Structure of OJ 287 from Geodetic VLBA Data , 2004 .

[15]  I. McHardy,et al.  Synchrotron Self-Compton Model for Rapid Nonthermal Flares in Blazars with Frequency-dependent Time Lags , 2004, astro-ph/0406235.

[16]  The Highly Relativistic Kiloparsec-Scale Jet of the Gamma-Ray Quasar 0827+243 , 2004, astro-ph/0405424.

[17]  C. Dermer,et al.  Nonthermal Radiation Processes in X-Ray Jets , 2004, astro-ph/0404139.

[18]  M. Sikora,et al.  On Multiwavelength Emission of Large-Scale Quasar Jets , 2004, astro-ph/0401356.

[19]  D. Meier.  The theory and simulation of relativistic jet formation: towards a unified model for micro- and macroquasars , 2003, astro-ph/0312048.

[20]  A. Meli,et al.  Particle acceleration in ultra-relativistic oblique shock waves , 2002, astro-ph/0212329.

[21]  C. Dermer,et al.  X-Ray Synchrotron Spectral Hardenings from Compton and Synchrotron Losses in Extended Chandra Jets , 2002, astro-ph/0202406.

[22]  M. Birkinshaw,et al.  Chandra finds that X-ray jets are common in low-power radio galaxies , 2001, astro-ph/0106246.

[23]  A. V. Yurchenko,et al.  Multiepoch Very Long Baseline Array Observations of EGRET-detected Quasars and BL Lacertae Objects: Superluminal Motion of Gamma-Ray Bright Blazars , 2001, astro-ph/0101570.

[24]  G. Ghisellini,et al.  Large-scale jets in active galactic nuclei: multiwavelength mapping , 2000, astro-ph/0008021.

[25]  C. Urry,et al.  The X-Ray Jet of PKS 0637–752: Inverse Compton Radiation from the Cosmic Microwave Background? , 2000, astro-ph/0007441.

[26]  R. Laing,et al.  Asymmetries in the jets of weak radio galaxies , 1999 .

[27]  A. Marscher,et al.  Hydrodynamical Models of Superluminal Sources , 1997 .

[28]  M. Lister,et al.  Statistical Effects of Doppler Beaming and Malmquist Bias on Flux-limited Samples of Compact Radio Sources , 1997 .

[29]  B. Punsly.  Spectral Diagnostics of Blazar Central Engines. II. Hydromagnetic Theory , 1996 .

[30]  D. Ellison,et al.  Nonlinear Particle Acceleration in Oblique Shocks , 1996, astro-ph/9609182.

[31]  E. Perlman,et al.  New very large array maps of highly core-dominated BL Lacs: Testing unified schemes , 1994 .

[32]  G. Bicknell.  On the Relationship between BL Lacertae Objects and Fanaroff-Riley I Radio Galaxies , 1993, astro-ph/9308033.

[33]  W. K. Cobb,et al.  Linear polarization of radiation from oblique and conical shocks , 1990 .

[34]  J. Dickey,et al.  H I in the Galaxy , 1990 .

[35]  R. Blandford,et al.  Semidynamical models of radio jets: relativistic beaming and source counts. , 1985 .

[36]  R. Antonucci,et al.  Extended radio emission and the nature of blazars , 1985 .

[37]  A. Königl.  Relativistic gasdynamics in two dimensions , 1980 .

[38]  J. Riley,et al.  The Morphology of Extragalactic Radio Sources of High and Low Luminosity , 1974 .

[39]  M. Lighthill.  Supersonic Flow and Shock Waves , 1949, Nature.

[40]  Richard Courant,et al.  Supersonic Flow And Shock Waves , 1948 .