2004/05/25 by Svetlana Jorstad, S. G. Jorstad, Alan P. Marscher +1 · 4 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.1086/423800
published as Astrophys.J. 614 (2004) 615-625 · 28 pages with 9 figures. Revised version corrects eq. A1 & A4 (which incorrectly divided by 4pi) and entries in tables. Minor changes are made in the text. submitted to ApJ
arxiv created 2004/05/25 · openalex publication_date 2004/10/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We present Chandra X-ray (0.2-8 keV) and Very Large Array radio (15 and 5 GHz) images of the γ-ray-bright, superluminal quasar 0827+243. The X-ray jet bends sharply—by ~90°, presumably amplified by projection effects—5'' from the core. Only extremely weak radio emission is detected between the nuclear region and the bend. The X-ray continuum spectrum of the combined emission of the knots is rather flat, with a slope of -0.4 ± 0.2, while the 5-15 GHz spectra are steeper for knots detected in the radio. These characteristics, as well as nondetection of the jet in the optical band by the Hubble Space Telescope , pose challenges to models for the spectral energy distributions (SEDs) of the jet features. The SEDs could arise from pure synchrotron emission from either a single or dual population of relativistic electrons only if the minimum electron energy per unit mass γ min ≳ 1000. In the case of a single population, the radiative energy losses of the X-ray-emitting electrons must be suppressed owing to inverse Compton scattering in the Klein-Nishina regime, as proposed by Dermer & Atoyan. Alternatively, the X-ray emission could result from inverse Compton scattering of the cosmic microwave background photons by electrons with Lorentz factors as low as γ ~ 15. In all models, the bulk Lorentz factor of the jet flow Γ ≳ 20 found on parsec scales must continue without substantial deceleration out to 800 kpc (deprojected) from the nucleus, and the magnetic field is very low, ≲2 μG, until the bend. Deceleration does appear to occur at and beyond the sharp bend, such that the flow could be only mildly relativistic at the end of the jet. Significant intensification of the magnetic field occurs downstream of the bend, where there is an offset between the projected positions of the X-ray and radio features.