We present a Chandra image of the quasar, jet, and lobes of PKS 1354+195 (=4C 19.44). The radio jet is 18 arcsec long, and appears to be very
straight. The length gives many independent spatial resolution elements in the Chandra image while the straightness implies that the geometrical factors are constant along the jet although their values are uncertain.
We also have 4 frequency radio images with half to one arcsecond angular resolution, and use HST and Spitzer data to study
the broad band spectral energy distributions. The X-ray and radio spectra are both consistent with a spectrum f
−0.7 for the integrated jet. Using that spectral index, the model of inverse Compton scattering of electrons on the cosmic microwave
background (IC/CMB) gives magnetic field strengths and Doppler factors that are relatively constant along the jet. Extended
X-ray emission is evident in the direction of the otherwise unseen counter-jet. X-ray emission continues past the radio jet
to the South, and is detected within both the southern and northern radio lobes.
[Show abstract][Hide abstract] ABSTRACT: X-ray jets in AGNs are commonly observed in FR II and FR I radio galaxies, but rarely in BL Lac objects, most probably due to their orientation close to the line of sight and the ensuing foreshortening effects. Only three BL Lac objects are known so far to contain a kpc-scale X-ray jet. In this paper we present the evidence for the existence of a fourth extended X-ray jet in the classical radio-selected source S5 2007+777, which for its hybrid FR I and FR II radio morphology has been classified as a HYMOR (HYbrid MOrphology Radio source). Our Chandra ACIS-S observations of this source revealed an X-ray counterpart to the 19" long radio jet. Interestingly, the X-ray properties of the kpc-scale jet in S5 2007+777 are very similar to those observed in FR II jets. First, the X-ray morphology closely mirrors the radio one, with the X-rays being concentrated in the discrete radio knots. Second, the X-ray continuum of the jet/brightest knot is described by a very hard power law, with photon index GammaX~1, although the uncertainties are large. Third, the optical upper limit from archival HST data implies a concave radio-to-X-ray SED. If the X-ray emission is attributed to IC/CMB with equipartition, strong beaming (delta=13) is required, implying a very large scale (Mpc) jet. The beaming requirement can be somewhat relaxed assuming a magnetic field lower than equipartition. Alternatively, synchrotron emission from a second population of very high-energy electrons is viable. Comparison to other HYMOR jets detected with Chandra is discussed, as well as general implications for the origin of the FR I/FR II division.
The Astrophysical Journal 09/2008; 684(2):862-869. DOI:10.1086/589918 · 5.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Jet physics is again flourishing as a result of Chandra's ability to resolve high-energy emission from the radio-emitting structures of active galaxies and separate it from the X-ray-emitting thermal environments of the jets. These enhanced capabilities have coincided with an increasing interest in the link between the growth of super-massive black holes and galaxies, and an appreciation of the likely importance of jets in feedback processes. I review the progress that has been made using Chandra and XMM-Newton observations of jets and the medium in which they propagate, addressing several important questions, including: Are the radio structures in a state of minimum energy? Do powerful large-scale jets have fast spinal speeds? What keeps jets collimated? Where and how does particle acceleration occur? What is jet plasma made of? What does X-ray emission tell us about the dynamics and energetics of radio plasma/gas interactions? Is a jet's fate determined by the central engine? Comment: 46 pages. Accepted for publication in The Astronomy and Astrophysics Review
[Show abstract][Hide abstract] ABSTRACT: We present results from continued Chandra X-ray imaging and spectroscopy of a
flux-limited sample of flat spectrum radio-emitting quasars with jet-like
extended structure. X-rays are detected from 24 of the 39 jets observed so far.
We compute the distribution of alpha_rx, the spectral index between the X-ray
and radio bands, showing that it is broad, extending at least from 0.8 to 1.2.
While there is a general trend that the radio brightest jets are detected most
often, it is clear that predicting the X-ray flux from the radio knot flux
densities is risky so a shallow X-ray survey is the most effective means for
finding jets that are X-ray bright. We test the model in which the X-rays
result from inverse Compton (IC) scattering of cosmic microwave background
(CMB) photons by relativistic electrons in the jet moving with high bulk
Lorentz factor nearly along the line of sight. Depending on how the jet
magnetic fields vary with z, the observed X-ray to radio flux ratios do not
follow the redshift dependence expected from the IC-CMB model. For a subset of
our sample with known superluminal motion based on VLBI observations, we
estimate the angle of the kpc-scale jet to the line of sight by considering the
additional information in the bends observed between pc- and kpc-scale jets.
These angles are sometimes much smaller than estimates based on the IC-CMB
model with a Lorentz factor of 15, indicating that these jets may decelerate
significantly from pc scales to kpc scales.
The Astrophysical Journal Supplement Series 01/2011; 193(1). DOI:10.1088/0067-0049/193/1/15 · 11.22 Impact Factor
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