[ITAL]Chandra[/ITAL] Discovery of a 100 kiloparsec X-Ray Jet in PKS 0637−752

Schwartz, D. A.; Marshall, Herman L.; Lovell, J. E. J.; Piner, B. G.; Tingay, S. J.; Birkinshaw, Mark; Chartas, G.; Elvis, M.; Feigelson, E. D.; Ghosh, K. K.; Harris, D. E.; Hirabayashi, H.; Hooper, E. J.; Jauncey, D. L.; Lanzetta, Kenneth M.; Mathur, S.; Preston, R. A.; Tucker, W.; Virani, S.; Wilkes, B. J.; Worrall, D. M.

doi:10.1086/312875

Cited by 186 publications

(147 citation statements)

References 18 publications

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“…Very small angles to the line of sight are not required, and the total jet power required is considerably less , as the electron energy distribution need not be extended to very low values. The main objection to a second synchrotron component heretofore has simply been its unexplained nature; Schwartz et al (2000) notes that there is no reason why a second population of high-energy electrons should be co-spatial with the first. However, this co-occurrence of two very different electron populations, if the correct interpretation, is obviously a very important clue to the particle acceleration mechanism in large-scale jets, of which we still know little.…”

Section: Discussionmentioning

confidence: 99%

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Ruling Out Ic/CMB X-Rays in PKS 0637-752 and the Implications for Tev Emission From Large-Scale Quasar Jets

Meyer

Georganopoulos

Sparks

et al. 2015

ApJ

130

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The Chandra X-ray observatory has discovered dozens of resolved, kiloparsec-scale jets associated with powerful quasars in which the X-ray fluxes are observed to be much higher than the expected level based on the radio-optical synchrotron spectrum. The most popular explanation for the anomalously high and hard X-ray fluxes is that these jets do not decelerate significantly by the kiloparsec scale, but rather remain highly relativistic (Lorentz factors Γ ∼ 10). By adopting a small angle to the line of sight, the X-rays can thus be explained by inverse Compton upscattering of cosmic microwave background (CMB) photons (IC/CMB), where the observed emission is strongly Doppler boosted. Using over six years of Fermi monitoring data, we show that the expected hard, steady gamma-ray emission implied by the IC/CMB model is not seen in PKS 0637-752, the prototype jet for which this model was first proposed. IC/CMB emission is thus ruled out as the source of the X-rays, joining recent results for the jets in 3C 273 (using the same method) and PKS 1136-135 (using UV polarization). We further show that the Fermi observations give an upper limit of δ < 6.5 for the four brightest X-ray knots of PKS 0637-752, and derive an updated limit of δ < 7.8 for knots A and B1 of 3C 273 (assuming equipartition). Finally, we discuss the fact that high levels of synchrotron X-ray emission in a slow jet will unavoidably lead to a level of angle-integrated TeV emission which exceeds that of the TeV BL Lac class.

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Section: Discussionmentioning

confidence: 99%

“…In 1999 August, the Chandra X-ray Observatory observed its first celestial target, quasar PKS 0637-752, during the initial focusing of the telescope (Chartas et al 2000;Schwartz et al 2000). Along with the bright quasar core, Chandra unexpectedly detected X-rays from the kiloparsec (kpc) scale relativistic jet (previously known from radio imaging, Figure 1).…”

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confidence: 96%

Ruling Out Ic/CMB X-Rays in PKS 0637-752 and the Implications for Tev Emission From Large-Scale Quasar Jets

Meyer

Georganopoulos

Sparks

et al. 2015

ApJ

130

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“…However, more powerful FR II (quasar) jets have very different spectral energy distributions (SEDs), with the observed X-rays being harder and at a higher flux than expected from extrapolating the radio-to-optical synchrotron spectrum, suggesting that they are part of a separate spectral component (Figure 1b). A synchrotron self-Compton (SSC) nature for the X-rays was disfavored [9,10], as the X-rays are at least a factor of 100 higher than the anticipated SSC flux (e.g., [9][10][11][12][13]). A controversy with serious implications for jet physics emerged over the nature of the X-rays.…”

Section: Introductionmentioning

confidence: 99%

Recent Progress in Understanding the Large Scale Jets of Powerful Quasars

2016

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Our understanding of the physics of kpc-scale quasar jets had seemed to converge to a paradigm in which these jets are as highly relativistic on the kpc scale as they are on sub-pc scales close to the central black hole. Retaining bulk Lorentz factors (Γ) on the order of 10-20 at these distances implies a jet power comparable to or higher than their Eddington luminosity. We recently started challenging this paradigm, which was put in place to explain the surprisingly bright X-ray emission of the knots of many quasar jets as inverse Compton scattering off the cosmic microwave background (IC/CMB). We have shown that the knot X-ray emission of the archetypical jets 3C 273 and PKS 0637-752 is not due to IC/CMB. With IC/CMB disfavored, an alternative interpretation for the X-rays is synchrotron radiation from a second population of electrons accelerated in situ up to ∼100 TeV. These results are the first step towards resolving the long-standing issue of the nature of the X-ray emission in powerful quasar jets. Comprehensive observational and theoretical work on essentially all X-ray-detected large-scale quasar jets to test the IC/CMB model over a much larger population needs to be done to examine the implications of slower jets that are extremely efficient accelerators. A fascinating case can be made that-contrary to popular belief-the total radiative power of the large-scale jet of these sources is comparable to that of the quasar core. Even more so, the angle-integrated TeV output of these (previously thought TeV-quiet) quasar jets likely makes them the dominant class among active galactic nuclei (AGN), exceeding the TeV production of so-called TeV blazars.

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“…Indeed, closeness to the equipartition value is sometimes used as a validation criterion for a magnetic field estimated by any other means. That seems unacceptable, since there is no convincing theoretical argument for equipartition between radio-emitting electrons and magnetic fields, and empirical evidence argues that not all sources are in equipartition (e.g., Centaurus B, Tashiro et al 1998; PKS 0637À752, Schwartz et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Synthetic Observations of Simulated Radio Galaxies. I. Radio and X‐Ray Analysis

Tregillis

Jones

Ryu

2004

ApJ

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We present an extensive synthetic observational analysis of numerically simulated radio galaxies designed to explore the effectiveness of conventional observational analyses at recovering physical source properties. These are the first numerical simulations with sufficient physical detail to allow such a study. The present paper focuses on extraction of magnetic field properties from nonthermal intensity information. Synchrotron and inverse Compton intensities were effective in providing meaningful information about distributions and strengths of magnetic fields, although considerable care was called for in quantitative usage of the information. Correlations between radio and X-ray surface brightness correctly revealed useful dynamical relationships between particles and fields, for example. Magnetic field strength estimates derived from the ratio of X-ray to radio intensity were mostly within about a factor of 2 of the rms field strength along a given line of sight. When emissions along a given line of sight were dominated by regions close to the minimum energy/equipartition condition, the field strengths derived from the standard power-law spectrum minimum energy calculation were also reasonably close to actual field strengths, except when spectral aging was evident. Otherwise, biases in the minimum energy magnetic field estimation mirrored actual differences from equipartition. The ratio of the inverse Comptonestimated magnetic field to the minimum energy magnetic field provided a rough measure of the actual total energy in particles and fields in most instances, although this measure was accurate within only about an order of magnitude. This may provide a practical limit to the accuracy with which one may be able to establish the internal energy density or pressure of optically thin synchrotron sources.

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[ITAL]Chandra[/ITAL] Discovery of a 100 kiloparsec X-Ray Jet in PKS 0637−752

Cited by 186 publications

References 18 publications

Ruling Out Ic/CMB X-Rays in PKS 0637-752 and the Implications for Tev Emission From Large-Scale Quasar Jets

Ruling Out Ic/CMB X-Rays in PKS 0637-752 and the Implications for Tev Emission From Large-Scale Quasar Jets

Recent Progress in Understanding the Large Scale Jets of Powerful Quasars

Synthetic Observations of Simulated Radio Galaxies. I. Radio and X‐Ray Analysis

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