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

Meyer, Eileen T.; Georganopoulos, Markos; Sparks, W. B.; Godfrey, L.; Lovell, J. E. J.; Perlman, Eric S.

doi:10.1088/0004-637x/805/2/154

Cited by 82 publications

(131 citation statements)

References 47 publications

(73 reference statements)

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“…Observations at HE γ-ray energies have been used to rule out the IC/CMB model in a number of extended X-ray jets [11,12]. The resulting IC spectrum overpredicts the upper limits derived from Fermi observations, invalidating the model in the sources analyzed by [11,12].…”

Section: Discussionmentioning

confidence: 99%

AP Librae: The Extended Jet as the Source of VHE Emission?

Zacharias

Wagner

2016

Galaxies

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Abstract:The LBL AP Librae has been detected in the TeV gamma-ray range, which is unexpected for this kind of blazar. The broad-band SED cannot be explained by a one-zone model, and especially fails in the TeV domain. An extended jet has been detected on arcsec scales both in radio and X-ray frequencies. The spectral index of the X-ray band indicates an inverse Compton origin. Using an IC/CMB model, the TeV emission can be successfully modeled as originating in the extended jet. Several arguments in favor of this model, as well as observational tests, will be presented. The observations suggest that acceleration of particles to very high energies is still efficient at large distances from the core.

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Section: Discussionmentioning

confidence: 99%

AP Librae: The Extended Jet as the Source of VHE Emission?

Zacharias

Wagner

2016

Galaxies

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“…A γ-ray discriminant-proposed [28] and recently applied [14,30] by our group-is based on the fact that the same electrons that produce the radio to near-IR synchrotron emission must up-scatter the CMB photons to produce an X-ray to GeV component whose amplitude depends solely on the ratio B/δ, where B is the magnetic field of the emitting region. The requirement that the IC/CMB emission reproduces the observed X-ray emission sets B/δ, which in turn sets the level of the anticipated γ-ray emission without any freedom.…”

Section: Fermi Rules Out Ic/cmb For 3c 273 and Pks 0637-752mentioning

confidence: 99%

“…The unexpected X-ray detection of the jet (separately from the core) led to the original suggestion that quasar jets remain highly relativistic to kpc scales; (b) At right, we plot the total radio-X-ray spectral SED for the large-scale jet of PKS 0637-752 (black points). The hard spectrum in the X-rays clearly indicates a separate spectral component, but both a synchrotron (yellow line) and an inverse Compton (black line) interpretation were plausible before the Fermi upper limits ruled out the latter for this source [14].…”

Section: Introductionmentioning

confidence: 95%

“…It has been proposed [15,16] that the X-ray emission is due to the IC/CMB process, requiring relativistic jets (bulk Γ ∼ [10][11][12][13][14][15][16][17][18][19][20] oriented close to the line of sight and an electron energy distribution (EED) extending down to Lorentz factors γ ∼ 30-much lower than the γ ∼ 10 3 -10 4 traced by GHz emission-to explain the X-ray emission. In view of the low radiative efficiency of these electrons, reproducing the observed X-ray flux requires high power, sometimes in excess of the Eddington luminosity of the central black hole [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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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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“…Despite this early evidence, the data for a number of these jets are no longer consistent with a boosted IC/CMB model. Meyer et al (2015) used gamma-ray observations to disprove the boosted IC/CMB model for PKS 0637−572, which had previously been the prototypical example of a boosted IC/CMB jet (Tavecchio et al 2000;Celotti et al 2001). Meyer & Georganopoulos (2014) also used gamma-ray observations to rule out a relativistically boosted jet in 3C 273, building on the work of Jester et al (2007) and Uchiyama et al (2006).…”

Section: Introductionmentioning

confidence: 99%

Optical Detection of the Pictor a Jet and Tidal Tail: Evidence Against an Ic/CMB Jet

Gentry

Marshall

Hardcastle

et al. 2015

ApJ

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New images of the FR II radio galaxy Pictor A from the Hubble Space Telescope reveal a previously undiscovered tidal tail, as well as a number of jet knots coinciding with a known X-ray and radio jet. The tidal tail is approximately 5″ wide (3 kpc projected), starting 18″ (12 kpc) from the center of Pictor A, and extends more than 90″ (60 kpc). The knots are part of a jet observed to be about 4′ (160 kpc) long, extending to a bright hotspot. These images are the first optical detections of this jet, and by extracting knot flux densities through three filters, we set constraints on emission models. While the radio and optical flux densities are usually explained by synchrotron emission, there are several emission mechanisms that might be used to explain the X-ray flux densities. Our data rule out Doppler-boosted inverse Compton scattering as a source of the high-energy emission. Instead, we find that the observed emission can be well described by synchrotron emission from electrons with a low-energy index (p 2 ) that dominates the radio band, while a high-energy index (p 3 ) is needed for the X-ray band and the transition occurs in the optical/infrared band. This model is consistent with a continuous electron injection scenario.

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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

Cited by 82 publications

References 47 publications

AP Librae: The Extended Jet as the Source of VHE Emission?

AP Librae: The Extended Jet as the Source of VHE Emission?

Recent Progress in Understanding the Large Scale Jets of Powerful Quasars

Optical Detection of the Pictor a Jet and Tidal Tail: Evidence Against an Ic/CMB Jet

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