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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
Citation
Meyer, ET and Georganopoulos, M and Sparks, WB and Godfrey, L and Lovell, JEJ and Perlman, E, Ruling out IC/CMB X-Rays in PKS 0637-752 and the implications for TEV emission from large-scale quasar jets, Astrophysical Journal, 805, (2) Article 154. ISSN 0004-637X (2015) [Refereed Article]
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Copyright Statement
© 2015. The American Astronomical Society. All rights reserved.
DOI: doi:10.1088/0004-637X/805/2/154
Abstract
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.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | galaxies: active, galaxies: jets, quasars: individual: PKS 0637-752, 3C 273 |
| Research Division: | Physical Sciences |
| Research Group: | Astronomical sciences |
| Research Field: | Cosmology and extragalactic astronomy |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding knowledge |
| Objective Field: | Expanding knowledge in the physical sciences |
| UTAS Author: | Lovell, JEJ (Dr Jim Lovell) |
| ID Code: | 105943 |
| Year Published: | 2015 |
| Web of Science® Times Cited: | 61 |
| Deposited By: | Mathematics and Physics |
| Deposited On: | 2016-01-20 |
| Last Modified: | 2017-11-03 |
| Downloads: | 190 View Download Statistics |
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