New Article by graduate student Peter Breiding

Mon, 27 Nov 2017 09:24:54 -0500

“Fermi Non-detections of Four X-Ray Jet Sources and Implications for the IC/CMB Mechanism”

Peter Breiding¹, Eileen T. Meyer¹, Markos Georganopoulos1,2, M. E. Keenan¹, N. S. DeNigris¹, and Jennifer Hewitt¹

The Astrophysical Journal, Volume 849, Number 2

URL: http://iopscience.iop.org/article/10.3847/1538-4357/aa907a/meta

Abstract: Since its launch in 1999, the Chandra X-ray observatory has discovered several dozen X-ray jets associated with powerful quasars. In many cases, the X-ray spectrum is hard and appears to come from a second spectral component. The most popular explanation for the kpc-scale X-ray emission in these cases has been inverse-Compton (IC) scattering of Cosmic Microwave Background (CMB) photons by relativistic electrons in the jet (the IC/CMB model). Requiring the IC/CMB emission to reproduce the observed X-ray flux density inevitably predicts a high level of gamma-ray emission, which should be detectable with the Fermi Large Area Telescope (LAT). In previous work, we found that gamma-ray upper limits from the large-scale jets of 3C 273 and PKS 0637−752 violate the predictions of the IC/CMB model. Here, we present Fermi/LAT flux density upper limits for the X-ray jets of four additional sources: PKS 1136–135, PKS 1229–021, PKS 1354+195, and PKS 2209+080. We show that these limits violate the IC/CMB predictions at a very high significance level. We also present new Hubble Space Telescope observations of the quasar PKS 2209+080 showing a newly detected optical jet, and Atacama Large Millimeter/submillimeter Array band 3 and 6 observations of all four sources, which provide key constraints on the spectral shape that enable us to rule out the IC/CMB model.