• DOI:10.1086/429558
• Corpus ID: 39743397

BULK COMPTONIZATION OF THE COSMIC MICROWAVE BACKGROUND BY EXTRAGALACTIC JETS AS A PROBE OF THEIR MATTER CONTENT

@article{Georganopoulos2005BULKCO,
  title={BULK COMPTONIZATION OF THE COSMIC MICROWAVE BACKGROUND BY EXTRAGALACTIC JETS AS A PROBE OF THEIR MATTER CONTENT},
  author={Markos Georganopoulos and Demosthenes Kazanas and Eric S. Perlman and Floyd W. Stecker},
  journal={The Astrophysical Journal},
  year={2005},
  volume={625},
  pages={656-666}
}

• M. Georganopoulos, D. Kazanas, +1 author F. Stecker
• Published 9 February 2005
• Physics
• The Astrophysical Journal

We propose a method for estimating the composition, i.e. the relative amounts of leptons and protons, of extragalactic jets which exhibit Chandra - detected knots in their kpc scale jets. The method relies on measuring, or setting upper limits on, the component of the Cosmic Microwave Background (CMB) radiation that is bulk-Comptonized by the cold electrons in the relativistically flowing jet. These measurements, along with modeling of the broadband knot emission that constrain the bulk Lorentz factor GAMMA of the jets, can yield estimates of the jet power carried by protons and leptons. We provide an explicit calculation of the spectrum of the bulk-Comptonized (BC) CMB component and apply these results to PKS 0637 - 752 and 3C 273, two superluminal quasars with Chandra - detected large scale jets. What makes these sources particularly suited for such a procedure is the absence of significant non-thermal jet emission in the 'bridge', the region between the core and the first bright jet knot, which guarantees that most of the electrons are cold there, leaving the BC scattered CMB radiation as the only significant source of photons in this region. At lambda = 3.6 - 8.0 microns, the most likely band to observe the BC scattered CMB emission, the Spitzer angular resolution (approximately 1" - 3") is considerably smaller than the the 'bridges' of these jets (approximately 10"), making it possible to both measure and resolve this emission.