A Multi-Wavelength Study of the Jet, Lobes and Core of the Quasar PKS 2101-490

TL;DR

This study combines multi-wavelength observations to analyze the jet, lobes, and core of quasar PKS 2101-490, modeling its emission mechanisms and jet dynamics, revealing a highly relativistic jet with specific physical properties.

Contribution

It provides a comprehensive multi-wavelength analysis of the quasar's jet, modeling X-ray emission via IC/CMB and constraining jet parameters with new observational data.

Findings

Jet remains highly relativistic hundreds of kpc from the nucleus

Detection of a radiative cooling break in the jet's synchrotron spectrum

IC/CMB model jet power is consistent with independent estimates

Abstract

We present a detailed study of the X-ray, optical and radio emission from the jet, lobes and core of the quasar PKS 2101-490 as revealed by new Chandra, HST and ATCA images. We extract the radio to X-ray spectral energy distributions from seven regions of the 13 arcsecond jet, and model the jet X-ray emission in terms of Doppler beamed inverse Compton scattering of the cosmic microwave background (IC/CMB) for a jet in a state of equipartition between particle and magnetic field energy densities. This model implies that the jet remains highly relativistic hundreds of kpc from the nucleus, with a bulk Lorentz factor Gamma ~ 6 and magnetic field of order 30 microGauss. We detect an apparent radiative cooling break in the synchrotron spectrum of one of the jet knots, and are able to interpret this in terms of a standard one-zone continuous injection model, based on jet parameters derived from the IC/CMB model. However, we note apparent substructure in the bright optical knot in one of the HST bands. We confront the IC/CMB model with independent estimates of the jet power, and find that the IC/CMB model jet power is consistent with the independent estimates, provided that the minimum electron Lorentz factor gamma_min > 50, and the knots are significantly longer than the jet width, as implied by de-projection of the observed knot lengths.