A Multi-band Study of the remarkable Jet in Quasar 4C+19.44

TL;DR

This study provides a detailed multi-wavelength analysis of the longest straight quasar jet, revealing consistent spectral indices and magnetic field properties, and discusses possible X-ray emission mechanisms.

Contribution

It offers the first comprehensive multi-band imaging and spectral analysis of the quasar 4C+19.44's jet, with insights into its emission processes and physical conditions.

Findings

Radio and X-ray spectral indices are consistent at 0.80.

Jet structure extends beyond the radio emission and connects to lobes.

Magnetic field and Doppler factors are relatively constant along the jet.

Abstract

We present arc-second-resolution data in the radio, IR, optical and X-ray for 4C+19.44 (=PKS 1354+195), the longest and straightest quasar jet with deep X-ray observations. We report results from radio images with half to one arc-second angular resolution at three frequencies, plus HST and Spitzer data. The Chandra data allow us to measure the X-ray spectral index in 10 distinct regions along the 18 arcsec jet and compare with the radio index. The radio and X-ray spectral indices of the jet regions are consistent with a value of $\alpha =0.80$ throughout the jet, to within 2 sigma uncertainties. The X-ray jet structure to the south extends beyond the prominent radio jet and connects to the southern radio lobe, and there is extended X-ray emission in the direction of the unseen counter jet and coincident with the northern radio lobe. This jet is remarkable since its straight appearance over a large distance allows the geometry factors to be taken as fixed along the jet. Using the model of inverse Compton scattering of the cosmic microwave background (iC/CMB) by relativistic electrons, we find that the magnetic field strengths and Doppler factors are relatively constant along the jet. If instead the X-rays are synchrotron emission, they must arise from a population of electrons distinct from the particles producing the radio synchrotron spectrum.