Discovery of Candidate X-ray Jets in High-Redshift Quasars

TL;DR

This study reports the detection of X-ray jets in high-redshift quasars using Chandra observations, revealing that jet emission mechanisms are consistent across cosmic time and providing insights into quasar jet properties at early epochs.

Contribution

First detection of X-ray jets in high-redshift quasars, demonstrating that jet emission mechanisms are similar to those in nearby systems.

Findings

X-ray jets detected in 5 out of 14 quasars

Jet-to-core X-ray flux ratios consistent with nearby jets

Upper limits on jet X-ray emission for undetected cases

Abstract

We present Chandra X-ray observations of 14 radio-loud quasars at redshifts $3 < z < 4$, selected from a well-defined sample. All quasars are detected in the 0.5-7.0 keV energy band, and resolved X-ray features are detected in five of the objects at distances of 1-12" from the quasar core. The X-ray features are spatially coincident with known radio features for four of the five quasars. This indicates that these systems contain X-ray jets. X-ray fluxes and luminosities are measured, and jet-to-core X-ray flux ratios are estimated. The flux ratios are consistent with those observed for nearby jet systems, suggesting that the observed X-ray emission mechanism is independent of redshift. For quasars with undetected jets, an upper limit on the average X-ray jet intensity is estimated using a stacked image analysis. Emission spectra of the quasar cores are extracted and modeled to obtain best-fit photon indices, and an Fe K emission line is detected from one quasar in our sample. We compare X-ray spectral properties with optical and radio emission in the context of both our sample and other quasar surveys.