Tracing High-z Galaxies in X-rays with JWST and Chandra

TL;DR

This study uses JWST and Chandra data to analyze the correlation between the cosmic infrared background and the cosmic X-ray background, revealing significant high-redshift galaxy contributions and constraining the unresolved X-ray flux.

Contribution

It provides the first detailed measurement of the CIB-CXB cross-power spectrum at high redshifts using JWST and Chandra data, highlighting resolved X-ray emitting galaxies at z > 6.

Findings

Significant CIB-CXB cross-power detected at scales 1-1000''

High-redshift (z > 6) coherence indicates resolved X-ray galaxies

Approximately 94% of the X-ray background is resolved

Abstract

We leverage JWST data from the COSMOS-Web Survey in order to provide updated measurements on the auto-power spectrum of the now resolved Cosmic Infrared Background (CIB) and its coherence with the unresolved soft Cosmic X-ray Background (CXB) observed by Chandra at z > 6. Maps of the CIB in the F277W and F444W NIRCam filters are constructed with sources fainter than AB mag = 25 and cross-correlated with the CXB in the [0.5-2] keV band. We find that on scales between 1 and 1000'' the CIB-CXB cross-power in both NIRCam filters is statistically significant with signal-to-noise ratios (S/N) of 4.80 and 6.20 respectively from redshifts 0 < z < 13. In our high-z (6 < z < 13) interval we find coherence in both filters with a S/N of 7.32 and 5.39 respectively. These results suggest that there are X-ray emitting galaxies resolved by JWST, including star-forming galaxies (SFGs) and active galactic nuclei (AGNs). We fit the large-scale biasing of the IR sources producing the CIB as a function of z with results consistent with prior measurements and place constraints on the CXB flux and biasing at low- and high-z. The CXB flux measurements presented in this study suggest that approximately 94% of the [0.5-2] keV CXB is resolved, and this value is consistent within 2$\sigma$ with the complete resolution of the [0.5-2] keV CXB.