James Webb Space Telescope Feed Post

Arxiv: Tracing high-z Galaxies in X-rays with JWST and Chandra Published: 2/13/2025 9:00:07 PM Updated: 2/13/2025 9:00:07 PM

Paper abstract: We leverage JWST data from the COSMOS-Web Survey in order to provide updatedmeasurements on the auto-power spectrum of the now resolved Cosmic InfraredBackground (CIB) and its coherence with the unresolved soft Cosmic X-rayBackground (CXB) observed by Chandra at z > 6. Maps of the CIB in the F277W andF444W NIRCam filters are constructed with sources fainter than AB mag = 25 andcross-correlated with the CXB in the [0.5-2] keV band. We find that on scalesbetween 1 and 1000'' the CIB-CXB cross-power in both NIRCam filters isstatistically significant with signal-to-noise ratios (S/N) of 4.80 and 6.20respectively from redshifts 0 < z < 13. In our high-z (6 < z < 13) interval wefind coherence in both filters with a S/N of 7.32 and 5.39 respectively. Theseresults suggest that there are X-ray emitting galaxies resolved by JWST,including star-forming galaxies (SFGs) and active galactic nuclei (AGNs). Wefit the large-scale biasing of the IR sources producing the CIB as a functionof z with results consistent with prior measurements and place constraints onthe CXB flux and biasing at low- and high-z. The CXB flux measurementspresented in this study suggest that approximately 94% of the [0.5-2] keV CXBis resolved, and this value is consistent within 2\sigma with the completeresolution of the [0.5-2] keV CXB.