2020/07/31 by Bradford Snios, Aneta Siemiginowska, Małgosia Sobolewska +6
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Luminosity #OVV quasar #Quasar #Redshift #Spectral index #Spectral line #astro-ph.HE
paper · pdf · doi:10.3847/1538-4357/aba2ca
Accepted to ApJ, 13 pages, 5 figures, 4 tables
openalex created_date 2020/07/10 · openalex publication_date 2020/08/01 · arxiv created 2020/08/03 · arxiv updated 2020/08/26 · openalex updated_date 2026/08/05
Abstract We present a comprehensive analysis of Chandra X-ray observations of 15 young radio quasars at redshifts 4.5 < z < 5.0. All sources are detected in the 0.5–7.0 keV energy band. Emission spectra are extracted, and the average photon index for the sample is measured to be 1.5 ± 0.1. Unabsorbed rest-frame 2–10 keV luminosities are found to range between (0.5–23.2) × 10 45 erg s −1 . The optical–X-ray power-law spectral index is calculated for each source using optical/UV data available in the literature. The –UV relationship is compared with other quasar surveys, and an anticorrelation is observed that agrees with independent estimates. Rest-frame radio and X-ray luminosities are established for the sample, and a correlation between the luminosities is detected. These multiwavelength results reinforce a lack of spectral evolution for quasars over a broad redshift range. We additionally identify three quasars from our multiwavelength analysis that are statistically significant outliers, with one source being a Compton-thick candidate in the early universe, and discuss each in detail.