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arXiv · 2007.01342

X-ray Properties of Young Radio Quasars at z > 4.5

Bradford Snios·Aneta Siemiginowska·Małgosia Sobolewska·C. C. Cheung·Vinay Kashyap·Giulia Migliori·Daniel A. Schwartz·Łukasz Stawarz·Diana M. Worrall
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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 $1.5\pm0.1$. Unabsorbed rest-frame $2-10$ keV luminosities are found to range between $(0.5-23.2) \times 10^{45}$ erg s$^{-1}$. The optical-X-ray power-law spectral index $α_{ox}$ is calculated for each source using optical/UV data available in the literature. The $α_{ox}$-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.

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Bradford Snios, Aneta Siemiginowska, Małgosia Sobolewska, C. C. Cheung, Vinay Kashyap, Giulia Migliori, Daniel A. Schwartz, Łukasz Stawarz, Diana M. Worrall. 2020-08-03. X-ray Properties of Young Radio Quasars at z > 4.5. https://doi.org/10.3847/1538-4357%2Faba2ca

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