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

doi:10.3847/1538-4357/aba2ca

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

School of Physics

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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 $\alpha_{ox}$ is calculated for each source using optical/UV data available in the literature. The $\alpha_{ox}$-UV relationship is compared with other quasar surveys, and an anti-correlation 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.

Original language	English
Article number	127
Number of pages	10
Journal	Astrophysical Journal
Volume	899
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/aba2ca
Publication status	Published - 20 Aug 2020

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Accepted to ApJ, 13 pages, 5 figures, 4 tables

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astro-ph.HE

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@article{692be72f429948e28d7052fd2f1975a1,

title = "X-ray Properties of Young Radio Quasars at z > 4.5",

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 $\alpha_{ox}$ is calculated for each source using optical/UV data available in the literature. The $\alpha_{ox}$-UV relationship is compared with other quasar surveys, and an anti-correlation 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. ",

keywords = "astro-ph.HE",

author = "Bradford Snios and Aneta Siemiginowska and Ma{\l}gosia Sobolewska and Cheung, {C. C.} and Vinay Kashyap and Giulia Migliori and Schwartz, {Daniel A.} and {\L}ukasz Stawarz and Worrall, {Diana M.}",

note = "Accepted to ApJ, 13 pages, 5 figures, 4 tables",

year = "2020",

month = aug,

day = "20",

doi = "10.3847/1538-4357/aba2ca",

language = "English",

volume = "899",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "2",

}

TY - JOUR

T1 - X-ray Properties of Young Radio Quasars at z > 4.5

AU - Snios, Bradford

AU - Siemiginowska, Aneta

AU - Sobolewska, Małgosia

AU - Cheung, C. C.

AU - Kashyap, Vinay

AU - Migliori, Giulia

AU - Schwartz, Daniel A.

AU - Stawarz, Łukasz

AU - Worrall, Diana M.

N1 - Accepted to ApJ, 13 pages, 5 figures, 4 tables

PY - 2020/8/20

Y1 - 2020/8/20

N2 - 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 $\alpha_{ox}$ is calculated for each source using optical/UV data available in the literature. The $\alpha_{ox}$-UV relationship is compared with other quasar surveys, and an anti-correlation 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.

AB - 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 $\alpha_{ox}$ is calculated for each source using optical/UV data available in the literature. The $\alpha_{ox}$-UV relationship is compared with other quasar surveys, and an anti-correlation 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.

KW - astro-ph.HE

U2 - 10.3847/1538-4357/aba2ca

DO - 10.3847/1538-4357/aba2ca

M3 - Article (Academic Journal)

SN - 0004-637X

VL - 899

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 127

ER -

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

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