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Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

Connor, Thomas and Bañados, Eduardo and Stern, Daniel and Carilli, Chris and Fabian, Andrew and Momjian, Emmanuel and Rojas-Ruiz, Sofía and Decarli, Roberto and Farina, Emanuele Paolo and Mazzucchelli, Chiara and Earnshaw, Hannah P. (2021) Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years. Astrophysical Journal, 911 (2). Art. No. 120. ISSN 0004-637X. doi:10.3847/1538-4357/abe710.

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We present deep (265 ks) Chandra X-ray observations of PSO J352.4034−15.3373, a quasar at z = 5.831 that, with a radio-to-optical flux ratio of R > 1000, is one of the radio-loudest quasars in the early universe and is the only quasar with observed extended radio jets of kiloparsec scale at z ≳ 6. Modeling the X-ray spectrum of the quasar with a power law, we find a best fit of Γ = 1.99^(+0.29)_(−0.28), leading to an X-ray luminosity of L₂₋₁₀ = 1.26^(+0.45)_(−0.33) × 10⁴⁵ erg s⁻¹ and an X-ray to UV brightness ratio of α_(OX) = −1.45 ± −0.11. We identify a diffuse structure 50 kpc (~8") to the NW of the quasar along the jet axis that corresponds to a 3σ enhancement in the angular density of emission and can be ruled out as a background fluctuation with a probability of P = 0.9985. While with few detected photons the spectral fit of the structure is uncertain, we find that it has a luminosity of L₂₋₁₀ ~ 10⁴⁴ erg s⁻¹. These observations therefore potentially represent the most distant quasar jet yet seen in X-rays. We find no evidence for excess X-ray emission where the previously reported radio jets are seen (which have an overall linear extent of 0.”28), and a bright X-ray point source located along the jet axis to the SE is revealed by optical and NIR imaging to not be associated with the quasar.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Connor, Thomas0000-0002-7898-7664
Bañados, Eduardo0000-0002-2931-7824
Stern, Daniel0000-0003-2686-9241
Carilli, Chris0000-0001-6647-3861
Fabian, Andrew0000-0002-9378-4072
Momjian, Emmanuel0000-0003-3168-5922
Rojas-Ruiz, Sofía0000-0003-2349-9310
Decarli, Roberto0000-0002-2662-8803
Farina, Emanuele Paolo0000-0002-6822-2254
Mazzucchelli, Chiara0000-0002-5941-5214
Earnshaw, Hannah P.0000-0001-5857-5622
Additional Information:© 2021. The American Astronomical Society. Received 2020 December 9; revised 2021 February 3; accepted 2021 February 15; published 2021 April 23. The work of T.C. and D.S. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. T.C.'s research was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, California Institute of Technology, administered by Universities Space Research Association under contract with NASA. The scientific results reported in this article are based on observations made by the Chandra X-ray Observatory. This research has made use of software provided by the Chandra X-ray Center (CXC) in the application package CIAO. Based on observations obtained at the international Gemini Observatory (GN-2020B-FT-101), a program of NSFs NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This work was enabled by observations made from the Keck and Gemini-North telescopes, located within the Maunakea Science Reserve and adjacent to the summit of Maunakea. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain and are grateful for the privilege of observing the universe from a place that is unique in both its astronomical quality and its cultural significance. Facilities: CXO - Chandra X-ray Observatory satellite, Gemini:Gillett (GMOS-N) - , Keck:I (MOSFIRE). - Software: BEHR (Park et al. 2006), CIAO (Fruscione et al. 2006), MARX (Davis et al. 2012), PyFITS (Barrett & Bridgman 1999), Synphot (STScI development Team 2018), WAVDETECT (Freeman et al. 2002), XSPEC (Arnaud 1996).
Funding AgencyGrant Number
NASA Postdoctoral ProgramUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:X-ray quasars; X-ray astronomy; Radio loud quasars; Quasars; Jets
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: X-ray quasars (1821); X-ray astronomy (1810); Radio loud quasars (1349); Quasars (1319); Jets (870)
Record Number:CaltechAUTHORS:20210504-080557186
Persistent URL:
Official Citation:Thomas Connor et al 2021 ApJ 911 120
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108954
Deposited By: Tony Diaz
Deposited On:05 May 2021 18:17
Last Modified:05 May 2021 18:17

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