Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe's First Billion Years
Abstract
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 ${\rm{\Gamma }}={1.99}_{-0.28}^{+0.29}$ , leading to an X-ray luminosity of ${L}_{2\mbox{--}10}={1.26}_{-0.33}^{+0.45}\times {10}^{45}\ \mathrm{erg}\ {{\rm{s}}}^{-1}$ and an X-ray to UV brightness ratio of αOX = -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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2021
- DOI:
- arXiv:
- arXiv:2103.03879
- Bibcode:
- 2021ApJ...911..120C
- Keywords:
-
- X-ray quasars;
- X-ray astronomy;
- Radio loud quasars;
- Quasars;
- Jets;
- 1821;
- 1810;
- 1349;
- 1319;
- 870;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 16 pages, 7 Figures. Accepted for publication the Astrophysical Journal