2020ApJ...900..189C -
Astrophys. J., 900, 189-189 (2020/September-2)
X-ray observations of a [C II]-bright, z = 6.59 quasar/companion system.
CONNOR T., BANADOS E., MAZZUCCHELLI C., STERN D., DECARLI R., FAN X., FARINA E.P., LUSSO E., NEELEMAN M. and WALTER F.
Abstract (from CDS):
We present deep Chandra observations of PSO J231.6576-20.8335, a quasar at redshift z = 6.59 with a nearby (∼8 proper kpc) companion galaxy. The Atacama Large Millimeter/submillimeter Array observed both the quasar and companion to be bright in [C II], and the system has significant extended Lyα emission around the quasar, suggesting that a galaxy merger is ongoing. Unlike previous studies of two similar systems, and despite observing the system with Chandra for 140 ks, we do not detect the companion in X-rays. The quasar itself is detected, but only 13.3–3.7+4.8 net counts are observed. From a basic spectral analysis, the X-ray spectrum of the quasar is soft (hardness ratio of H R =-0.60–0.27+0.17, power-law index of Γ=2.6–0.9+1.0), which results in a rest-frame X-ray luminosity comparable to other bright quasars (L2–10=1.09–0.70+2.20×1045 erg s–1) despite the faint observed X-ray flux. We highlight two possible interpretations of this result: the quasar has a steep value of Γ-potentially related to observed ongoing Eddington accretion-thereby pushing much of the emission out of our observed band, or the quasar has a more normal spectrum (Γ ∼ 2) but is therefore less X-ray luminous (L2–10∼0.6×1045 erg s–1).
Abstract Copyright:
© 2020. The American Astronomical Society. All rights reserved.
Journal keyword(s):
X-ray quasars - X-ray astronomy - Galaxy mergers - Quasars - Quasar-galaxy pairs
Simbad objects:
10
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