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Title: A quasar-galaxy merger at z ∼ 6.2: Black hole mass and quasar properties from the NIRSpec spectrum
We present JWST/NIRSpec integral field data of the quasar PJ308-21 atz = 6.2342. As shown by previous ALMA and HST imaging, the quasar has two companion sources, interacting with the quasar host galaxy. The high-resolution G395H/290LP NIRSpec spectrum covers the 2.87 − 5.27 μm wavelength range and shows the rest-frame optical emission of the quasar with exquisite quality (signal-to-noise ratio ∼100 − 400 per spectral element). Based on the Hβline from the broad line region, we obtain an estimate of the black hole massMBH, Hβ ∼ 2.7 × 109 M⊙. This value is within a factor ≲1.5 of the Hα-based black hole mass from the same spectrum (MBH, Hα ∼ 1.93 × 109 M⊙) and is consistent with a previous estimate relying on the Mg IIλ2799 line (MBH, MgII ∼ 2.65 × 109 M⊙). All theseMBHestimates are within the ∼0.5 dex intrinsic scatter of the adopted mass calibrations. The high Eddington ratio of PJ308-21λEdd, Hβ ∼ 0.67 (λEdd, Hα ∼ 0.96) is in line with the overall quasar population atz ≳ 6. The relative strengths of the [O III], Fe II, and Hβlines are consistent with the empirical “Eigenvector 1” correlations as observed for low redshift quasars. We find evidence for blueshifted [O III]λ5007 emission with a velocity offset Δv[O III] = −1922 ± 39 km s−1from the systemic velocity and a full width at half maximum (FWHM)FWHM([O III]) = 2776−74+75km s−1. This may be the signature of outflowing gas from the nuclear region, despite the true values of Δv[O III]andFWHM([O III]) likely being more uncertain due to the blending with Hβand Fe IIlines. Our study demonstrates the unique capabilities of NIRSpec in capturing quasar spectra at cosmic dawn and studying their properties in unprecedented detail.  more » « less
Award ID(s):
2308258 2307171
PAR ID:
10520626
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; ; ; ; ; ; ; ; ; ; ; ; ; ; « less
Publisher / Repository:
Astronomy & Astrophysics
Date Published:
Journal Name:
Astronomy & Astrophysics
Volume:
685
ISSN:
0004-6361
Page Range / eLocation ID:
A121
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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