A quasar-galaxy merger at <i>z</i> ∼ 6.2: Black hole mass and quasar properties from the NIRSpec spectrum
Bibliographic record
Abstract
We present JWST/NIRSpec integral field data of the quasar PJ308-21 at z = 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 H β line from the broad line region, we obtain an estimate of the black hole mass M BH, H β ∼ 2.7 × 10 9 M ⊙ . This value is within a factor ≲1.5 of the H α -based black hole mass from the same spectrum ( M BH, H α ∼ 1.93 × 10 9 M ⊙ ) and is consistent with a previous estimate relying on the Mg II λ 2799 line ( M BH, MgII ∼ 2.65 × 10 9 M ⊙ ). All these M BH estimates are within the ∼0.5 dex intrinsic scatter of the adopted mass calibrations. The high Eddington ratio of PJ308-21 λ Edd, H β ∼ 0.67 ( λ Edd, H α ∼ 0.96) is in line with the overall quasar population at z ≳ 6. The relative strengths of the [O III ], Fe II , and H β lines are consistent with the empirical “Eigenvector 1” correlations as observed for low redshift quasars. We find evidence for blueshifted [O III ] λ 5007 emission with a velocity offset Δ v [O III] = −1922 ± 39 km s −1 from the systemic velocity and a full width at half maximum (FWHM) FWHM ([O III ]) = 2776 −74 +75 km s −1 . This may be the signature of outflowing gas from the nuclear region, despite the true values of Δ v [O III] and FWHM ([O III ]) likely being more uncertain due to the blending with H β and Fe II lines. Our study demonstrates the unique capabilities of NIRSpec in capturing quasar spectra at cosmic dawn and studying their properties in unprecedented detail.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".