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1. Gemini Near Infrared Spectrograph–Distant Quasar Survey: Prescriptions for Calibrating UV-based Estimates of Supermassive Black Hole Masses in High-redshift Quasars

   https://doi.org/10.3847/1538-4357/acd04b  

   Dix, Cooper ; Matthews, Brandon ; Shemmer, Ohad ; Brotherton, Michael S. ; Myers, Adam D. ; Andruchow, I. ; Brandt, W. N. ; Ferrero, Gabriel A. ; Green, Richard ; Lira, Paulina ; et al ( June 2023 , The Astrophysical Journal)

   The most reliable single-epoch supermassive black hole mass (M_BH) estimates in quasars are obtained by using the velocity widths of low-ionization emission lines, typically the Hβλ4861 line. Unfortunately, this line is redshifted out of the optical band atz≈ 1, leavingM_BHestimates to rely on proxy rest-frame ultraviolet (UV) emission lines, such as Civλ1549 or Mgiiλ2800, which contain intrinsic challenges when measuring, resulting in uncertainM_BHestimates. In this work, we aim at correctingM_BHestimates derived from the Civand Mgiiemission lines based on estimates derived from the Hβemission line. We find that employing the equivalent width of Civin derivingM_BHestimates based on Mgiiand Civprovides values that are closest to those obtained from Hβ. We also provide prescriptions to estimateM_BHvalues when only Civ, only Mgii, and both Civand Mgiiare measurable. We find that utilizing both emission lines, where available, reduces the scatter of UV-basedM_BHestimates by ∼15% when compared to previous studies. Lastly, we discuss the potential of our prescriptions to provide more accurate and precise estimates ofM_BHgiven a much larger sample of quasars at 3.20 ≲z≲ 3.50, where both Mgiiand Hβcan be measured in the same near-infrared spectrum.

    

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2. Gemini Near Infrared Spectrograph–Distant Quasar Survey: Augmented Spectroscopic Catalog and a Prescription for Correcting UV-based Quasar Redshifts

   https://doi.org/10.3847/1538-4357/acd04c  

   Matthews, Brandon M. ; Dix, Cooper ; Shemmer, Ohad ; Brotherton, Michael S. ; Myers, Adam D. ; Andruchow, I. ; Brandt, W. N. ; Gallagher, S. C. ; Green, Richard ; Lira, Paulina ; et al ( June 2023 , The Astrophysical Journal)

   Quasars atz≳ 1 most often have redshifts measured from rest-frame ultraviolet emission lines. One of the most common such lines, Civλ1549, shows blueshifts up to ≈5000 km s⁻¹and in rare cases even higher. This blueshifting results in highly uncertain redshifts when compared to redshift determinations from rest-frame optical emission lines, e.g., from the narrow [Oiii]λ5007 feature. We present spectroscopic measurements for 260 sources at 1.55 ≲z≲ 3.50 having −28.0 ≲M_i≲ − 30.0 mag from the Gemini Near Infrared Spectrograph–Distant Quasar Survey (GNIRS-DQS) catalog, augmenting the previous iteration, which contained 226 of the 260 sources whose measurements are improved upon in this work. We obtain reliable systemic redshifts based on [Oiii]λ5007 for a subset of 121 sources, which we use to calibrate prescriptions for correcting UV-based redshifts. These prescriptions are based on a regression analysis involving Civfull-width-at-half-maximum intensity and equivalent width, along with the UV continuum luminosity at a rest-frame wavelength of 1350 Å. Applying these corrections can improve the accuracy and the precision in the Civ-based redshift by up to ∼850 km s⁻¹and ∼150 km s⁻¹, respectively, which correspond to ∼8.5 and ∼1.5 Mpc in comoving distance atz= 2.5. Our prescriptions also improve the accuracy of the best available multifeature redshift determination algorithm by ∼100 km s⁻¹, indicating that the spectroscopic properties of the Civemission line can provide robust redshift estimates for high-redshift quasars. We discuss the prospects of our prescriptions for cosmological and quasar studies utilizing upcoming large spectroscopic surveys.

    

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3. A quasar-galaxy merger at z ∼ 6.2: Black hole mass and quasar properties from the NIRSpec spectrum

   https://doi.org/10.1051/0004-6361/202348535  

   Loiacono, Federica ; Decarli, Roberto ; Mignoli, Marco ; Farina, Emanuele Paolo ; Bañados, Eduardo ; Bosman, Sarah ; Eilers, Anna-Christina ; Schindler, Jan-Torge ; Strauss, Michael A ; Vestergaard, Marianne ; et al ( May 2024 , Astronomy & Astrophysics)

   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 massM_BH, Hβ ∼ 2.7 × 10⁹ M_⊙. This value is within a factor ≲1.5 of the Hα-based black hole mass from the same spectrum (M_BH, Hα ∼ 1.93 × 10⁹ M_⊙) and is consistent with a previous estimate relying on the Mg IIλ2799 line (M_BH, MgII ∼ 2.65 × 10⁹ M_⊙). All theseM_BHestimates are within the ∼0.5 dex intrinsic scatter of the adopted mass calibrations. The high Eddington ratio of PJ308-21λ_Edd, Hβ ∼ 0.67 (λ_Edd, 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.

    

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4. Chemical abundance of z ~ 6 quasar broad-line regions in the XQR-30 sample

   https://doi.org/10.1093/mnras/stac1001  

   Lai, Samuel ; Bian, Fuyan ; Onken, Christopher A. ; Wolf, Christian ; Mazzucchelli, Chiara ; Bañados, Eduardo ; Bischetti, Manuela ; Bosman, Sarah E. I. ; Becker, George ; Cupani, Guido ; et al ( April 2022 , Monthly Notices of the Royal Astronomical Society)

   The elemental abundances in the broad-line regions of high-redshift quasars trace the chemical evolution in the nuclear regions of massive galaxies in the early Universe. In this work, we study metallicity-sensitive broad emission-line flux ratios in rest-frame UV spectra of 25 high-redshift (5.8 < z < 7.5) quasars observed with the VLT/X-shooter and Gemini/GNIRS instruments, ranging over $\log \left({{M}_{\rm {BH}}/\rm {M}_{\odot }}\right) = 8.4-9.8$ in black hole mass and $\log \left(\rm {L}_{\rm {bol}}/\rm {erg \, s}^{-1}\right) = 46.7-47.7$ in bolometric luminosity. We fit individual spectra and composites generated by binning across quasar properties: bolometric luminosity, black hole mass, and blueshift of the C iv line, finding no redshift evolution in the emission-line ratios by comparing our high-redshift quasars to lower redshift (2.0 < z < 5.0) results presented in the literature. Using cloudy-based locally optimally emitting cloud photoionization model relations between metallicity and emission-line flux ratios, we find the observable properties of the broad emission lines to be consistent with emission from gas clouds with metallicity that are at least 2–4 times solar. Our high-redshift measurements also confirm that the blueshift of the C iv emission line is correlated with its equivalent width, which influences line ratios normalized against C iv. When accounting for the C iv blueshift, we find that the rest-frame UV emission-line flux ratios do not correlate appreciably with the black hole mass or bolometric luminosity.

    

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5. Probing Early Supermassive Black Hole Growth and Quasar Evolution with Near-infrared Spectroscopy of 37 Reionization-era Quasars at 6.3 < z ≤ 7.64

   https://doi.org/10.3847/1538-4357/ac2b32  

   Yang, Jinyi ; Wang, Feige ; Fan, Xiaohui ; Barth, Aaron J. ; Hennawi, Joseph F. ; Nanni, Riccardo ; Bian, Fuyan ; Davies, Frederick B. ; Farina, Emanuele P. ; Schindler, Jan-Torge ; et al ( December 2021 , The Astrophysical Journal)

   Abstract We report the results of near-infrared spectroscopic observations of 37 quasars in the redshift range 6.3 < z ≤ 7.64, including 32 quasars at z > 6.5, forming the largest quasar near-infrared spectral sample at this redshift. The spectra, taken with Keck, Gemini, VLT, and Magellan, allow investigations of central black hole mass and quasar rest-frame ultraviolet spectral properties. The black hole masses derived from the Mg ii emission lines are in the range (0.3–3.6) × 10 9 M ⊙ , which requires massive seed black holes with masses ≳10 3 –10 4 M ⊙ , assuming Eddington accretion since z = 30. The Eddington ratio distribution peaks at λ Edd ∼ 0.8 and has a mean of 1.08, suggesting high accretion rates for these quasars. The C iv –Mg ii emission-line velocity differences in our sample show an increase of C iv blueshift toward higher redshift, but the evolutionary trend observed from this sample is weaker than the previous results from smaller samples at similar redshift. The Fe ii /Mg ii flux ratios derived for these quasars up to z = 7.6, compared with previous measurements at different redshifts, do not show any evidence of strong redshift evolution, suggesting metal-enriched environments in these quasars. Using this quasar sample, we create a quasar composite spectrum for z > 6.5 quasars and find no significant redshift evolution of quasar broad emission lines and continuum slope, except for a blueshift of the C iv line. Our sample yields a strong broad absorption line quasar fraction of ∼24%, higher than the fractions in lower-redshift quasar samples, although this could be affected by small sample statistics and selection effects. 

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