Abstract Luminous quasars are powerful targets to investigate the role of feedback from supermassive black holes (BHs) in regulating the growth phases of BHs themselves and of their host galaxies, up to the highest redshifts. Here we investigate the cosmic evolution of the occurrence and kinematics of BH-driven outflows, as traced by broad absorption line (BAL) features, due to the C iv ionic transition. We exploit a sample of 1935 quasars at z = 2.1–6.6 with bolometric luminosity log( L bol /erg s −1 ) ≳ 46.5, drawn from the Sloan Digital Sky Survey and from the X-Shooter legacy survey of Quasars at the Reionization Epoch (XQR-30). We consider rest-frame optical bright quasars to minimize observational biases due to quasar selection criteria. We apply a homogeneous BAL-identification analysis, based on employing composite template spectra to estimate the quasar intrinsic emission. We find a BAL quasar fraction close to 20% at z ∼ 2–4, while it increases to almost 50% at z ∼ 6. The velocity and width of the BAL features also increase at z ≳ 4.5. We exclude the possibility that the redshift evolution of the BAL properties is due to differences in terms of quasar luminosity and accretion rate. These results suggest significant BH feedback occurring in the 1 Gyr old universe, likely affecting the growth of BHs and, possibly, of their host galaxies, as supported by models of early BH and galaxy evolution.
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This content will become publicly available on June 29, 2024
A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): A First Look at the Rest-frame Optical Spectra of z > 6.5 Quasars Using JWST
Abstract Studies of rest-frame optical emission in quasars at z > 6 have historically been limited by the wavelengths accessible by ground-based telescopes. The James Webb Space Telescope (JWST) now offers the opportunity to probe this emission deep into the reionization epoch. We report the observations of eight quasars at z > 6.5 using the JWST/NIRCam Wide Field Slitless Spectroscopy as a part of the “A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE)” program. Our JWST spectra cover the quasars’ emission between rest frame ∼4100 and 5100 Å. The profiles of these quasars’ broad H β emission lines span a full width at half maximum from 3000 to 6000 km s −1 . The H β -based virial black hole (BH) masses, ranging from 0.6 to 2.1 billion solar masses, are generally consistent with their Mg ii -based BH masses. The new measurements based on the more reliable H β tracer thus confirm the existence of a billion solar-mass BHs in the reionization epoch. In the observed [O iii ] λ λ 4960,5008 doublets of these luminous quasars, broad components are more common than narrow core components (≤ 1200 km s −1 ), and only one quasar shows stronger narrow components than broad. Two quasars exhibit significantly broad and blueshifted [O iii ] emission, thought to trace galactic-scale outflows, with median velocities of −610 and −1430 km s −1 relative to the [C ii ] 158 μ m line. All eight quasars show strong optical Fe ii emission and follow the eigenvector 1 relations defined by low-redshift quasars. The entire ASPIRE program will eventually cover 25 quasars and provide a statistical sample for the studies of the BHs and quasar spectral properties.
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- Award ID(s):
- 1909933
- NSF-PAR ID:
- 10450530
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Date Published:
- Journal Name:
- The Astrophysical Journal Letters
- Volume:
- 951
- Issue:
- 1
- ISSN:
- 2041-8205
- Page Range / eLocation ID:
- L5
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract 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 Hβ λ 4861 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 Civ λ 1549 or Mgii λ 2800, which contain intrinsic challenges when measuring, resulting in uncertainM BHestimates. In this work, we aim at correctingM BHestimates derived from the Civ and Mgii emission lines based on estimates derived from the Hβ emission line. We find that employing the equivalent width of Civ in derivingM BHestimates based on Mgii and Civ provides values that are closest to those obtained from Hβ . We also provide prescriptions to estimateM BHvalues when only Civ , only Mgii , and both Civ and Mgii are 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 Mgii and Hβ can be measured in the same near-infrared spectrum. -
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Abstract Quasars at
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