13 results for "Jun-Rong Liu"
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Journal Article
Fermi Detection of γ-Rays from the Radio-quiet Seyfert Galaxy NGC 3281
We report the detection of significant γ -ray emission with the Fermi Large Area Telescope from the radio-quiet Seyfert 2 galaxy NGC 3281, with a luminosity of 5.9 (±1.7) × 10 ^41 erg s ^−1 at a significance of 6.22 σ (TS = 42.81). The power-law photon index is 2.61 (±0.24), indicative of a soft…
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Journal Article
Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: Contribution to Active Galactic Nuclei Disk Viscosity
It is widely believed that stellar-mass black holes (sMBHs) exist within the accretion disks of active galactic nuclei (AGN), forming a distinct population termed “accretion-modified star” (AMS). Gas from the dense disk accretes onto these AMSs, dissipating substantial gravitational energy through…
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Journal Article
Optically Thick Outflow Driven by Supercritical Accretion May Explain Little Red Dots
Recent JWST observations have revealed a population of compact, optically red sources known as Little Red Dots (LRDs). A popular interpretation is that LRDs host massive black holes embedded in dense gaseous envelopes, yet the physical origin of such envelopes remains unclear. We propose that the…
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Journal Article
Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: Observational Characteristics in Different Regions of the Disks
Stars and compact objects embedded in accretion disks of active galactic nuclei (AGNs), dubbed accretion-modified stars (AMSs), often experience hyper-Eddington accretion in the dense gas environment, resulting in powerful outflows as the Bondi explosion and formation of cavities. The varying gas…
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Journal Article
CH4 emissions and reduction potential in wastewater treatment in China
The treatment of domestic and industrial wastewater is one of the major sources of CH4 in the Chinese waste sector. On the basis of statistical data and country-specific emission factors, using IPCC methodology, the characteristics of CH4 emissions from wastewater treatment in China were analyzed…
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Journal Article
Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: The Low-luminosity Cases and an Application to Sgr A*
In this paper, we investigate the astrophysical processes of stellar-mass black holes (sMBHs) embedded in advection-dominated accretion flows (ADAFs) of supermassive black holes (SMBHs) in low-luminosity active galactic nuclei. The sMBH is undergoing Bondi accretion at a rate lower than the SMBH…
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Journal Article
Star Formation in Self-gravitating Disks in Active Galactic Nuclei. III. Efficient Production of Iron and Infrared Spectral Energy Distributions
Strong iron lines are a common feature of the optical spectra of active galactic nuclei (AGNs) and quasars from z ∼ 6−7 to the local universe, and [Fe/Mg] ratios do not show cosmic evolution. During active episodes, accretion disks surrounding supermassive black holes (SMBHs) inevitably form stars…
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Journal Article
Spectroastrometry and Reverberation Mapping of Active Galactic Nuclei. I. The Hβ Broad-line Region Structure and Black Hole Masses of Five Quasars
We conduct a reverberation mapping (RM) campaign to spectroscopically monitor a sample of selected bright active galactic nuclei with large anticipated broad-line region (BLR) sizes adequate for spectroastrometric (SA) observations by the GRAVITY instrument on the Very Large Telescope…
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Journal Article
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. XIV. Long-duration High-cadence Reverberation Mapping Results for 11 PG Quasars
We report the results of a long-duration high-cadence reverberation mapping campaign of a second batch of 11 PG quasars using the 2.2 m telescope at the Calar Alto Observatory. This follows a similar earlier study of another sample of 15 objects reported by C. Hu et al. (2021). Among the 11 PG…
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Journal Article
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. XV. Reverberation Mapping of Mg ii Emission Lines
As the 15th paper in a series reporting on a large reverberation mapping (RM) campaign of super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs), we present the results of measurements of the Mg ii lines in 18 SEAMBHs monitored spectroscopically from 2017 to 2024…
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Journal Article
Spectroastrometry and Reverberation Mapping of Active Galactic Nuclei. II. Measuring Geometric Distances and Black Hole Masses of Four Nearby Quasars
The geometric distances of active galactic nuclei (AGNs) are challenging to measure because of their exceptionally compact structure, yet vast cosmic distances. A combination of spectroastrometry and reverberation mapping (SARM) of broad-line regions (BLRs) constitutes a novel means to probe the…
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Journal Article
Monitoring AGNs with Hβ Asymmetry. IV. First Reverberation Mapping Results of 14 Active Galactic Nuclei
We report first-time reverberation-mapping results for 14 active galactic nuclei (AGNs) from the ongoing Monitoring AGNs with H β Asymmetry campaign (MAHA). These results utilize optical spectra obtained with the Long Slit Spectrograph on the Wyoming Infrared 2.3 m Telescope between 2017 November…
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Journal Article
AGN STORM 2. XII. Ground-based Optical Photometry and Lag Measurements of Mrk 817
We present the ground-based imaging campaign and light curves of Markarian 817 as part of the multiwavelength monitoring program AGN STORM 2. Observations were carried out over 1.4 yr in the uBgVriz filters, with a median cadence of 0.4 day in the g band. Reverberation lags are measured using three…