Yongyun Chen
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View article: The Relation between the Optical Variability Timescale, Magnetic Field of Jets, and Black Hole Spin in Active Galactic Nuclei
The Relation between the Optical Variability Timescale, Magnetic Field of Jets, and Black Hole Spin in Active Galactic Nuclei Open
We investigate the relationship among the jet magnetic field, black hole spin, black hole mass, Eddington ratio, and optical variability timescales in jetted active galactic nuclei (AGNs). By fitting a damped random walk (DRW) model to the…
View article: Identifying Compton-thick Active Galactic Nuclei with a Machine Learning Algorithm in Chandra Deep Field-South
Identifying Compton-thick Active Galactic Nuclei with a Machine Learning Algorithm in Chandra Deep Field-South Open
Compton-thick active galactic nuclei (CT-AGNs), which are defined by column density N H ≥ 1.5 × 10 24 cm −2 , emit feeble X-ray radiation, even undetectable by X-ray instruments. Despite this, the X-ray emissions from CT-AGNs are believed …
View article: A Characteristic Optical Variability Timescale in Jetted Active Galactic Nuclei: A Large Gamma-Ray Emission Sample
A Characteristic Optical Variability Timescale in Jetted Active Galactic Nuclei: A Large Gamma-Ray Emission Sample Open
The variability mechanisms from jetted active galactic nuclei (AGNs) are still under debate. Here, the damped random walk (DRW) model, implemented through Gaussian processes (GPs), is used to fit the Zwicky Transient Facility long-term opt…
View article: Observatory Science with eXTP
Observatory Science with eXTP Open
Scheduled for launch in 2030, the enhanced X-ray Timing and Polarization (eXTP) telescope is a Chinese space-based mission aimed at studying extreme conditions and phenomena in astrophysics. eXTP will feature three main payloads: Spectrosc…
View article: Accretion properties and jet mechanisms for the low-excitation radio galaxies
Accretion properties and jet mechanisms for the low-excitation radio galaxies Open
Context. Radio galaxies (RGs) are a subclass of active galactic nuclei, which are suggested to be the parent populations of blazars. Based on morphologies and radio powers, RGs can be classified as Fanaroff-Riley type 0 (FR 0s), I (FR Is),…
View article: The relation between black hole spin, star formation rate, and black hole mass for supermassive black holes
The relation between black hole spin, star formation rate, and black hole mass for supermassive black holes Open
Both theoretical models and observational evidence indicate that jets and/or outflows driven by central active supermassive black holes exert a significant feedback effect on the overall properties of their host galaxies. Theoretical model…
View article: Observational evidence for a correlation between the magnetic field of jets and star formation rate in host galaxies
Observational evidence for a correlation between the magnetic field of jets and star formation rate in host galaxies Open
Accretion supermassive black holes in the center of active galaxies usually produce ``jets''-collimated bipolar outflows of relativistic particles. Magnetic fields near the black hole event horizon may play a crucial role in the formation …
View article: The relation between black hole spin and star formation in massive star-forming galaxies
The relation between black hole spin and star formation in massive star-forming galaxies Open
It has always been believed that feedback from active galactic nuclei (AGN) has an important impact on star formation in massive galaxies. Black hole spin is an important physical parameter of AGN. We use a large sample of massive star-for…
View article: The relation between black hole spin and star formation in massive star-forming galaxies
The relation between black hole spin and star formation in massive star-forming galaxies Open
It has always been believed that feedback from active galactic nuclei (AGNs) has an important impact on star formation in massive galaxies. Black hole spin is an important physical parameter of AGN. We use a large sample of massive star-fo…
View article: Identifying Compton-thick AGNs in the COSMOS. I. Among X-ray AGNs with Low Photon Counts
Identifying Compton-thick AGNs in the COSMOS. I. Among X-ray AGNs with Low Photon Counts Open
Compton-thick active galactic nuclei (CT-AGNs), characterized by a significant absorption with column densities of $\mathrm{N_H}\geqslant 1.5\times 10^{24} \ \mathrm{cm}^{-2}$, emit feeble X-ray radiation and are even undetectable by X-ray…
View article: Identifying Compton-thick AGNs in the COSMOS
Identifying Compton-thick AGNs in the COSMOS Open
Context. Compton-thick active galactic nuclei (CT-AGNs), characterized by a significant absorption with column densities of N H ≥ 1.5 × 10 24 cm −2 , emit feeble X-ray radiation and are even undetectable by X-ray instruments, making them d…
View article: Observational Evidence for a Correlation between the Magnetic Field of Jets and Star Formation Rate in Host Galaxies
Observational Evidence for a Correlation between the Magnetic Field of Jets and Star Formation Rate in Host Galaxies Open
Accretion supermassive black holes in the center of active galaxies usually produce “jet”-collimated bipolar outflows of relativistic particles. Magnetic fields near the black hole event horizon may play a crucial role in the formation of …
View article: The Study of Jet Formation Mechanism in Fermi Blazars
The Study of Jet Formation Mechanism in Fermi Blazars Open
The origin of jet launching mainly comes from two mechanisms: the Blandford–Znajek (BZ) mechanism and the Blandford–Payne (BP) mechanism. However, it is in debate which one is dominating in blazars. In this work, we used a sample of 937 Fe…
View article: Jets, accretion and spin in supermassive black holes
Jets, accretion and spin in supermassive black holes Open
The theoretical model suggests that relativistic jets of AGN rely on the black hole spin and/or accretion. We study the relationship between jet, accretion, and spin using supermassive black hole samples with reliable spin of black holes. …
View article: General Physical Properties of Fermi Blazars
General Physical Properties of Fermi Blazars Open
We study the general physical properties of Fermi blazars using the Fermi fourth source catalog data (4FGL-DR2). The quasi-simultaneous multiwavelength data of Fermi blazars are fitted by using the one-zone leptonic model to obtain some ph…
View article: General Physical Properties of Fermi blazars
General Physical Properties of Fermi blazars Open
We study the general physical properties of Fermi blazars using the Fermi fourth source catalog data (4FGL-DR2). The quasi-simultaneous multiwavelength data of Fermi blazar are fitted by using the one-zone leptonic model to obtain some phy…
View article: General Physical Properties of Gamma-Ray-emitting Radio Galaxies
General Physical Properties of Gamma-Ray-emitting Radio Galaxies Open
We study the radio galaxies with known redshift detected by the Fermi satellite after 10 years of data (4FGL-DR2). We use a one-zone leptonic model to fit the quasi-simultaneous multiwavelength data of these radio galaxies and study the di…
View article: General Physical Properties of Gamma-Ray-emitting Radio Galaxies
General Physical Properties of Gamma-Ray-emitting Radio Galaxies Open
We study the radio galaxies with known redshifts detected by the Fermi satellite after 10 yr of data (4FGL-DR2). We use a one-zone leptonic model to fit the quasi-simultaneous multiwavelength data of these radio galaxies and study the dist…
View article: A Special State Transition in the Blazar OT 081: Implication for the Unified State Transition Paradigm of Different-scale Black Hole Systems
A Special State Transition in the Blazar OT 081: Implication for the Unified State Transition Paradigm of Different-scale Black Hole Systems Open
Exploring the similar behavior of black hole systems with different scales will provide insight into the unified physical laws of black hole systems. Here, we report a special spectral state transition process in blazar OT 081, which is dr…
View article: Curvature of the Spectral Energy Distribution, Compton Dominance, and Synchrotron Peak Frequency in Jetted Active Galactic Nuclei
Curvature of the Spectral Energy Distribution, Compton Dominance, and Synchrotron Peak Frequency in Jetted Active Galactic Nuclei Open
We collect a large sample with a reliable redshift detected by the Fermi satellite after 10 yr of data (4FGL-DR2), including blazars, gamma-ray narrow-line Seyfert 1 galaxies ( γ NLS1s), and radio galaxies. The spectral energy distribution…
View article: Evidence for the astrophysics of rotational energy extraction from a supermassive black hole
Evidence for the astrophysics of rotational energy extraction from a supermassive black hole Open
Theoretical models predict that the power of relativistic jets of active galactic nuclei arises from the spin of the central supermassive black holes. In the Blandford-Znajek mechanism{\cite{blandford77}}, if relativistic jets are powered …
View article: Multiwavelength Analysis of a Nearby Heavily Obscured AGN in NGC 449
Multiwavelength Analysis of a Nearby Heavily Obscured AGN in NGC 449 Open
We presented the multiwavelength analysis of a heavily obscured active galactic nucleus (AGN) in NGC 449. We first constructed a broadband X-ray spectrum using the latest NuSTAR and XMM-Newton data. Its column density ($\simeq 10^{24} \rm{…
View article: The Variability of the Narrow-line Seyfert 1 Galaxies from the Pan-STARRS’s View
The Variability of the Narrow-line Seyfert 1 Galaxies from the Pan-STARRS’s View Open
By means of the data sets from the Pan-STARRS1 survey, we have systematically examined the relationship between the variability characteristics and the physical parameters of the largest NLS1 galaxy sample up to now. The results are summar…
View article: The Powers of Relativistic Jets Depend on the Spin of Accreting Supermassive Black Holes
The Powers of Relativistic Jets Depend on the Spin of Accreting Supermassive Black Holes Open
Theoretical models show that the power of relativistic jets of active galactic nuclei depends on the spin and mass of the central supermassive black holes, as well as the accretion. Here we report an analysis of archival observations of a …
View article: In-depth investigation of the physical origin of the soft X-ray excess in PG 1448+273
In-depth investigation of the physical origin of the soft X-ray excess in PG 1448+273 Open
We present systematic X-ray spectral and variability analyses for the narrow-line Seyfert 1 galaxy (NLsy1), PG 1448+273, using the data from two long-exposure XMM-Newton observations of the source in the different flux states. These X-ray …
View article: From the Fermi Blazar Sequence to the Relation between Fermi Blazars and γ-Ray Narrow-line Seyfert 1 Galaxies
From the Fermi Blazar Sequence to the Relation between Fermi Blazars and γ-Ray Narrow-line Seyfert 1 Galaxies Open
We use the third catalog of blazars detected by Fermi/LAT (3LAC) and γ -ray narrow-line Seyfert 1 Galaxies ( γ -NLSy1s) to study the blazar sequence and relationship between them. Our results are as follows. (i) There is a weak anticorrela…
View article: Physical properties of the CDFS X-ray sources through fitting spectral energy distributions
Physical properties of the CDFS X-ray sources through fitting spectral energy distributions Open
The physical parameters of galaxies and/or active galactic nucleus (AGNs) can be derived by fitting their multiband spectral energy distributions (SEDs). By using cigale code, we perform multiband SED fitting (from ultraviolet to infrared)…
View article: What drives the velocity dispersion of ionized gas in star-forming galaxies?
What drives the velocity dispersion of ionized gas in star-forming galaxies? Open
We analyse the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with sta…
View article: What drives the velocity dispersion of ionized gas in star-forming galaxies?
What drives the velocity dispersion of ionized gas in star-forming galaxies? Open
We analyze the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with sta…
View article: Physical properties variation across the green valley for local galaxies
Physical properties variation across the green valley for local galaxies Open
We have selected a sample of nearby galaxies from Sloan Digital Sky Survey Data Release 7 (SDSS DR7) to investigate the physical properties variation from blue cloud to green valley to red sequence. The sample is limited in a narrow range …