47 citations · 126 across the 22 of their papers we have counts for
24 papers
The Intermediate-Mass Black Hole Reverberation Mapping Project: Scientific Overview and Sample Characteristics
Hengxiao Guo, Jiancheng Wu, Wenwen Zuo +38
Recent discoveries with the James Webb Space Telescope of massive black holes at high redshift have highlighted fundamental questions about black hole seed formation and the coevol…
X-ray Fourier lag-frequency spectra modulated by stochastic turbulent acceleration in the jets of high-frequency-peaked BL Lac
Guang-Cheng Xiao, Wen Hu, Da-Guo Jiang +4
X-ray interband time lags are key diagnostics of jet physics and are frequently detected in high-frequency peaked BL Lac (HBL) objects at different epochs with various X-ray telesc…
The Intermediate-Mass Black Hole Reverberation Mapping Project: Stable Optical Continuum Lags of an IMBH in the Dwarf Galaxy NGC 4395 Over Years
Yu Pan, Hengxiao Guo, Chenxu Liu +15
NGC 4395 is a nearby dwarf spiral galaxy hosting an active galactic nucleus (AGN) powered by an intermediate-mass black hole (IMBH, --). Re…
A UV to X-Ray View of Soft Excess in Type 1 Active Galactic Nuclei. II. Broadband Correlations
Shi-Jiang Chen, Jun-Xian Wang, Jia-Lai Kang +5
The physical origin of soft X-ray excess (SE) is a long lasting question, with two prevailing theories -- ``warm corona'' and ``ionized reflection'' -- dominating the discussion. I…
Discovery of Repeating Transitions in 16 Changing-look Active Galactic Nuclei
Qian Dong, Zhi-Xiang Zhang, Wei-Min Gu +5
The repeating changing-look active galactic nuclei (RCL AGNs) exhibit multiple appearances and disappearances of broad emission lines (BELs), whose underlying mechanism remains a p…
Baseline-Aware Dependence fitting for DAmping Timescales (BADDAT): A Nearly Unbiased Approach to Constraining Optical Variability Dependence on Physical Properties of Active Galactic Nuclei
Ruisong Xia, Zhen-Yi Cai, Yongquan Xue +7
Active galactic nuclei (AGNs) exhibit stochastic optical variability, commonly characterized by a damped random walk. The damping timescale is of particular interest because it is…
Interband Lag Variability in Active Galactic Nuclei across ZTF Data from Multiple Years
Zhen-Bo Su, Zhen-Yi Cai, Hengxiao Guo +2
Interband lags in the optical continua of active galactic nuclei (AGN) have been observed over years of monitoring, yet their physical origins remain unclear. While variable interb…
A Sandwich Model for Changing-Look AGNs
Qian-Qi Ma, Wei-Min Gu, Zhen-Yi Cai +4
The spectral variability of changing-look active galactic nuclei (CL-AGNs) occurred on timescales of years to tens of years, posing a significant challenge to the standard thin dis…
The Intermediate-Mass Black Hole Reverberation Mapping Project: First Detection of Mid-Infrared Lags in Prototypical IMBHs in NGC 4395 and POX 52
Jingbo Sun, Hengxiao Guo, Wenwen Zuo +25
The search for robust evidence of intermediate-mass black holes (IMBHs) is crucial for understanding black hole seeding process and the formation of supermassive black holes in the…
A UV to X-ray view of soft excess in type 1 AGNs: I. sample selection and spectral profile
Shi-Jiang Chen, Jun-Xian Wang, Jia-Lai Kang +5
A core sample of 59 unobscured type 1 AGNs with simultaneous XMM-Newton X-ray and UV observations is compiled from archive to probe the nature of soft X-ray excess (SE). In the fir…
The Composite Spectral Energy Distribution of Quasars is Surprisingly Universal Since Cosmic Noon
Zhen-Yi Cai
Leveraging the photometric data of the Sloan Digital Sky Survey and the Galaxy Evolution Explorer (GALEX), we construct mean/median spectral energy distributions (SEDs) for unique…
Could the inter-band lag of active galactic nucleus vary randomly?
Zhen-Bo Su, Zhen-Yi Cai, Jun-Xian Wang +18
The inter-band lags among the optical broad-band continua of active galactic nuclei (AGNs) have been intensively explored over the past decade. However, the nature of the lags rema…
Nucleosynthesis contribution of neutrino-dominated accretion flows to the solar neighborhood
Yan-Qing Qi, Tong Liu, Mouyuan Sun +1
The elemental abundances of stars reflect the complex enrichment history of the galaxy. To explore and explain the metal enrichment history of the cosmic environment near our solar…
Unprecedented Continuum Time Delay Variation Phenomenon in an Active Supermassive Black Hole
Shuying Zhou, Mouyuan Sun, Hai-Cheng Feng +12
Resolving the accretion disks and broad line regions (BLRs) of active galactic nuclei (AGNs) can probe the physics behind supermassive black holes (SMBHs) fueling and weigh SMBHs.…
Integrated Study of X-ray Spectrum and Time Lags for HBL Mrk 421 within the Framework of the Multiple-Zone Leptonic Model
Wen Hu, Jia-Lai Kang, Zhen-Yi Cai +3
We present the timing analysis of 10 archived \XMM observations with an exposure of ks of Markarian 421. Mrk 421 is the brightest high-frequency-peaked BL Lac object (HBL) em…
A surprising excess of radio emission in extremely stable quasars: a unique clue to jet launching?
Wen-Yong Kang, Jun-Xian Wang, Zhen-Yi Cai +6
Quasars are generally divided into jetted radio-loud and non-jetted radio-quiet ones, but why only 10% quasars are radio loud has been puzzling for decades. Other than jet-induced-…
A new timescale-mass scaling for the optical variation of active galactic nuclei across the intermediate-mass to supermassive scales
Zhen-Bo Su, Zhen-Yi Cai, Mouyuan Sun +3
Variability of active galactic nuclei (AGNs) has long been servicing as an essential avenue of exploring the accretion physics of black hole (BH). There are two commonly used metho…
Optical Continuum Reverberation Mapping of a Candidate IMBH in a Nearby Seyfert 1 Galaxy
Wenwen Zuo, Hengxiao Guo, Jingbo Sun +25
To investigate the short-term variability and determine the size of the optical continuum emitting region of intermediate-mass black holes (IMBHs), we carried out high-cadence, mul…
Sizes of active galactic nuclei inhomogeneous disks -- large in microlensing, small in reverberation mapping
Guowei Ren, Mouyuan Sun, Jun-Xian Wang +1
Magnetohydrodynamics (MHD) turbulence can drive significant temperature fluctuations in the accretion disk of an active galactic nucleus (AGN). As a result, the disk can be highly…
How long will the quasar UV/optical flickering be damped?
Shuying Zhou, Mouyuan Sun, Zhen-Yi Cai +3
The UV/optical light curves of Active Galactic Nuclei (AGNs) are commonly described by the Damped Random Walk (DRW) model. However, the physical interpretation of the damping times…
Extreme Variability Quasars in Their Various States. II: Spectral Variation Revealed with Multi-epoch Spectra
Wenke Ren, Junxian Wang, Zhenyi Cai +1
We previously built a sample of 14,012 extremely variable quasars (EVQs) based on SDSS and Pan-STARRS1 photometric observations. In this work we present the spectral fitting to the…
How can the optical variation properties of active galactic nuclei be unbiasedly measured?
Xu-Fan Hu, Zhen-Yi Cai, Jun-Xian Wang
The variability of active galactic nuclei (AGNs) is ubiquitous but has not yet been understood. Measuring the optical variation properties of AGNs, such as variation timescale and…
A universal average spectral energy distribution for quasars from optical to extreme ultraviolet
Zhen-Yi Cai, Jun-Xian Wang
The well-known anti-correlation between the optical/ultraviolet (UV) emission line equivalent widths of active galactic nuclei and the continuum luminosity (the so-called Baldwin e…
How far is quasar UV/optical variability from damped random walk at low frequency?
Hengxiao Guo, Junxian Wang, Zhengyi Cai +1
Studies have shown that UV/optical light curves of quasars can be described with the prevalent damped random walk (DRW, also known as Ornstein-Uhlenbeck process) model. A white noi…