A5047974679- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Black Holes and Theoretical Physics
- Astrophysics and Star Formation Studies
- Atmospheric and Environmental Gas Dynamics
- History and Developments in Astronomy
- Calibration and Measurement Techniques
Kavli Institute for Theoretical Sciences
2023-2025
Peking University
2023-2025
Shanghai Astronomical Observatory
2021-2022
Huazhong University of Science and Technology
2021-2022
Abstract Changing-look active galactic nuclei (AGNs) are a special class of AGNs that change their spectral type from 1 to 2 or vice versa. In recent years, number changing-look blazars (CLBs) were also reported, which transition between flat-spectrum radio quasars and BL Lacs. The physical properties CLBs still unclear. Using the mclust R package for Gaussian mixture modeling, we performed clustering analysis sample 105 selected literature. Three kinds found lie in parameter distributions...
Abstract The discovery of changing-look active galactic nuclei (CLAGNs) with a significant change in optical broad emission lines (optical CLAGNs) and/or strong variation line-of-sight column densities (X-ray challenges the orientation-based AGN unification model. We explore mid-infrared (mid-IR) properties for sample 57 CLAGNs and 11 X-ray based on Wide-field Infrared Survey Explorer archive data. find that Eddington-scaled mid-IR luminosities both stay just between those low-luminosity...
Aims. We discovered that the changing-look active galactic nucleus (CLAGN) SDSS J101152.98+544206.4 (J1011+5442 for short) gradually returns to type I state after a short period between 2014 and 2019 in faint 1.9 state. Methods. Motivated by rebrightening optical mid-infrared light curves from ZTF WISE, we obtained new spectroscopic observations with Xinglong 2.16 m, Lijiang 2.4 MMT 6.5 m telescopes 2024. Results. After changing its AGN 1 2003 2015 according repeat spectroscopy Time Domain...
Abstract Changing-look active galactic nuclei (CLAGNs) are known to change their spectral type between 1 and 2 (changing-state) or absorption Compton-thick Compton-thin (changing-obscuration) on timescales of years less. The physical mechanism possible connection the two types CLAGNs still unclear. We explore evolution broadband X-ray spectra from Nuclear Spectroscopic Telescope Array (NuSTAR ) column density in five with moderate inclination viewing angles, which have shown significant...
The wide survey of the Chinese Space Station Telescope (CSST) will observe a large field 17,500 $\text{deg}^2$. GU, GV, and GI grism observations CSST cover wavelength range from 2550 to 10000\r{A} at resolution $R\sim 200$ depth about 22 AB magnitude for continuum. In this paper, we present pipeline identify quasars measure their physical properties with mock data. We simulate raw images extract one-dimensional spectra quasars, galaxies, stars r-band magnitudes $18<\text{m}_{\text{r}}<22$...
Abstract The wide survey of the Chinese Space Station Telescope (CSST) will observe a large field 17,500 deg 2 . GU, GV, and GI grism observations CSST cover wavelength range from 2550 to 10000 Å at resolution R ∼ 200 depth about 22 AB magnitude for continuum. In this paper, we present pipeline identify quasars measure their physical properties with mock data. We simulate raw images extract one-dimensional spectra quasars, galaxies, stars r -band magnitudes 18 < m using Cycle 6 simulation...
Abstract Quasars behind the Galactic plane (GPQs) are excellent tracers to probe chemistry and kinematics of interstellar/intergalactic medium Milky Way along sight lines via absorption line spectroscopy. Moreover, quasars located at low latitudes will fill gap in spatial distribution known near plane, can be used construct an astrometric reference frame for accurate measurements proper motions stars, substructures Way. We started a survey background latitude region with LAMOST phase II...
Abstract The hydrogen Balmer decrement (e.g., H α /H β ) is widely adopted as an indicator of the internal reddening active galactic nuclei (AGNs). This challenged by some low-luminosity AGNs and changing-look (CLAGNs), which have steep but without strong evidence for absorption. We compile a sample normal CLAGNs with wider distribution bolometric Eddington ratio ( λ Edd = L bol / find negative correlation between , suggests that also accretion-rate dependent. further explore based on...
The physical mechanism for triggering the changing-look phenomenon in active galactic nuclei (AGNs) is still unclear. We explore this issue based on multi-wavelength spectral and flux variations a AGN Mrk~1018 with long-term observations X-ray, optical/ultraviolet(UV), radio bands. Both optical X-ray emission experience rapid decay phase during 2010--2015, where re-flare appears optical/UV find time lag of $\sim 20 $ days behind type 1.9 phase. 5 GHz decreases by 20$\% 2016--2017. both...
Changing-look active galactic nuclei (CLAGNs) show the disappearance and reappearance of broad emission lines in a few years, which challenges orientation-based AGN unification model. We reduce X-ray data for five well-studied CLAGNs that strong change past several decades. find photon index, $\Gamma$, Eddington-scaled luminosity, $L_{\rm 2-10 keV}/L_{\rm Edd}$, normally follow negative positive correlations when Eddington ratio is lower higher than critical value $\sim 10^{-3}$. observed...
Abstract Weak-line quasars (WLQs) are a notable group of active galactic nuclei (AGNs) that show unusually weak UV lines even though their optical-UV continuum shapes similar to those typical quasars. The physical mechanism for WLQs is an unsolved puzzle in the AGN unified model. We explore properties emission by performing extensive photoionization calculations based on Cloudy simulations with different spectral energy distributions (SEDs) AGNs. continua built from several observational...
ABSTRACT We explore the timing and spectral properties of GRS 1915+105 based on X-ray observations NICER Insight-HXMT during long outburst from 2017 to 2021. find a new class variability in rising stage that differs formerly reported patterns light curves. This pattern, which we name ψ, is characterized by several periodic mini pulses superposed another longer pulse. The periods are ∼130 ∼10 s for main pulses, respectively, analysis power spectrum density step-wise filter correlation (SFC),...
Aims. We reported the discovery that a changing-look AGN SDSS J101152.98+544206.4 (J1011+5442 for short) gradually returns to type 1 state after short period between 2014 and 2019 in faint 1.9 state. Methods. Motivated by rebrightening optical mid-infrared light curves from ZTF WISE, we obtained new spectroscopic observations Xinglong 2.16-m, Lijiang 2.4-m, MMT 6.5-m telescopes 2024. Results. After changing 2003 2015 based on repeat spectroscopy Time Domain Spectroscopic Survey, J1011+5442...
We explore the timing and spectral properties of GRS 1915+105 based on X-ray observations NICER Insight-HXMT during long outburst from 2017 to 2021. find a new class variability in rising stage that differs formerly reported patterns light curves. This pattern, which we name $\psi$, is characterized by several periodic mini pulses superposed another longer pulse. The periods are around $\sim$130 seconds $\sim$10 for main respectively analysis power spectrum density (PSD) step-wise filter...