Publications (132)
Simulating the galaxy cluster "El Gordo": gas motion, kinetic Sunyaev-Zel'dovich signal, and X-ray line features
Congyao Zhang, Qingjuan Yu, Youjun Lu
The massive galaxy cluster "El Gordo" (ACT-CL J0102--4915) is a rare merging system with a high collision speed suggested by multi-wavelength observations and the theoretical model…
Black hole and cosmos with multiple horizons and multiple singularities in vector-tensor theories
Changjun Gao, Youjun Lu, Shuang Yu +1
A stationary and spherically symmetric black hole (For example, Reissner-Nordstrom black hole or Kerr-Newman black hole) has at most one singularity and two horizons. One horizon i…
Searching for kilonova with the SiTian prototype telescope
Zhirui Li, Hongrui Gu, Yongkang Sun +3
We simulate the optical searching of gravitational-wave electromagnetic counterpart of the binary neutron star (BNS) merger event (i.e., a kilonova) using the ground based {\it SiT…
Possible Evidence for a Truncated Thin Disk in Seyfert 1 Galaxy NGC4593
Youjun Lu, Tinggui Wang
We compile the multi-band spectral energy distribution (SED) of Seyfert 1 galaxy NGC4593, and investigate its optical-to-ultraviolet (OUV) continuum and iron Kαline profile. No st…
Enhanced Localization of Dark Lensed Gravitational Wave Events Enables Host Galaxy Identification and Precise Cosmological Inference
Zhiwei Chen, Qingjuan Yu, Youjun Lu +1
Lensed gravitational wave (GW) events are expected to be powerful new probes of cosmology, contingent on redshift measurement by electromagnetic observations. Host galaxy identific…
Testing the relativistic Doppler boost hypothesis for supermassive binary black holes candidates via broad emission line profiles
Zihao Song, Junqiang Ge, Youjun Lu +1
Optical periodicity QSOs found by transient surveys are suggested to be sub-parsec supermassive binary black holes (BBHs). An intriguing interpretation for the periodicity of some…
On networks of space-based gravitational-wave detectors
Rong-Gen Cai, Zong-Kuan Guo, Bin Hu +7
The space-based laser interferometers, LISA, Taiji and TianQin, are targeting to observe milliHz gravitational waves (GWs) in the 2030s. The joint observations from multiple space-…
Prospects for Time-Domain and Multi-Messenger Science with eXTP
Shu-Xu Yi, Wen Zhao, Ren-Xin Xu +75
In this new era of time-domain and multi-messenger astronomy, various new transients and new phenomena are constantly being discovered thanks to the rapid advances in observations,…
Investigating the co-evolution of massive black holes in dual active galactic nuclei and their host galaxies via galaxy merger simulations
Chao Yang, Junqiang Ge, Youjun Lu
Major galaxy mergers can trigger nuclear activities and are responsible for high-luminosity quasi-stellar objects /active galactic nuclei (QSOs/AGNs). In certain circumstances, suc…
Constraining the origin of stellar binary black hole mergers by detections of their lensed host galaxies and gravitational wave signals
Zhiwei Chen, Youjun Lu, Yuetong Zhao
A significant number of stellar binary black hole (sBBH) mergers may be lensed and detected by the third generation gravitational wave (GW) detectors. Their lensed host galaxies ma…
Multi-messenger Detection Rates and distributions of Binary Neutron Star Mergers and Their Cosmological Implications
Jiming Yu, Haoran Song, Shunke Ai +6
The gravitational-wave (GW) events, produced by the coalescence of binary neutron-stars (BNS), can be treated as the standard sirens to probe the expansion history of the Universe,…
A high-velocity star recently ejected by an intermediate-mass black hole in M15
Yang Huang, Qingzheng Li, Jifeng Liu +4
The existence of intermediate-mass black holes (IMBHs) is crucial for understanding various astrophysical phenomena, yet their existence remains elusive, except for the LIGO-Virgo…
The cosmic evolution of massive black holes and galaxy spheroids: global constraints at redshift z<~1.2
Xiaoxia Zhang, Youjun Lu, Qingjuan Yu
We study the observational constraints on the cosmic evolution of the relationships between the massive black hole (MBH) mass (M_bh) and the stellar mass (M^*_sph; or velocity disp…
Convergence and Efficiency of Different Methods to Compute the Diffraction Integral for Gravitational Lensing of Gravitational Waves
Xiao Guo, Youjun Lu
Wave optics may need to be considered when studying the lensed waveforms of gravitational waves (GWs). However, the computation of the diffraction integral (amplification factor) i…
X-ray Eclipses of Active Galactic Nuclei
Fupeng Zhang, Qingjuan Yu, Youjun Lu
X-ray variation is a ubiquitous feature of active galactic nuclei (AGNs), however, its origin is not well understood. In this paper, we show that the X-ray flux variations in some…
Effect of accreting tidally disrupted stars on the spin evolution of black holes
Xiaoxia Zhang, Youjun Lu, Zhu Liu
Accretion of tidally disrupted stars (TDSs) is expected to contribute significantly to the growth of massive black holes (MBHs) with mass in galactic centers.…
The spatial and velocity distributions of hypervelocity stars
Fupeng Zhang, Youjun Lu, Qingjuan Yu
Hypervelocity stars (HVSs) found in the Galactic halo are probably the dynamical products of interactions between (binary) stars and the massive black hole(s) (MBH) in the Galactic…
21cm Signal Recovery via the Robust Principle Component Analysis
Shifan Zuo, Xuelei Chen, Reza Ansari +1
The redshifted 21~cm signal from neutral hydrogen (HI) is potentially a very powerful probe for cosmology, but a difficulty in its observation is that it is much weaker than foregr…
Gravitational-wave standard sirens and application in cosmology
Wen Zhao, Liang-Gui Zhu, Youjun Lu
The discovery of the gravitational-wave event GW170817 from a binary neutron star merger, together with its multi-wavelength electromagnetic counterparts, marks the beginning of th…
A probable Milli-Parsec Supermassive Binary Black Hole in the Nearest Quasar Mrk 231
Chang-Shuo Yan, Youjun Lu, Xinyu Dai +1
Supermassive binary black holes (BBHs) are unavoidable products of galaxy mergers and are expected to exist in the cores of many quasars. Great effort has been made during the past…
Radiative Efficiency of Disk Accretion in Individual SDSS QSOs
Shumei Wu, Youjun Lu, Fupeng Zhang +1
We estimate the radiative efficiency (epsilon) of individual type 1 SDSS QSOs by using their bolometric luminosities (L_{bol}) and accretion rates (\dot{M}_{\bullet,acc}), which ma…
A Comprehensive Study of 2 000 Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey: I. The Sample
Hongyan Zhou, Tinggui Wang, Weimin Yuan +4
This is the first paper in a series dedicated to the study of the emission-line and continuum properties of narrow line Seyfert 1 galaxies (NLS1s). We carried out a systematic sear…
Wind-powered ultraluminous X-ray sources
Grzegorz Wiktorowicz, Jean-Pierre Lasota, Krzysztof Belczynski +3
Although ultra-luminous X-ray sources (ULX) are important for astrophysics due to their extreme apparent super-Eddington luminosities, their nature is still poorly known. Theoretic…
The effects of relativistic bulk motion of X-ray flares in the corona on the iron Kalpha line in Seyfert 1 galaxies
Youjun Lu, Qingjuan Yu
We study the effects of the bulk motion of X-ray flares on the shape and equivalent width of the iron Kalpha line from an untruncated cold disk around a Kerr black hole using fully…
Recovering stellar population parameters via different population models and stellar libraries
Junqiang Ge, Shude Mao, Youjun Lu +2
Three basic ingredients are required to generate a simple stellar population (SSP) library, i.e., an initial mass function (IMF), a stellar evolution model/isochrones, and an empir…
Hydrodynamical Simulations of the Triggering of Nuclear Activities by Minor Mergers of Galaxies
Chao Yang, Junqiang Ge, Youjun Lu
Major mergers of galaxies are considered to be an efficient way to trigger Active Galactic Nuclei and are thought to be responsible for the phenomenon of quasars. This has however…
The diverse morphology of gravitational wave signals from merging neutron-star white-dwarf binaries
Shenghua Yu, Youjun Lu, C. Simon Jeffery +6
In sufficiently compact neutron star-white dwarf (NSWD) binary systems, orbital decay means the white dwarf eventually fills its shrinking Roche lobe, initiating a phase of mass tr…
A Baryonic Effect on the Merger Timescale of Galaxy Clusters
Congyao Zhang, Qingjuan Yu, Youjun Lu
Accurate estimation of the merger timescale of galaxy clusters is important to understand the cluster merger process and further the formation and evolution of the large-scale stru…
On the Mean Radiative Efficiency of Accreting Massive Black Holes in AGNs And QSOs
Xiaoxia Zhang, Youjun Lu
Radiative efficiency is an important physical parameter that describes the fraction of accretion material converted to radiative energy for accretion onto massive black holes (MBHs…
On using the counting method to constrain the anisotropy of kilonova radiation
Siqi Zhang, Furen Deng, Youjun Lu
A large number of binary neutron star (BNS) mergers are expected to be detected by gravitational wave (GW) detectors and the electromagnetic (EM) counterparts (e.g., kilonovae) of…
On Dark Gravitational Wave Standard Sirens as Cosmological Inference and Forecasting the Constraint on Hubble Constant using Binary Black Holes Detected by Deci-hertz Observatory
Ju Chen, Changshuo Yan, Youjun Lu +2
Gravitational wave (GW) signals from compact binary coalescences can be used as standard sirens to constrain cosmological parameters if their redshift can be measured independently…
The correlations of stellar tidal disruption rates with properties of massive black holes and their host galaxies
Yunfeng Chen, Qingjuan Yu, Youjun Lu
Stars can be either disrupted as tidal disruption events (TDEs) or swallowed as a whole by massive black holes (MBHs) at galactic centers when they approach sufficiently close to t…
Prospect for Detection of Strongly Lensed Multi-messenger Signals of Binary Neutron Star Mergers
Zhiwei Chen, Youjun Lu, Changwen Zeng
The gravitational lensing of multi-messenger signals from binary neutron star mergers (BNSs), including gravitational waves (GWs), short Gamma-Ray bursts (sGRBs), kilonovae, and af…
Formation Channels of Gravitationally Resolvable Double White Dwarf Binaries Inside Globular Clusters
Lucas Hellström, MirosÅaw Giersz, Abbas Askar +6
Current gravitational wave detectors are sensitive to coalescing black holes and neutron stars. However, double white dwarfs (DWDs) have long been recognized as promising sources o…
Broad-line region configuration of the supermassive binary black hole candidate PG1302-102 in the relativistic Doppler boosting scenario
Zihao Song, Junqiang Ge, Youjun Lu +2
PG1302-102 is thought to be a supermassive binary black hole (BBH) system according to the periodical variations of its optical and UV photometry, which may be interpreted as being…
Constraining the Yukawa Gravity with Post Newtonian Approximation using S-star Orbits around the Supermassive Black Hole in our Galactic Center
Yuan Tan, Youjun Lu
A number of modified gravity theories (e.g., -gravity) lead to a Yukawa-like metric in the weak field limit which can be described by two Yukawa parameters, i.e., the strengt…
On the Power to Constrain the Accretion History of Massive Black Holes via Spin Measurements by Upcoming X-Ray Telescopes
Xiaoxia Zhang, Youjun Lu, Dandan Wang +1
The spin distribution of massive black holes (MBHs) contains rich information on their assembly history. However, only limited information can be extracted from currently available…
Diffractive lensing of nano-Hertz gravitational waves emitted from supermassive binary black holes by intervening galaxies
Hao Ma, Youjun Lu, Zhiwei Chen +1
Pulsar timing array (PTA) experiments are expected to detect nano-Hertz gravitational waves (GWs) emitted from individual inspiralling supermassive binary black holes (SMBBHs). The…
Evidence for higher black hole spin in radio-loud quasars
Andreas Schulze, Chris Done, Youjun Lu +2
One of the major unsolved questions on the understanding of the AGN population is the origin of the dichotomy between radio-quiet and radio-loud quasars. The most promising explana…
Multiwavelength periodic microlensing signatures of macrolensed supermassive binary black holes
Changshuo Yan, Youjun Lu
The microlensing of lensed quasars presents a promising avenue for understanding the structure of accretion disks around supermassive binary black holes (SMBBHs). We investigated t…
Hypervelocity binary stars: smoking gun of massive binary black holes
Youjun Lu, Qingjuan Yu, D. N. C. Lin
The hypervelocity stars recently found in the Galactic halo are expelled from the Galactic center through interactions between binary stars and the central massive black hole or be…
Multiband gravitational wave observations of stellar binary black holes at the low to middle and high frequencies
Yuetong Zhao, Youjun Lu, Changshuo Yan +2
The ground-based gravitational wave (GW) observatories discover a population of merging stellar binary black holes (BBHs), which are promising targets for multiband observations by…
Swift Monitoring Observations of Mrk 231: Detection of Ultraviolet Variability
Lilan Yang, Xinyu Dai, Youjun Lu +2
We analyze 168 Swift monitoring observations of the nearest broad absorption line quasar Mrk 231 in the UV and X-ray bands, where we detect significant variability in the UV ($\sim…
Reply to Comment on "A slightly oblate dark matter halo revealed by a retrograde precessing Galactic disk warp"
Yang Huang, Qikang Feng, Tigran Khachaturyants +7
In this reply, we present a comprehensive analysis addressing the concerns raised by Dehnen et al. (2024) regarding our recent measurement of the disk warp precession using the `mo…
Fe K_alpha line: A tool to probe massive binary black holes in Active Galactic Nuclei?
Qingjuan Yu, Youjun Lu
Hierarchical mergers of galaxies can form binary black holes (BBHs) since many or most galaxies have central massive black holes (BHs). It is possible that some BBHs exist in activ…
Gravitational lensing of gravitational waves: A statistical perspective
Shun-Sheng Li, Shude Mao, Yuetong Zhao +1
In this paper, we study the strong gravitational lensing of gravitational waves (GWs) from a statistical perspective, with particular focus on the high frequency GWs from stellar b…
Constraining the origin of the nanohertz gravitational-wave background by pulsar timing array observations of both the background and individual supermassive binary black holes
Yunfeng Chen, Qingjuan Yu, Youjun Lu
The gravitational waves (GWs) from supermassive binary black holes (BBHs) are long sought by pulsar timing array experiments (PTAs), in the forms of both a stochastic GW background…
On the Cosmic Variance of the Merger Rate Density of Binary Neutron Stars
Zhiwei Chen, Youjun Lu, Jie Wang +3
The cosmic variance on the star formation history may lead to bias to the merger rate density estimation of binary neutron star (BNS) mergers by the compact binary population synth…
The relationship between the X-ray variability and the central black hole mass
Youjun Lu, Qingjuan Yu
We assembled a sample of Seyfert 1 galaxies, QSOs and Low-Luminosity Active Galactic Nuclei (LLAGNs) observed by ASCA, whose central black hole masses have been measured. We found…
Non-interacting black hole binaries with Gaia and LAMOST
Grzegorz Wiktorowicz, Youjun Lu, Åukasz Wyrzykowski +4
Until recently, black holes (BHs) could be discovered only through accretion from other stars in X-ray binaries, or in merging double compact objects. Improvements in astrometric a…
Systematic Search for Electromagnetic Counterparts to the Binary Neutron Star Merger Candidate GW231109_235456
Zhirui Li, Zhiwei Chen, Yang Huang +2
In this letter, we present a systematic search for the electromagnetic counterparts of binary neutron star (BNS) merger candidate GW231109_235456 by examining all transients report…
Probing baryonic processes and gastrophysics in the formation of the Milky Way dwarf satellites: I. metallicity distribution properties
Jun Hou, Qingjuan Yu, Youjun Lu
In this paper, we study the chemical properties of the stars in the dwarf satellites around the MW-like host galaxies, and explore the possible effects of several baryonic processe…
Limiting the Yukawa Gravity through the Black Hole Shadows of Sgr A* and M87*
Yuan Tan, Youjun Lu, Kunyu Song
Recently, the \textit{EHT} collaboration unveiled the shadow images of the supermassive black hole (SMBH) M87* and Sgr A*, with angular radii of \,as and \,…
On the spatial distribution and the origin of hypervelocity stars
Youjun Lu, Fupeng Zhang, Qingjuan Yu
Hypervelocity stars (HVSs) escaping away from the Galactic halo are dynamical products of interactions of stars with the massive black hole(s) (MBH) in the Galactic Center (GC). Th…
Constraining Common Envelope Evolution in Binary Neutron Star Formation with Combined Galactic and Gravitational-Wave Observations
Zhiwei Chen, Jihui Zhang, Youjun Lu +2
Binary neutron stars (BNSs) are among the most interesting sources for multimessenger studies. A number of recently discovered BNSs in the Milky Way by radio telescopes have added…
A slightly oblate dark matter halo revealed by a retrograde precessing Galactic disk warp
Yang Huang, Qikang Feng, Tigran Khachaturyants +7
The shape of the dark matter (DM) halo is key to understanding the hierarchical formation of the Galaxy. Despite extensive efforts in recent decades, however, its shape remains a m…
Probing the precession of the inner accretion disk in Cygnus X-1
Diego F. Torres, Gustavo E. Romero, Xavier Barcons +1
We show that changes in the orientation of the inner accretion disk of Cygnus X-1 affect the shape of the broad Fe K emission line emitted from this object, in such a way that…
On Detecting Stellar Binary Black Holes via the LISA-Taiji Network
Ju Chen, Changshuo Yan, Youjun Lu +2
The detection of gravitational waves (GWs) by ground-based laser interferometer GW observatories (LIGO/Virgo) reveals a population of stellar binary black holes (sBBHs) with (total…
On the detection of the electromagnetic counterparts from lensed gravitational wave events by binary neutron star mergers
Hao Ma, Youjun Lu, Xiao Guo +2
Future ground-based gravitational wave (GW) detectors, i.e., Einstein telescope (ET) and Cosmic Explorer (CE), are expected to detect a significant number of lensed binary neutron…
The Formation of a 70 Msun Black Hole at High Metallicity
K. Belczynski, R. Hirschi, E. A. Kaiser +7
A 70Msun BH was discovered in Milky Way disk in a long period and almost circular detached binary system (LB-1) with a high metallicity 8Msun B star companion. Current consensus on…
Cosmic distributions of stellar tidal disruptions by massive black holes at galactic centers
Yunfeng Chen, Qingjuan Yu, Youjun Lu
Stars can be consumed (either tidally disrupted or swallowed whole) by massive black holes (MBHs) at galactic centers when they move into the vicinity of the MBHs. In this study, w…
The luminosity functions of kilonovae from binary neutron star mergers under different equation of states
Chunyang Zhao, Youjun Lu, Qingbo Chu +1
Kilonovae produced by mergers of binary neutron stars (BNSs) are important transient events to be detected by time domain surveys with the alerts from the ground-based gravitationa…
On Detecting Nearby Nano-Hertz Gravitational Wave Sources via Pulsar Timing Arrays
Xiao Guo, Youjun Lu, Qingjuan Yu
Massive binary black holes (MBBHs) in nearby galactic centers, if any, may be nano-Hertz gravitational wave (GW) sources for pulsar timing arrays (PTAs) to detect. Normally the obj…
Offsets between the X-ray and the Sunyaev-Zel'dovich-effect peaks in merging galaxy clusters and their cosmological implications
Congyao Zhang, Qingjuan Yu, Youjun Lu
Observations reveal that the peaks of the X-ray map and the Sunyaev-Zel'dovich (SZ) effect map of some galaxy clusters are offset from each other. In this paper, we perform a set o…
Constraining the Binarity of Massive Black Holes in the Galactic Center and Some Nearby Galaxies via Pulsar Timing Array Observations of Gravitational Waves
Xiao Guo, Qingjuan Yu, Youjun Lu
Massive black holes (MBHs) exist in the Galactic center (GC) and other nearby galactic nuclei. As natural outcome of galaxy mergers, some MBHs may have a black hole (BH) companion.…
Inspiraling streams of enriched gas observed around a massive galaxy 11 billion years ago
Shiwu Zhang, Zheng Cai, Dandan Xu +19
Stars form in galaxies, from gas that has been accreted from the intergalactic medium. Simulations have shown that recycling of gas-the reaccretion of gas that was previously eject…
The Age-Redshift Relation For Luminous Red Galaxies Obtained From the Full Spectrum Fitting and Its Cosmological Implications
Gaochao Liu, Youjun Lu, Xuelei Chen +3
The relative age of galaxies at different redshifts can be used to infer the Hubble parameter and put constraints on cosmological models. We select 23,883 quiescent luminous red ga…
Relativistic Fe K Line Revealed in the Composite X-ray Spectrum of Narrow Line Seyfert 1 Galaxies --- do their black holes have averagely low or intermediate spins?
Zhu Liu, Weimin Yuan, Youjun Lu +1
While a broad profile of the Fe K emission line is frequently found in the X-ray spectra of typical Seyfert galaxies, the situation is unclear in the case of Narrow Line Seyfer…
On probing the properties of QSOs through their proximity effects on the intergalactic medium
Youjun Lu, Qingjuan Yu
The proximity effect (PE) of QSOs is believed to be useful in constraining the QSO lifetime. Observations on the PE so far, however, give apparently contradictory results -- some a…
Investigating the existence of gravitomagnetic monopole in M87*
M. Ghasemi-Nodehi, Chandrachur Chakraborty, Qingjuan Yu +1
We examine the possibility for the existence of gravitomagnetic monopole () in M87* by using the results obtained from its first Event Horizon Telescope image. By numerically…
An equal mass ratio supermassive binary black holes in Q J0158-4325 with periodic microlensing signature?
Changshuo Yan, Youjun Lu, Junqian Ge +1
This study aims to test whether a supermassive binary black hole (SMBBH) system with a triple-disk accretion structure can explain the observed 173-day periodic microlensing…
Multiband gravitational wave observations of eccentric escaping binary black holes from globular clusters
Yuetong Zhao, Abbas Askar, Youjun Lu +7
Stellar-mass binary black holes (sBBHs) formed in globular clusters (GCs) are promising sources for multiband gravitational wave (GW) observations, particularly with low- and middl…
Probing the nature of dark matter via gravitational waves lensed by small dark matter halos
Xiao Guo, Youjun Lu
Dark matter (DM) occupies the majority of matter content in the universe and is probably cold (CDM). However, modifications to the standard CDM model may be required by the small-s…
On Variation of Light Curves and Broad Emission Lines for Periodic QSOs from co-rotating Supermassive binary black holes in elliptical orbits
Junqiang Ge, Youjun Lu, Changshuo Yan +1
Context. Periodic QSOs are considered as candidates of supermassive binary black hole (BBH) systems in galactic centers. Further confirmation of these candidates may require differ…
Phase-dependent study of near-infrared disk emission lines in LB-1
Jifeng Liu, Zheng Zheng, Roberto Soria +19
The mass, origin and evolutionary stage of the binary system LB-1 has been the subject of intense debate, following the claim that it hosts an 70 black hole, in st…
Two Different Accretion Classes in Seyfert 1 Galaxies and QSOs
Youjun Lu, Qingjuan Yu
The mass of the central black hole in Seyfert galaxies and QSOs can be determined from the broad emission lines and the reverberation method. Using the measured black hole mass and…
Stochastic Gravitational Wave Background and Eccentric Stellar Compact Binaries
Yuetong Zhao, Youjun Lu
Gravitational wave (GW) radiations from numerous cosmic stellar-compact-binaries form a stochastic GW background (GWB), which is expected to be detected by ground and space GW dete…
Spin evolution and mass distribution of the Galactic Binary Neutron Stars
Qingbo Chu, Youjun Lu, Shenghua Yu
Binary neutron stars (BNSs) detected in the Milky Way have the total masses distributing narrowly around , while the BNS merger GW190425 detected via gravitatio…
On Constraining the Growth History of Massive Black Holes via Their Distribution on the Spin-Mass Plane
Xiaoxia Zhang, Youjun Lu
The spin distribution of massive black holes (MBHs) contains rich information on the MBH growth history. In this paper, we investigate the spin evolution of MBHs by assuming that e…
The black hole mass versus velocity dispersion relation in QSOs/Active Galactic Nuclei: observational appearance and black hole growth
Qingjuan Yu, Youjun Lu
Studies of massive black holes (BHs) in nearby galactic centers have revealed a tight correlation between BH mass and galactic velocity dispersion. In this paper we investigate how…
Cyclic universe due to phantom and quintessence
Changjun Gao, Youjun Lu, You-Gen Shen
We explore a cyclic universe due to phantom and quintessence fields. We find that, in every cycle of the evolution of the universe, the phantom dominates the cosmic early history a…
The relativistic Iron K-alpha line from an accretion disc onto a static non-baryonic compact object
Youjun Lu, Diego F. Torres
This paper continues the study of the properties of an accretion disc rotating around a non-baryonic (assumed super-massive) compact object. This kind of objects, generically known…
On the Existence of Pulsars in the Vicinity of the Massive Black Hole in the Galactic Center
Fupeng Zhang, Youjun Lu, Qingjuan Yu
Pulsars, if existing and detectable in the immediate vicinity of the massive black hole (MBH) in the Galactic center (GC), may be used as a superb tool to probe both the environmen…
Extracting the Possible Intrinsic Relation between Radiative Efficiency and Mass of QSOs: a Maximum Likelihood Method and its Application to the SDSS DR7 QSOs
Fupeng Zhang, Youjun Lu
Radiative efficiencies of QSOs and its distribution encode rich information on the evolution of both masses and spins of massive black holes (MBHs) across cosmic time. In this pape…
Detectability of Nearby Binary Neutron Stars with Future sub-mHz Gravitational Wave Missions
Zhiwei Chen, Youjun Lu, Yuchao Luo +4
Binary neutron stars (BNSs) are one of the most important gravitational wave (GW) sources, which provide key insights to evolution of massive binary stars and nuclear physics. Beyo…
Constraints on QSO models from a relation between the QSO luminosity function and the local black hole mass function
Qingjuan Yu, Youjun Lu
QSOs are believed to be powered by accretion onto massive black holes (BHs). In this paper, assuming that each central BH in nearby galaxies has experienced the QSO phase and ignor…
A wide star-black-hole binary system from radial-velocity measurements
Jifeng Liu, Haotong Zhang, Andrew W. Howard +52
All stellar mass black holes have hitherto been identified by X-rays emitted by gas that is accreting onto the black hole from a companion star. These systems are all binaries with…
The Gravitational-Wave Physics II: Progress
Ligong Bian, Rong-Gen Cai, Shuo Cao +15
It has been a half-decade since the first direct detection of gravitational waves, which signifies the coming of the era of the gravitational-wave astronomy and gravitational-wave…
Dependence of the broad Fe K line on the physical parameters of AGN
Zhu Liu, Weimin Yuan, Youjun Lu +3
In this paper, the dependence of the broad Fe K line on the physical parameters of AGN, such as the black hole mass , accretion rate (equivalently represented by Edding…
Prospects for constraining the spin of the massive black hole at the Galactic center via the relativistic motion of a surrounding star
Qingjuan Yu, Fupeng Zhang, Youjun Lu
In this paper, we investigate the quality of constraining the spin of the massive black hole (MBH) at the Galactic center (GC) by using full general relativistic simulations of the…
On Testing the Kerr Metric of the Massive Black Hole in the Galactic Center via Stellar Orbital Motion: Full General Relativistic Treatment
Fupeng Zhang, Youjun Lu, Qingjuan Yu
The S-stars in the Galactic center (GC) are anticipated to provide unique dynamical constraint on the spin of the GC massive black hole (MBH). In this paper, we develop a fast full…
Testing Ghasemi-Nodehi-Bambi metric parameters with quasi-periodic oscillations
M. Ghasemi-Nodehi, Youjun Lu, Ju Chen +1
QPOs are seen as peak features in the X-ray power spectral density of stellar mass black holes and neutron stars, of which frequencies can be measured with high precision. These QP…
Quiescent luminous red galaxies (LRGs) as cosmic chronometers: on the significance of mass and environmental dependence
Gaochao Liu, Youjun Lu, Lizhi Xie +2
Massive luminous red galaxies (LRGs) are believed to be evolving passively and can be used as cosmic chronometers to estimate the Hubble constant. However, different LRGs may be lo…
SDSS-IV MaNGA: Stellar M/L gradients and the M/L-colour relation in galaxies
Junqiang Ge, Shude Mao, Youjun Lu +3
The stellar mass-to-light ratio gradient in SDSS band of a galaxy depends on its mass assembly history, which is imprinted in its morphology and gradients of…
Probing black hole accretion tracks, scaling relations and radiative efficiencies from stacked X-ray active galactic nuclei
Francesco Shankar, David H. Weinberg, Christopher Marsden +25
The masses of supermassive black holes at the centres of local galaxies appear to be tightly correlated with the mass and velocity dispersions of their galactic hosts. However, the…
Gravitational Lensing of Gravitational Waves from Astrophysical Sources: Theory, Detection, and Applications
Zhiwei Chen, Youjun Lu
Gravitational waves (GWs) from distant sources such as inspiralling and merging stellar-mass compact binaries, intermediate-mass and supermassive-binary-black-hole can be gravitati…
On the Full Spectrum Fitting of Luminous Red Galaxies by Using ULySS and STARLIGHT
Gaochao Liu, Youjun Lu, Xuelei Chen +2
In this paper, we select a sample of quiescent luminous red galaxies (LRGs) from Sloan Digital Sky Survey Data Release 7 (SDSS DR7) with signal-to-noise ratio (S/N) substantially h…
On using inspiralling supermassive binary black holes in the PTA frequency band as standard sirens to constrain dark energy
Changshuo Yan, Wen Zhao, Youjun Lu
Supermassive binary black holes (SMBBHs) in galactic centers may radiate gravitational wave (GW) in the nano-Hertz frequency band, which are expected to be detected by pulsar timin…
"Frog-eyes" in Astronomy: Monitoring Binary Radial Velocity Variations Through A Pair of Narrow-Band Filters
Chuanjie Zheng, Yang Huang, Jifeng Liu +13
Spectroscopic observations are a crucial step in driving major discoveries in the era of time-domain surveys. However, the pace of current spectroscopic surveys is increasingly una…
Hunting for the host galaxy groups of binary black holes and the application in constraining Hubble constant
Jiming Yu, Yu Wang, Wen Zhao +1
The discovery of gravitational-wave (GW) signals, produced by the coalescence of stellar-mass binary black holes (SBBHs), opens a new window to study the astrophysical origins and…