The observations of varying broad iron lines during the state transition of the black hole X-ray binaries have been accumulating.In this work,the relation between the normalized intensity and the width of iron lines i...The observations of varying broad iron lines during the state transition of the black hole X-ray binaries have been accumulating.In this work,the relation between the normalized intensity and the width of iron lines is investigated,in order to understand better the variation of iron lines and possibly its connection to state transition.Considering the uncertainties due to ionization and illuminating X-rays,only the effects of geometry and gravity are taken into account.Three scenarios were studied,i.e.,the continuous disk model,the innermost annulus model,and the cloud model.As shown by our calculations,at given iron width,the line flux of the cloud model is smaller than that of the continuous disk model;while for the innermost annulus model,the width is almost unrelated with the flux.The range of the line strength depends on both the BH spin and the inclination of the disk.We then apply to the observation of MAXI J1631-479 by Nuclear Spectroscopic Telescope Array during its decay from the soft state to the intermediate state.We estimated the relative line strength and width according to the spectral fitting results in Xu et al.,and then compared with our theoretical width-flux relation.It was found that the cloud model was more favored.We further modeled the iron line profiles,and found that the cloud model can explain both the line profile and its variation with reasonable parameters.展开更多
Recent studies reveal that weak Lyα emission line may be a ubiquitous feature of nearby BL Laceratae objects(BL Lacs). We present a survey of the Lyα emission lines in BL Lacs, with a focus on data obtained by the C...Recent studies reveal that weak Lyα emission line may be a ubiquitous feature of nearby BL Laceratae objects(BL Lacs). We present a survey of the Lyα emission lines in BL Lacs, with a focus on data obtained by the Cosmic Origins Spectrograph onboard the Hubble Space Telescope. Among the11 selected targets, seven show a clear detection of the intrinsic Lyα emission line, while one manifests a marginal detection. Two of these intrinsic Lyα lines are newly detected in this work(FBQS J1217+3007 and3 C 66 A). Most selected BL Lacs are either high or intermediate-frequency peaked BL Lacs, with the only exception being one low-frequency peaked BL Lac. A strong anti-correlation between the line equivalent width and the continuum luminosity was found. The possible sources of ionizing photons that are responsible for production of the Lyα emission line are studied based on a widely accepted detailed accretion-jet model. It is found that the clouds of the broad line region are unlikely to be located in the jet cone region with an inclination angle of less than 10 degrees. Contributions from the jet and disk to the emission lines are found to be comparable. Additionally, a possible way to constrain the accretion rate from the emission line is proposed.展开更多
A model of an inhomogeneous accretion flow,in which cold clumps are surrounded by hot gas or corona,has been proposed to explain the spectral features of black hole X-ray binaries.In this work,we try to find possible ...A model of an inhomogeneous accretion flow,in which cold clumps are surrounded by hot gas or corona,has been proposed to explain the spectral features of black hole X-ray binaries.In this work,we try to find possible observational features in the continuum that can indicate the existence of clumps.The spectra of an inhomogeneous accretion flow are calculated via the Monte Carlo method.Since the corresponding accretion flow is unsteady and complex,the accretion flow is described by a set of free parameters,the ranges of which can include the real cases.The influences of the parameters are investigated.It is found that the thermal component of the spectra deviates from multi-color black body spectra in the middle power-law part.On one hand,a warp appears due to the gaps between the clumps and the outer cold disk,and on the other hand,the slope of the line connecting the thermal peaks deviates from 4/3.The warp feature,as well as the correlation between the thermal peak at higher frequency and the spectral index,possibly indicate the existence of clumps,and are worthy of further investigation with more self-consistent models.展开更多
Jet launching in radio loud(RL) quasars is one of the fundamental problems in astrophysics. Exploring the differences in the inner accretion disk properties between RL and radio quiet(RQ) quasars might yield helpful c...Jet launching in radio loud(RL) quasars is one of the fundamental problems in astrophysics. Exploring the differences in the inner accretion disk properties between RL and radio quiet(RQ) quasars might yield helpful clues to this puzzle. We previously discovered that the shorter term UV/optical variations of quasars are bluer than the longer term ones, i.e., the so-called timescaledependent color variation. This is consistent with the scheme that the faster variations come from the inner and hotter disk regions,thus providing a useful tool to map the accretion disk which is otherwise unresolvable. In this work we compare the UV/optical variations of RL quasars in SDSS Stripe 82 to those of several RQ samples, including those matched in redshift-luminosity-black hole mass and/or color-magnitude. We find that while both RL and RQ populations appear bluer when they brighten, RL quasars potentially show a weaker/flatter dependence on timescale in their color variation. We further find that while both RL and RQ populations on average show similar variation amplitudes at long timescales, fast variations of RL sources appear weaker/smaller(at timescales of ~25-300 d in the observer's frame), and the difference is more prominent in the g-band than in the r-band.Inhomogeneous disk simulations can qualitatively reproduce these observed differences if the inner accretion disk of RL quasars fluctuates less based on simple toy models. Though the implications are likely model dependent, the discovery points to an interesting diagram that magnetic fields in RL quasars may be prospectively stronger and play a key role in both jet launching and the stabilization of the inner accretion disk.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant Nos.U2038108,12192220,12192223 and 12133008the National SKA Program of China(No.2020SKA0110102)supported in part by the Youth Innovation Promotion Association of CAS(Y202064)。
文摘The observations of varying broad iron lines during the state transition of the black hole X-ray binaries have been accumulating.In this work,the relation between the normalized intensity and the width of iron lines is investigated,in order to understand better the variation of iron lines and possibly its connection to state transition.Considering the uncertainties due to ionization and illuminating X-rays,only the effects of geometry and gravity are taken into account.Three scenarios were studied,i.e.,the continuous disk model,the innermost annulus model,and the cloud model.As shown by our calculations,at given iron width,the line flux of the cloud model is smaller than that of the continuous disk model;while for the innermost annulus model,the width is almost unrelated with the flux.The range of the line strength depends on both the BH spin and the inclination of the disk.We then apply to the observation of MAXI J1631-479 by Nuclear Spectroscopic Telescope Array during its decay from the soft state to the intermediate state.We estimated the relative line strength and width according to the spectral fitting results in Xu et al.,and then compared with our theoretical width-flux relation.It was found that the cloud model was more favored.We further modeled the iron line profiles,and found that the cloud model can explain both the line profile and its variation with reasonable parameters.
基金supported by the National Key R&D Program of China (2017YFA0402600)the National Natural Science Foundation of China (Grant Nos. 11525312 and U1531130)
文摘Recent studies reveal that weak Lyα emission line may be a ubiquitous feature of nearby BL Laceratae objects(BL Lacs). We present a survey of the Lyα emission lines in BL Lacs, with a focus on data obtained by the Cosmic Origins Spectrograph onboard the Hubble Space Telescope. Among the11 selected targets, seven show a clear detection of the intrinsic Lyα emission line, while one manifests a marginal detection. Two of these intrinsic Lyα lines are newly detected in this work(FBQS J1217+3007 and3 C 66 A). Most selected BL Lacs are either high or intermediate-frequency peaked BL Lacs, with the only exception being one low-frequency peaked BL Lac. A strong anti-correlation between the line equivalent width and the continuum luminosity was found. The possible sources of ionizing photons that are responsible for production of the Lyα emission line are studied based on a widely accepted detailed accretion-jet model. It is found that the clouds of the broad line region are unlikely to be located in the jet cone region with an inclination angle of less than 10 degrees. Contributions from the jet and disk to the emission lines are found to be comparable. Additionally, a possible way to constrain the accretion rate from the emission line is proposed.
基金supported by the National Natural Science Foundation of China under grants 11333004, 11133005, 11573051 and U1531130the Fundamental Research Funds for the Central Universities under grant 20720150032+5 种基金supported in part by the Youth Innovation Promotion Association of CAS (id. 2016243)the National Basic Research Program of China (973 Program, grant 2014CB845800)the Strategic Priority Research Program ‘The Emergence of Cosmological Structures’ of CAS (grant XDB09000000)the CAS/SAFEA International Partnership Program for Creative Research Teamsthe Natural Science Foundation of Shanghai (grant 17ZR1435800)sponsored in part by Shanghai Sailing Program (No. 17YF1422600)
文摘A model of an inhomogeneous accretion flow,in which cold clumps are surrounded by hot gas or corona,has been proposed to explain the spectral features of black hole X-ray binaries.In this work,we try to find possible observational features in the continuum that can indicate the existence of clumps.The spectra of an inhomogeneous accretion flow are calculated via the Monte Carlo method.Since the corresponding accretion flow is unsteady and complex,the accretion flow is described by a set of free parameters,the ranges of which can include the real cases.The influences of the parameters are investigated.It is found that the thermal component of the spectra deviates from multi-color black body spectra in the middle power-law part.On one hand,a warp appears due to the gaps between the clumps and the outer cold disk,and on the other hand,the slope of the line connecting the thermal peaks deviates from 4/3.The warp feature,as well as the correlation between the thermal peak at higher frequency and the spectral index,possibly indicate the existence of clumps,and are worthy of further investigation with more self-consistent models.
基金supported by the National Basic Research Program of China(Grant No.2015CB857005)the National Natural Science Foundation of China(Grant Nos.11233002,11421303,11503024,and 11873045)+3 种基金support from Chinese Top-notch Young Talents ProgramFrontier Science Key Research Program,China Academy Sciences(Grant No.QYZDJ-SSW-SLH006)support from the Fundamental Research Funds for the Central Universitiesthe grant from the Ministry of Science and Technology of China(Grant No.2016YFA0400704)
文摘Jet launching in radio loud(RL) quasars is one of the fundamental problems in astrophysics. Exploring the differences in the inner accretion disk properties between RL and radio quiet(RQ) quasars might yield helpful clues to this puzzle. We previously discovered that the shorter term UV/optical variations of quasars are bluer than the longer term ones, i.e., the so-called timescaledependent color variation. This is consistent with the scheme that the faster variations come from the inner and hotter disk regions,thus providing a useful tool to map the accretion disk which is otherwise unresolvable. In this work we compare the UV/optical variations of RL quasars in SDSS Stripe 82 to those of several RQ samples, including those matched in redshift-luminosity-black hole mass and/or color-magnitude. We find that while both RL and RQ populations appear bluer when they brighten, RL quasars potentially show a weaker/flatter dependence on timescale in their color variation. We further find that while both RL and RQ populations on average show similar variation amplitudes at long timescales, fast variations of RL sources appear weaker/smaller(at timescales of ~25-300 d in the observer's frame), and the difference is more prominent in the g-band than in the r-band.Inhomogeneous disk simulations can qualitatively reproduce these observed differences if the inner accretion disk of RL quasars fluctuates less based on simple toy models. Though the implications are likely model dependent, the discovery points to an interesting diagram that magnetic fields in RL quasars may be prospectively stronger and play a key role in both jet launching and the stabilization of the inner accretion disk.