The analysis of light variation of M87 can help us understand the disk evolution.In the past decade,M87 has experienced several short-term light variabilities related to flares.We also find that there are year-scale X...The analysis of light variation of M87 can help us understand the disk evolution.In the past decade,M87 has experienced several short-term light variabilities related to flares.We also find that there are year-scale X-ray variations in the core of M87.Their light variability properties are similar to clumpy-ADAF.By re-analyzing 56Chandra observations from 2007 to 2019,we distinguish the“non-flaring state”from“flaring state”in the light variability.After removing flaring state data,we identify four gas clumps in the nucleus and all of them can be well fitted by the clumpy-ADAF model.The average mass accretion rate is~0.16M⊙yr^(-1).We analyze the photon index(Γ)-flux(2-10 keV)correlation between the non-flaring state and flaring state.For the non-flaring states,the flux is inversely proportional to the photon index.For the flaring states,we find no obvious correlation between the two parameters.In addition,we find that the flare always occurs at a high mass accretion rate,and after the luminosity of the flare reaches the peak,it will be accompanied by a sudden decrease in luminosity.Our results can be explained as that the energy released by magnetic reconnection destroys the structure of the accretion disk,thus the luminosity decreases rapidly and returns to normal levels thereafter.展开更多
We report the discovery of year-scale X-ray variation in the nuclear region of the M87 by reanalyze the eight Chandra observations from 2007 to 2008. The X-ray spectra are fitted and decomposed into disk and flaring c...We report the discovery of year-scale X-ray variation in the nuclear region of the M87 by reanalyze the eight Chandra observations from 2007 to 2008. The X-ray spectra are fitted and decomposed into disk and flaring components. This year-scale X-ray variability can be explained quite well by a simple clumpy accretion model. We conclude that the central super-massive black hole of M87 was accreting a cloud of ~ 0.5 M⊙at that time.展开更多
We study the lensing phenomena of the strong gravity regime of five-dimensional charged,equally rotating black holes with a cosmological constant,familiarly known as the Cvetic–Lu–Pope(CLP)black holes.These black ho...We study the lensing phenomena of the strong gravity regime of five-dimensional charged,equally rotating black holes with a cosmological constant,familiarly known as the Cvetic–Lu–Pope(CLP)black holes.These black holes are characterized by three observable parameters,the mass M,the charge Q and the angular momentum J,in addition to the cosmological constant.We investigate the strong gravitational lensing observables,mainly the photon sphere radius,the minimum impact parameter,the deflection angle,the angular size,and the magnification of the relativistic images.We model the M87 and SgrA*for these observables.We also focus on the relativistic time delay effect in the strong-field regime of gravity and the impact of the observable on it.The analytical expressions for the observables of the relativistic images with vanishing angular momentum(j=0)are discussed in some detail.We shed a light on the gravitational time delay effect by incorporating the lensing observables.The gravitational time delay has a direct consequence on the photon sphere radius and hence on the quasinormal modes.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11863006,U1838203,and U2038104)the Science&Technology Department of Yunnan Province—Yunnan University Joint Funding(2019FY003005)the Bureau of International Cooperation,Chinese Academy of Sciences under the grant GJHZ1864。
文摘The analysis of light variation of M87 can help us understand the disk evolution.In the past decade,M87 has experienced several short-term light variabilities related to flares.We also find that there are year-scale X-ray variations in the core of M87.Their light variability properties are similar to clumpy-ADAF.By re-analyzing 56Chandra observations from 2007 to 2019,we distinguish the“non-flaring state”from“flaring state”in the light variability.After removing flaring state data,we identify four gas clumps in the nucleus and all of them can be well fitted by the clumpy-ADAF model.The average mass accretion rate is~0.16M⊙yr^(-1).We analyze the photon index(Γ)-flux(2-10 keV)correlation between the non-flaring state and flaring state.For the non-flaring states,the flux is inversely proportional to the photon index.For the flaring states,we find no obvious correlation between the two parameters.In addition,we find that the flare always occurs at a high mass accretion rate,and after the luminosity of the flare reaches the peak,it will be accompanied by a sudden decrease in luminosity.Our results can be explained as that the energy released by magnetic reconnection destroys the structure of the accretion disk,thus the luminosity decreases rapidly and returns to normal levels thereafter.
基金supported by the CASSACA Postdoc Grant(from the Chinese Academy of Sciences,CAS)the Visiting Scholarship Grant(administered by the CAS South America Center for Astronomy,CASSACA,NAOC)+3 种基金Science&Technology Department of Yunnan Province–Yunnan University Joint Funding(2019FY003005)the National Natural Science Foundation of China(Grant Nos.11203019 and 11863006)supported by the Young Researcher Grant of National Astronomical Observatories,Chinese Academy of Science and the National Natural Science Foundation of China(Grant No.11803044)sponsored(in part)by the Chinese Academy of Sciences(CAS),through a grant to the CAS South America Center for Astronomy(CASSACA)。
文摘We report the discovery of year-scale X-ray variation in the nuclear region of the M87 by reanalyze the eight Chandra observations from 2007 to 2008. The X-ray spectra are fitted and decomposed into disk and flaring components. This year-scale X-ray variability can be explained quite well by a simple clumpy accretion model. We conclude that the central super-massive black hole of M87 was accreting a cloud of ~ 0.5 M⊙at that time.
基金supported by the National Natural Science Foundation of China under Grants Nos.12475056,12347177,and 12247101,the 111 Project under Grant No.B20063Lanzhou City's scientific research funding subsidy to Lanzhou Universitythe Gansu Province Major Scientific and Technological Special Project。
文摘We study the lensing phenomena of the strong gravity regime of five-dimensional charged,equally rotating black holes with a cosmological constant,familiarly known as the Cvetic–Lu–Pope(CLP)black holes.These black holes are characterized by three observable parameters,the mass M,the charge Q and the angular momentum J,in addition to the cosmological constant.We investigate the strong gravitational lensing observables,mainly the photon sphere radius,the minimum impact parameter,the deflection angle,the angular size,and the magnification of the relativistic images.We model the M87 and SgrA*for these observables.We also focus on the relativistic time delay effect in the strong-field regime of gravity and the impact of the observable on it.The analytical expressions for the observables of the relativistic images with vanishing angular momentum(j=0)are discussed in some detail.We shed a light on the gravitational time delay effect by incorporating the lensing observables.The gravitational time delay has a direct consequence on the photon sphere radius and hence on the quasinormal modes.
