The gold mineralization in the Longtoushan hydrothermal gold deposit is concentrated within the contact zone of the granitic complex. Whole rock geochemistry and in-situ U-Pb and Hf isotopic data were used to constrai...The gold mineralization in the Longtoushan hydrothermal gold deposit is concentrated within the contact zone of the granitic complex. Whole rock geochemistry and in-situ U-Pb and Hf isotopic data were used to constrain the genesis and age of the granites and related Cu-Au mineralization in the Longtoushan Deposit. The granites mainly consist of the granite porphyry, rhyolite porphyry, porphyritic granite and quartz porphyry. LA-ICP-MS U-Pb dating of zircons from the granite porphyry, rhyolite porphyry and quartz porphyry indicates that they intruded from ca. 94 to 97 Ma. These intrusions exhibit similar trace element characteristics, i.e., right-dipping REE patterns, depletion of Ba, Sr, P and Ti, and enrichment of Th, U, Nd, Zr and Hf. The εHf(t) values of zircons from the granite porphyry, rhyolite porphyry and quartz porphyry range from-26.81 to-8.19,-8.12 to-5.33, and-8.99 to-5.83, respectively, suggesting that they were mainly derived from the partial melting of the Proterozoic crust. The Cu-Au mineralization is mainly related to the rhyolite porphyry and porphyritic granite, respectively. The Longtoushan granites were most likely formed in a post-collisional extensional environment, and the deposit is a part of the Late Yanshanian magmatism related mineralization in the Dayaoshan area and its adjacent areas.展开更多
We use a sample of 111 radio galaxies with redshift z 〈 0.3 to investigate their nuclear properties. The black hole masses of the sources in this sample are estimated with the velocity dispersion/luminosity of the ga...We use a sample of 111 radio galaxies with redshift z 〈 0.3 to investigate their nuclear properties. The black hole masses of the sources in this sample are estimated with the velocity dispersion/luminosity of the galaxies, or the width of the broad-lines. We find that the excitation index, the relative intensity of low and high excitation lines, is correlated with the Eddington ratio for this sample. The size of the narrow-line region （NLR） was found to vary with ionizing luminosity as RNLR ∝ Lion^0.25 （Liu et al. 2013）. Using this empirical relation, we find that the correlation between the excitation index and the Eddington ratio can be reproduced by photoionization models. We adopt two sets of spectral energy distributions （SEDs）, with or without a big blue bump in ultraviolet as the ionizing continuum, and infer that the modeled correlation between the excitation index and the Eddington ratio is insensitive to the applied SED. This means that the difference between high excitation galaxies and low excitation galaxies is not caused by the different accretion modes in these sources. Instead, it may be caused by the size of the NLR.展开更多
The peaks in the spectra of the accretion disks surrounding massive black holes in quasars are in the far-UV or soft X-ray band, which are usually not observed. However, in the disk corona model, soft photons from the...The peaks in the spectra of the accretion disks surrounding massive black holes in quasars are in the far-UV or soft X-ray band, which are usually not observed. However, in the disk corona model, soft photons from the disk are Comptonized to high energy in the hot corona, and the hard X-ray spectra （lu- minosity and spectral shape） contain information on the incident spectra from the disk. The values of black hole spin parameter a. are inferred from the spectral fitting, which are spread over a large range, ~ -0.94 to 0.998. We find that the inclination angles and mass accretion rates are well determined by the spectral fitting, but the results are sensitive to the accuracy of black hole mass estimates. No tight constraints on the black hole spins are achieved, if the uncertainties in black hole mass measurements are a factor of four, which are typical for the single-epoch reverberation mapping method. Recently, the accuracy of black hole mass measurement has been significantly improved to 0.2 - 0.4 dex with the velocity resolved reverber- ation mapping method. The black hole spin can be well constrained if the mass measurement accuracy is 50%. In the accretion disk corona scenario, a fraction of power dissipated in the disk is transported into the corona, and therefore the accretion disk is thinner than a bare disk for the same mass accretion rate, because the radiation pressure in the disk is reduced. We find that the thin disk approximation, H/R ≤0. 1, is still valid if 0.3 〈 m 〈 0.5, provided half of the dissipated power is radiated in the corona above the disk.展开更多
We present the novel capabilities of the enhanced X-ray Timing and Polarimetry(eXTP)mission to study the strong gravity region around stellar-mass black holes in X-ray binary systems and supermassive black holes in ac...We present the novel capabilities of the enhanced X-ray Timing and Polarimetry(eXTP)mission to study the strong gravity region around stellar-mass black holes in X-ray binary systems and supermassive black holes in active galactic nuclei.eXTP can combine X-ray spectral,timing,and polarimetric techniques to study the accretion process near black holes,measure black hole masses and spins,and test Einstein's theory of General Relativity in the strong field regime.We show how eXTP can improve the current measurements of black holes of existing X-ray missions and we discuss the scientific questions that can be addressed.展开更多
The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray varia...The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray variability of known sources in 0.5-4 keV,at a combination of detecting sensitivity and cadence that is not accessible to the previous and current wide-field monitoring missions.EP can perform quick characterisation of transients or outbursts with a Wolter-I X-ray telescope onboard.In this paper,the science objectives of the EP mission are presented.EP is expected to enlarge the sample of previously known or predicted but rare types of transients with a wide range of timescales.Among them,fast extragalactic transients will be surveyed systematically in soft X-rays,which includeγ-ray bursts and their variants,supernova shock breakouts,and the predicted X-ray transients associated with binary neutron star mergers.EP will detect X-ray tidal disruption events and outbursts from active galactic nuclei,possibly at an early phase of the flares for some.EP will monitor the variability and outbursts of X-rays from white dwarfs,neutron stars and black holes in our and neighbouring galaxies at flux levels fainter than those detectable by the current instruments,and is expected to discover new objects.A large sample of stellar X-ray flares will also be detected and characterised.In the era of multi-messenger astronomy,EP has the potential of detecting the possible X-ray counterparts of gravitational wave events,neutrino sources,and ultra-high energyγ-ray and cosmic ray sources.EP is expected to help advance the studies of extreme objects and phenomena revealed in the dynamic X-ray universe,and their underlying physical processes.Besides EP's strength in time-domain science,its follow-up telescope,with excellent performance,will also enable advances in many areas of X-ray astronomy.展开更多
基金supported by the Project of Innovationdriven Plan in Central South University (No. 2015CX008)the Fundamental Reserch Funds for the Central Universities of Central South University (No. 2015zzts071)
文摘The gold mineralization in the Longtoushan hydrothermal gold deposit is concentrated within the contact zone of the granitic complex. Whole rock geochemistry and in-situ U-Pb and Hf isotopic data were used to constrain the genesis and age of the granites and related Cu-Au mineralization in the Longtoushan Deposit. The granites mainly consist of the granite porphyry, rhyolite porphyry, porphyritic granite and quartz porphyry. LA-ICP-MS U-Pb dating of zircons from the granite porphyry, rhyolite porphyry and quartz porphyry indicates that they intruded from ca. 94 to 97 Ma. These intrusions exhibit similar trace element characteristics, i.e., right-dipping REE patterns, depletion of Ba, Sr, P and Ti, and enrichment of Th, U, Nd, Zr and Hf. The εHf(t) values of zircons from the granite porphyry, rhyolite porphyry and quartz porphyry range from-26.81 to-8.19,-8.12 to-5.33, and-8.99 to-5.83, respectively, suggesting that they were mainly derived from the partial melting of the Proterozoic crust. The Cu-Au mineralization is mainly related to the rhyolite porphyry and porphyritic granite, respectively. The Longtoushan granites were most likely formed in a post-collisional extensional environment, and the deposit is a part of the Late Yanshanian magmatism related mineralization in the Dayaoshan area and its adjacent areas.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11173043 and 11233006)the Strategic Priority Research Program “the Emergence of Cosmological Structures” of the CAS (Grant No. XDB09000000)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘We use a sample of 111 radio galaxies with redshift z 〈 0.3 to investigate their nuclear properties. The black hole masses of the sources in this sample are estimated with the velocity dispersion/luminosity of the galaxies, or the width of the broad-lines. We find that the excitation index, the relative intensity of low and high excitation lines, is correlated with the Eddington ratio for this sample. The size of the narrow-line region （NLR） was found to vary with ionizing luminosity as RNLR ∝ Lion^0.25 （Liu et al. 2013）. Using this empirical relation, we find that the correlation between the excitation index and the Eddington ratio can be reproduced by photoionization models. We adopt two sets of spectral energy distributions （SEDs）, with or without a big blue bump in ultraviolet as the ionizing continuum, and infer that the modeled correlation between the excitation index and the Eddington ratio is insensitive to the applied SED. This means that the difference between high excitation galaxies and low excitation galaxies is not caused by the different accretion modes in these sources. Instead, it may be caused by the size of the NLR.
基金supported by the National Natural Science Foundation of China(Grant Nos.11173043,11121062,11233006,11073020,11373056 and 11473054)the Fundamental Research Funds for the Central Universities(WK2030220004)+1 种基金the CAS/SAFEA International Partnership Program for Creative Research Teams(KJCX2-YW-T23)Shanghai Municipality
文摘The peaks in the spectra of the accretion disks surrounding massive black holes in quasars are in the far-UV or soft X-ray band, which are usually not observed. However, in the disk corona model, soft photons from the disk are Comptonized to high energy in the hot corona, and the hard X-ray spectra （lu- minosity and spectral shape） contain information on the incident spectra from the disk. The values of black hole spin parameter a. are inferred from the spectral fitting, which are spread over a large range, ~ -0.94 to 0.998. We find that the inclination angles and mass accretion rates are well determined by the spectral fitting, but the results are sensitive to the accuracy of black hole mass estimates. No tight constraints on the black hole spins are achieved, if the uncertainties in black hole mass measurements are a factor of four, which are typical for the single-epoch reverberation mapping method. Recently, the accuracy of black hole mass measurement has been significantly improved to 0.2 - 0.4 dex with the velocity resolved reverber- ation mapping method. The black hole spin can be well constrained if the mass measurement accuracy is 50%. In the accretion disk corona scenario, a fraction of power dissipated in the disk is transported into the corona, and therefore the accretion disk is thinner than a bare disk for the same mass accretion rate, because the radiation pressure in the disk is reduced. We find that the thin disk approximation, H/R ≤0. 1, is still valid if 0.3 〈 m 〈 0.5, provided half of the dissipated power is radiated in the corona above the disk.
基金supported by China’s Space Origins Exploration Programsupported by the National Natural Science Foundation of China(Grant No.12333007)+3 种基金the International Partnership Program of Chinese Academy of Sciences(Grant No.113111KYSB20190020)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)support from the Academy of Finland(Grant No.355672)supported in part by Nord Forsk.
文摘We present the novel capabilities of the enhanced X-ray Timing and Polarimetry(eXTP)mission to study the strong gravity region around stellar-mass black holes in X-ray binary systems and supermassive black holes in active galactic nuclei.eXTP can combine X-ray spectral,timing,and polarimetric techniques to study the accretion process near black holes,measure black hole masses and spins,and test Einstein's theory of General Relativity in the strong field regime.We show how eXTP can improve the current measurements of black holes of existing X-ray missions and we discuss the scientific questions that can be addressed.
基金supported by Strategic Priority Program on Space Science of Chinese Academy of Sciences,in collaboration with ESA,MPE and CNES(Grant Nos.XDA15310000,and XDA15052100)supported by the National Natural Science Foundation of China(Grant Nos.61234003,61434004,and 61504141)CAS Interdisciplinary Project(Grant No.KJZD-EW-L11-04)。
文摘The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray variability of known sources in 0.5-4 keV,at a combination of detecting sensitivity and cadence that is not accessible to the previous and current wide-field monitoring missions.EP can perform quick characterisation of transients or outbursts with a Wolter-I X-ray telescope onboard.In this paper,the science objectives of the EP mission are presented.EP is expected to enlarge the sample of previously known or predicted but rare types of transients with a wide range of timescales.Among them,fast extragalactic transients will be surveyed systematically in soft X-rays,which includeγ-ray bursts and their variants,supernova shock breakouts,and the predicted X-ray transients associated with binary neutron star mergers.EP will detect X-ray tidal disruption events and outbursts from active galactic nuclei,possibly at an early phase of the flares for some.EP will monitor the variability and outbursts of X-rays from white dwarfs,neutron stars and black holes in our and neighbouring galaxies at flux levels fainter than those detectable by the current instruments,and is expected to discover new objects.A large sample of stellar X-ray flares will also be detected and characterised.In the era of multi-messenger astronomy,EP has the potential of detecting the possible X-ray counterparts of gravitational wave events,neutrino sources,and ultra-high energyγ-ray and cosmic ray sources.EP is expected to help advance the studies of extreme objects and phenomena revealed in the dynamic X-ray universe,and their underlying physical processes.Besides EP's strength in time-domain science,its follow-up telescope,with excellent performance,will also enable advances in many areas of X-ray astronomy.
