Motivated by recent studies of the perturbation of the Magellanic Clouds(MCs)on the Milky Way(MW)and the planned multi-band wide-field deep survey named Chinese Space Station Telescope(CSST),we explore the detection l...Motivated by recent studies of the perturbation of the Magellanic Clouds(MCs)on the Milky Way(MW)and the planned multi-band wide-field deep survey named Chinese Space Station Telescope(CSST),we explore the detection limit of the MW reflex motion due to the MCs infall in different observation precision using an MW-MCs-mass galaxy from MAGPIE simulation to provide a reference for the CSST survey.By involving different errors of distance,proper motion,and radial velocity,we investigate the reflex motion characterized by the velocity shift in each velocity component.We find the strongest shifts in the tangential velocities,which align with the motion direction of the MCs.In the ideal case that distance errors dominate,we find a relative distance error of 10%can allow the reliable detection of velocity shifts in tangential velocities within 100 kpc,and a relative distance error of 30%is the minimum requirement to detect the reliable tangential velocity shifts of about 40kms^(-1)within 50 kpc.Different errors of proper motions in combination with a relative distance error of 10%or 20%show an error of 0.1 mas yr^(-1)in proper motions can guarantee the reliable detection of velocity shifts in V_(l)and V_(b)up to 80-100 kpc and an error of 0.15 mas yr^(-1)is the minimum requirement.In the other ideal case that radial velocity errors dominate,we find a radial velocity error of 20kms^(-1)can present reliable reflex motion in line-of-sight velocity up to 70 kpc,while the detection volume will be reduced to 50 kpc as the radial velocity error increases to 40kms^(-1).When the radial velocity error is larger than 60kms^(-1),the velocity shifts cannot be detected anymore.In addition,we find that reliable detection of reflex motion requires at least 20%of the whole sample.展开更多
Seamount is a unique deep-sea ecosystem widely distributed in the world.Its biodiversity is vibrant due to its specific geographical and hydrological conditions.However,the diversity and features of foraminifera in su...Seamount is a unique deep-sea ecosystem widely distributed in the world.Its biodiversity is vibrant due to its specific geographical and hydrological conditions.However,the diversity and features of foraminifera in such an environment have rarely been studied.We extracted environmental DNA(eDNA)in sedime nts and amplified the partial small subunit ribo somal DNA(SSU rDNA)of fo raminife ra to understand the foraminiferal diversity from four sites in Magellan Seamount(Western Pacific Ocean).Partial S SU rDNA sequencing was conducted and 912979 foraminiferal reads were obtained and gathered into 266 operational taxonomic units(OTUs).In the available dataset,a high proportion of rare OTUs and low identity OTUs in each studied sample showed that the Magellan Seamount foraminiferal community might have a high genetic novelty.The relative abundance of foraminifera varied between replicates probably due to the existence of bias in amplification process and patchiness of the deep-sea floor.It showed that the Magellan Seamount has a relatively high benthic foraminiferal diversity characterized mainly by monothalamiids(76.37%of total reads)in association with rotaliids(19.03%of total reads),including planktic foraminiferal sequences(38.58%of rotaliids;7.36%of total reads).The remaining reads were assigned to miliolids(0.83%of total reads)and textulariids(0.66%of total reads),and 3.11%of total reads are unassigned to a specific family.The co mparative analysis with foraminiferal assemblage s from coastal and deep-sea environme nts indicated that seamounts could aggregate species from a nearby deep-sea.展开更多
The alkaline oceanic island basalts(OIBs)with under-saturated SiO2 and high contents of CaO and alkaline are usually attributed to mantle sources different from typical tholeiitic OIBs.Based on the results of high pre...The alkaline oceanic island basalts(OIBs)with under-saturated SiO2 and high contents of CaO and alkaline are usually attributed to mantle sources different from typical tholeiitic OIBs.Based on the results of high pressure and temperature experiment study,the genesis of silica under-saturated alkaline basaltic melts could be explained by the role of CO2,thus,the genetic relationship of alkaline basalts with CO2 has become a topic of relevance because it is closely related to the deep carbon cycle.The Magellan Seamount chain in the West Pacific Seamount Province has wide distribution of alkali basalts.For the first time,we collected alkaline basalt samples from the Kocebu Seamount of the Magellan Seamount chain and found that magmatic apatites widely occur in the less evolved volcanic rock samples,and the high contents of phosphorus should be a feature of the alkaline OIBs of the Magellan Seamounts.Compared with typical OIBs,these alkaline volcanic rocks have higher CaO and P2O5,lower SiO2 content,negative anomaly of high field strength elements(HFSEs),more distinctly negative anomaly of potassium(K)and the ubiquity of titanaugite,indicating a CO2-rich mantle source.Based on the relatively high K2O and TiO2 contents and La/Yb ratio and low MgO content of these alkaline rocks,we suggest that the volcanic rocks of the Magellan Seamounts are originated from carbonated eclogites derived possibly from ancient subducted altered oceanic crust.展开更多
A conservative constraint on the rest mass of the photon can be estimated under the assump- tion that the frequency dependence of dispersion from astronomical sources is mainly contributed by the nonzero photon mass e...A conservative constraint on the rest mass of the photon can be estimated under the assump- tion that the frequency dependence of dispersion from astronomical sources is mainly contributed by the nonzero photon mass effect. Photon mass limits have been set earlier through the optical emissions of the Crab Nebula pulsar, but we demonstrate that these limits can be significantly improved with the dispersion measure （DM） measurements of radio pulsars in the Large and Small Magellanic Clouds. The combination of DM measurements of pulsars and distances of the Magellanic Clouds provides a strict upper limit on the photon mass as low as mγ≤2.0 ～ 10-45 g, which is at least four orders of magnitude smaller than the constraint from the Crab Nebula pulsar. Although our limit is not as tight as the current best result （～ 10-47 g） from a fast radio burst （FRB 150418） at a cosmological distance, the cosmological origin of FRB 150418 remains under debate; and our limit can reach the same high precision of FRB 150418 when it has an extragalactic origin （ ～10-45 g）.展开更多
The 80 high-mass X-ray binary （HMXB） pulsars that are known to reside in the Magellanic Clouds （MCs） have been observed by the XMM-Newton and Chandra X-ray telescopes on a regular basis for 15 years, and the XMM-N...The 80 high-mass X-ray binary （HMXB） pulsars that are known to reside in the Magellanic Clouds （MCs） have been observed by the XMM-Newton and Chandra X-ray telescopes on a regular basis for 15 years, and the XMM-Newton and Chandra archives contain nearly complete information about the duty cycles of the sources with spin periods Ps 〈 100 s. We have reprocessed the archival data from both observatories and we combined the output products with all the published observations of 31 MC pulsars with Ps 〈 100 s in an attempt to investigate the faintest X-ray emission states of these objects that occur when accretion to the polar caps proceeds at the smallest possible rates. These states determine the so-called propeller lines of the accreting pulsars and yield information about the magnitudes of their surface magnetic fields. We have found that the faintest states of the pulsars segregate into five discrete groups which obey to a high degree of accuracy the theoretical relation between spin period and X-ray luminosity. So the entire population of these pulsars can be described by just five propeller lines and the five corresponding magnetic moments （0.29, 0.53, 1.2, 2.9 and 7.3, in units of 1030 G cma）.展开更多
基金supported by the National Key Research and Development Program of China No.2019YFA0405504the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-B03+4 种基金the National Natural Science Foundation of China(NSFC)grant Nos.11988101,11890694,12103062,12273027,12273053 and 12173046CAS Project for Young Scientists in Basic Research grant No.YSBR-062support from the K.C.Wong Foundationthe Sichuan Youth Science and Technology Innovation Research Team(grant No.21CXTD0038)the Innovation Team Funds of China West Normal University(grant No.KCXTD2022-6)。
文摘Motivated by recent studies of the perturbation of the Magellanic Clouds(MCs)on the Milky Way(MW)and the planned multi-band wide-field deep survey named Chinese Space Station Telescope(CSST),we explore the detection limit of the MW reflex motion due to the MCs infall in different observation precision using an MW-MCs-mass galaxy from MAGPIE simulation to provide a reference for the CSST survey.By involving different errors of distance,proper motion,and radial velocity,we investigate the reflex motion characterized by the velocity shift in each velocity component.We find the strongest shifts in the tangential velocities,which align with the motion direction of the MCs.In the ideal case that distance errors dominate,we find a relative distance error of 10%can allow the reliable detection of velocity shifts in tangential velocities within 100 kpc,and a relative distance error of 30%is the minimum requirement to detect the reliable tangential velocity shifts of about 40kms^(-1)within 50 kpc.Different errors of proper motions in combination with a relative distance error of 10%or 20%show an error of 0.1 mas yr^(-1)in proper motions can guarantee the reliable detection of velocity shifts in V_(l)and V_(b)up to 80-100 kpc and an error of 0.15 mas yr^(-1)is the minimum requirement.In the other ideal case that radial velocity errors dominate,we find a radial velocity error of 20kms^(-1)can present reliable reflex motion in line-of-sight velocity up to 70 kpc,while the detection volume will be reduced to 50 kpc as the radial velocity error increases to 40kms^(-1).When the radial velocity error is larger than 60kms^(-1),the velocity shifts cannot be detected anymore.In addition,we find that reliable detection of reflex motion requires at least 20%of the whole sample.
基金the Science&Technology Basic Resources Investigation Program of China(No.2017FY100804)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB42000000)+5 种基金the National Program on Global Change and Air-Sea Interaction(No.GASIGEOGE-04)the Key Program of National Natural Science Foundation of China(No.41930533)the Taishan Scholars Project Funding(No.TS20190963)the Senior User Project of R/V KexueCenter for Ocean Mega-Science,Chinese Academy of Sciences。
文摘Seamount is a unique deep-sea ecosystem widely distributed in the world.Its biodiversity is vibrant due to its specific geographical and hydrological conditions.However,the diversity and features of foraminifera in such an environment have rarely been studied.We extracted environmental DNA(eDNA)in sedime nts and amplified the partial small subunit ribo somal DNA(SSU rDNA)of fo raminife ra to understand the foraminiferal diversity from four sites in Magellan Seamount(Western Pacific Ocean).Partial S SU rDNA sequencing was conducted and 912979 foraminiferal reads were obtained and gathered into 266 operational taxonomic units(OTUs).In the available dataset,a high proportion of rare OTUs and low identity OTUs in each studied sample showed that the Magellan Seamount foraminiferal community might have a high genetic novelty.The relative abundance of foraminifera varied between replicates probably due to the existence of bias in amplification process and patchiness of the deep-sea floor.It showed that the Magellan Seamount has a relatively high benthic foraminiferal diversity characterized mainly by monothalamiids(76.37%of total reads)in association with rotaliids(19.03%of total reads),including planktic foraminiferal sequences(38.58%of rotaliids;7.36%of total reads).The remaining reads were assigned to miliolids(0.83%of total reads)and textulariids(0.66%of total reads),and 3.11%of total reads are unassigned to a specific family.The co mparative analysis with foraminiferal assemblage s from coastal and deep-sea environme nts indicated that seamounts could aggregate species from a nearby deep-sea.
基金the National Natural Science Foundation of China(Nos.91858206,41876040)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22050101,XDB42020302)+1 种基金the Taishan Scholars Program of Shandong Province(No.tsqn201909157),Senior User Project of R/V Kexue(No.KEXUE2018G09)the Laboratory for Marine Geology,Qingdao National Laboratory for Marine Science and Technology(No.MGQNLMTD201806)。
文摘The alkaline oceanic island basalts(OIBs)with under-saturated SiO2 and high contents of CaO and alkaline are usually attributed to mantle sources different from typical tholeiitic OIBs.Based on the results of high pressure and temperature experiment study,the genesis of silica under-saturated alkaline basaltic melts could be explained by the role of CO2,thus,the genetic relationship of alkaline basalts with CO2 has become a topic of relevance because it is closely related to the deep carbon cycle.The Magellan Seamount chain in the West Pacific Seamount Province has wide distribution of alkali basalts.For the first time,we collected alkaline basalt samples from the Kocebu Seamount of the Magellan Seamount chain and found that magmatic apatites widely occur in the less evolved volcanic rock samples,and the high contents of phosphorus should be a feature of the alkaline OIBs of the Magellan Seamounts.Compared with typical OIBs,these alkaline volcanic rocks have higher CaO and P2O5,lower SiO2 content,negative anomaly of high field strength elements(HFSEs),more distinctly negative anomaly of potassium(K)and the ubiquity of titanaugite,indicating a CO2-rich mantle source.Based on the relatively high K2O and TiO2 contents and La/Yb ratio and low MgO content of these alkaline rocks,we suggest that the volcanic rocks of the Magellan Seamounts are originated from carbonated eclogites derived possibly from ancient subducted altered oceanic crust.
基金partially supported by the National Basic Research Program of China(973 Program,Grant Nos.2014CB845800 and 2013CB834900)the National Natural Science Foundation of China(Grant Nos.11322328,11433009,11673068 and 11603076)+4 种基金the Youth Innovation Promotion Association(2011231)the Key Research Program of Frontier Sciences(QYZDBSSW-SYS005)the Strategic Priority Research Program“The Emergence of Cosmological Structures”(Grant No.XDB09000000)of the Chinese Academy of Sciencesthe Natural Science Foundation of Jiangsu Province(Grant No.BK20161096)the Guangxi Key Laboratory for Relativistic Astrophysics
文摘A conservative constraint on the rest mass of the photon can be estimated under the assump- tion that the frequency dependence of dispersion from astronomical sources is mainly contributed by the nonzero photon mass effect. Photon mass limits have been set earlier through the optical emissions of the Crab Nebula pulsar, but we demonstrate that these limits can be significantly improved with the dispersion measure （DM） measurements of radio pulsars in the Large and Small Magellanic Clouds. The combination of DM measurements of pulsars and distances of the Magellanic Clouds provides a strict upper limit on the photon mass as low as mγ≤2.0 ～ 10-45 g, which is at least four orders of magnitude smaller than the constraint from the Crab Nebula pulsar. Although our limit is not as tight as the current best result （～ 10-47 g） from a fast radio burst （FRB 150418） at a cosmological distance, the cosmological origin of FRB 150418 remains under debate; and our limit can reach the same high precision of FRB 150418 when it has an extragalactic origin （ ～10-45 g）.
文摘The 80 high-mass X-ray binary （HMXB） pulsars that are known to reside in the Magellanic Clouds （MCs） have been observed by the XMM-Newton and Chandra X-ray telescopes on a regular basis for 15 years, and the XMM-Newton and Chandra archives contain nearly complete information about the duty cycles of the sources with spin periods Ps 〈 100 s. We have reprocessed the archival data from both observatories and we combined the output products with all the published observations of 31 MC pulsars with Ps 〈 100 s in an attempt to investigate the faintest X-ray emission states of these objects that occur when accretion to the polar caps proceeds at the smallest possible rates. These states determine the so-called propeller lines of the accreting pulsars and yield information about the magnitudes of their surface magnetic fields. We have found that the faintest states of the pulsars segregate into five discrete groups which obey to a high degree of accuracy the theoretical relation between spin period and X-ray luminosity. So the entire population of these pulsars can be described by just five propeller lines and the five corresponding magnetic moments （0.29, 0.53, 1.2, 2.9 and 7.3, in units of 1030 G cma）.
