We present a comprehensive analysis of AstroSat/LAXPC data of the second spin-up and second spin-down phases of the persistent X-ray pulsar 4U 1626-67.Flares followed by a broad dip are detected in the spin-up observa...We present a comprehensive analysis of AstroSat/LAXPC data of the second spin-up and second spin-down phases of the persistent X-ray pulsar 4U 1626-67.Flares followed by a broad dip are detected in the spin-up observations.The pulse profiles changed from a shoulder-like structure to a broad sinusoidal shape as the source underwent a torque reversal from spin-up to spin-down.Energy-resolved pulse profiles in lower energies showed a double-horned profile in the spin-up state and a flat top with multiple peaks in the spin-down state.Regardless of the torque state,the pulse profiles exhibit a broad single-peaked shape at higher energies.The observation in the spin-down era is characterized by the presence of a prominent QPO at 46.5±1.0 mHz frequency.The QPO rms and center frequency show a correlation with energy.Spin-up and spin-down states show a difference in the shape of the power density spectrum.After the torque reversal,a gradual flux drop and the hardening of the spectra were observed.The difference in the shape of the pulse profiles and the presence and absence of QPOs can be explained by the change in accretion flow geometry of the pulsar,from pencil-beam to fan-beam,between spin-down and spin-up states.展开更多
目的探讨R4U平面区域划分腹腔镜胆囊切除术(LC)与壶腹部技术(IT)LC的治疗效果。方法回顾性分析2021年6月至2021年12月安徽理工大学第一附属医院实施LC的196例患者,按照手术方式分成R4U组(n=95)和IT组(n=101),比较两组术中出血量、手术...目的探讨R4U平面区域划分腹腔镜胆囊切除术(LC)与壶腹部技术(IT)LC的治疗效果。方法回顾性分析2021年6月至2021年12月安徽理工大学第一附属医院实施LC的196例患者,按照手术方式分成R4U组(n=95)和IT组(n=101),比较两组术中出血量、手术时间、术后胆红素和肝功能、术后住院时间,以及手术中转开腹率、重要器官(胆道或肠道)损伤率的差异。结果两组在术中出血量、手术时间、术后胆红素和肝功能、术后住院时间的比较,差异均无统计学意义(P>0.05)。但R4U组和IT组在中转开腹率[1例(1.05%)vs 9例(8.91%)]、重要器官损伤率[0 vs 6例(5.94%)]方面,组间存在统计学差异(P<0.05)。结论R4U平面区域划分技术和壶腹部技术均是LC的有效方法,R4U区域划分技术是对关键安全视野(CVS)理念的补充和延伸,值得临床推广。展开更多
Using data from the Large Area X-ray Proportional Counter(LAXPC)on the AstroSat satellite,we observed Type-1 thermonuclear X-ray bursts from the low mass X-ray binary neutron star 4 U 1323-62.Observations of 4 U 1323-...Using data from the Large Area X-ray Proportional Counter(LAXPC)on the AstroSat satellite,we observed Type-1 thermonuclear X-ray bursts from the low mass X-ray binary neutron star 4 U 1323-62.Observations of 4 U 1323-62 that were carried out during the performance verification phase of the AstroSat satellite indicated six thermonuclear X-ray bursts in a total effective exposure of^49.5 ks for about two consecutive days.Recurrence time of the detected thermonuclear bursts is in accordance with the orbital period of the source,~9400 s.Moreover,the light curve of 4 U 1323-62 revealed the presence of two dips.We present the results from time-resolved spectroscopy performed during all of the six X-ray bursts and also report the detection of a known low frequency quasi-periodic oscillation(LFQPO)at^1 Hz from the source.However,any evidence of kilohertz QPO was not found.We have shown the burst profile at different energy ranges.Assuming a distance of 10 kpc,we observed a mean flux of^1.8×10^-9 erg cm^2 s^-1.The radius of the blackbody is found to be highly consistent with the blackbody temperature and the blackbody flux of the bursts.展开更多
Results on timing and spectral properties of the Be/X-ray binary pulsar 3A 0726-260(4U 0728-25)are presented.The binary was observed on 2016 May 6-7 with the Large Area X-ray Proportional Counter(LAXPC)and Soft X-ray ...Results on timing and spectral properties of the Be/X-ray binary pulsar 3A 0726-260(4U 0728-25)are presented.The binary was observed on 2016 May 6-7 with the Large Area X-ray Proportional Counter(LAXPC)and Soft X-ray Telescope(SXT)instruments onboard the AstroSat satellite.During this observation,the source was in non-flaring persistent state at a flux level of^8.6±0.3×10^-11 erg cm^-2 s^-1in 0.4-20 keV.Strong X-ray pulsations with a period of 103.144±0.001 s are detected in 0.3-7 keV with the SXT and in 3-40 keV with the LAXPC.The pulse profile is energy dependent,and there is an indication that the pulse shape changes from a broad single pulse to a double pulse at higher energy.At energies above20 keV,we report the first time detection of pulsation period 103.145±0.001 s and the double peaked pulse profile from the source.The energy spectrum of the source is derived from the combined analysis of the SXT and LAXPC spectral data in 0.4-20 keV.The best spectral fit is obtained by a power law model with a photon index(1.7±0.03)with high energy spectral cut-off at 12.9±0.7 keV.A broad iron line at^6.3 keV is detected in the energy spectrum.We briefly discuss the implications of these results.展开更多
A circumstellar corona is proposed to explain a strange quark-cluster star during an accretion phase, which could be essential for understanding the observa- tions of the puzzling symbiotic X-ray system 4U 1700＋24. T...A circumstellar corona is proposed to explain a strange quark-cluster star during an accretion phase, which could be essential for understanding the observa- tions of the puzzling symbiotic X-ray system 4U 1700＋24. The state of cold matter at supranuclear density is still an important matter of debate, and one of the con- sequences of a strange star acting as a pulsar is the self-bound phenomenon on the surface, which makes extremely low-mass compact objects unavoidable. In principle, both the redshifted O VIII Ly-c~ emission line and the change in the blackbody radi- ation area could naturally be understood if 4U 1700＋24 is a low-mass quark-cluster star which exhibits wind accretion.展开更多
The anomalous X-ray pulsar 4U 0142＋61 has been studied with obser- vations from INTEGRAL. The hard X-ray spectrum in the range 18-500 keV for 4U 0142＋61 was derived using nearly nine years of INTEGRAL/IBIS data. We ...The anomalous X-ray pulsar 4U 0142＋61 has been studied with obser- vations from INTEGRAL. The hard X-ray spectrum in the range 18-500 keV for 4U 0142＋61 was derived using nearly nine years of INTEGRAL/IBIS data. We ob- tained the average hard X-ray spectrum of 4U 0142＋61 with all available data. The spectrum of 4U 0142＋61 can be fitted with a power law that includes an exponen- tial high energy cutoff. This average spectrum is well fitted by a power law with r ,~ 0.51 ± 0.11 plus a cutoff energy at 128.6 ± 17.2 keV. The hard X-ray flux of the source from 20-150 keV showed no significant variations （within 20%） from 2003- 2011. The spectral profiles have some variability over the nine years such that the photon index varies from 0.3-1.5 and the cutoff energies from 110-250 keV. The de- tection of the high energy cutoff around 130 keV shows some constraints on the radia- tion mechanisms of magnetars and possibly probes the differences between magnetar and accretion models for this special class of neutron stars. Future HXMTobservations could provide stronger constraints on the hard X-ray spectral properties of this source and other magnetar candidates.展开更多
基金financial support from ISRO(Sanction Order:No.DS_2B-13013(2)/3/2021-Sec.2)。
文摘We present a comprehensive analysis of AstroSat/LAXPC data of the second spin-up and second spin-down phases of the persistent X-ray pulsar 4U 1626-67.Flares followed by a broad dip are detected in the spin-up observations.The pulse profiles changed from a shoulder-like structure to a broad sinusoidal shape as the source underwent a torque reversal from spin-up to spin-down.Energy-resolved pulse profiles in lower energies showed a double-horned profile in the spin-up state and a flat top with multiple peaks in the spin-down state.Regardless of the torque state,the pulse profiles exhibit a broad single-peaked shape at higher energies.The observation in the spin-down era is characterized by the presence of a prominent QPO at 46.5±1.0 mHz frequency.The QPO rms and center frequency show a correlation with energy.Spin-up and spin-down states show a difference in the shape of the power density spectrum.After the torque reversal,a gradual flux drop and the hardening of the spectra were observed.The difference in the shape of the pulse profiles and the presence and absence of QPOs can be explained by the change in accretion flow geometry of the pulsar,from pencil-beam to fan-beam,between spin-down and spin-up states.
文摘目的探讨R4U平面区域划分腹腔镜胆囊切除术(LC)与壶腹部技术(IT)LC的治疗效果。方法回顾性分析2021年6月至2021年12月安徽理工大学第一附属医院实施LC的196例患者,按照手术方式分成R4U组(n=95)和IT组(n=101),比较两组术中出血量、手术时间、术后胆红素和肝功能、术后住院时间,以及手术中转开腹率、重要器官(胆道或肠道)损伤率的差异。结果两组在术中出血量、手术时间、术后胆红素和肝功能、术后住院时间的比较,差异均无统计学意义(P>0.05)。但R4U组和IT组在中转开腹率[1例(1.05%)vs 9例(8.91%)]、重要器官损伤率[0 vs 6例(5.94%)]方面,组间存在统计学差异(P<0.05)。结论R4U平面区域划分技术和壶腹部技术均是LC的有效方法,R4U区域划分技术是对关键安全视野(CVS)理念的补充和延伸,值得临床推广。
基金support from the Indian Space Research Organization(ISRO)and AstroSat science support cell in various aspects of instrument building,testing,software development and mission operation during the payload verification phase。
文摘Using data from the Large Area X-ray Proportional Counter(LAXPC)on the AstroSat satellite,we observed Type-1 thermonuclear X-ray bursts from the low mass X-ray binary neutron star 4 U 1323-62.Observations of 4 U 1323-62 that were carried out during the performance verification phase of the AstroSat satellite indicated six thermonuclear X-ray bursts in a total effective exposure of^49.5 ks for about two consecutive days.Recurrence time of the detected thermonuclear bursts is in accordance with the orbital period of the source,~9400 s.Moreover,the light curve of 4 U 1323-62 revealed the presence of two dips.We present the results from time-resolved spectroscopy performed during all of the six X-ray bursts and also report the detection of a known low frequency quasi-periodic oscillation(LFQPO)at^1 Hz from the source.However,any evidence of kilohertz QPO was not found.We have shown the burst profile at different energy ranges.Assuming a distance of 10 kpc,we observed a mean flux of^1.8×10^-9 erg cm^2 s^-1.The radius of the blackbody is found to be highly consistent with the blackbody temperature and the blackbody flux of the bursts.
基金ISRO for providing funding supportmade use of softwares obtained through the HEASARC Online Service,provided by NASA/GSFC,in support of NASA High Energy Astrophysics Programs。
文摘Results on timing and spectral properties of the Be/X-ray binary pulsar 3A 0726-260(4U 0728-25)are presented.The binary was observed on 2016 May 6-7 with the Large Area X-ray Proportional Counter(LAXPC)and Soft X-ray Telescope(SXT)instruments onboard the AstroSat satellite.During this observation,the source was in non-flaring persistent state at a flux level of^8.6±0.3×10^-11 erg cm^-2 s^-1in 0.4-20 keV.Strong X-ray pulsations with a period of 103.144±0.001 s are detected in 0.3-7 keV with the SXT and in 3-40 keV with the LAXPC.The pulse profile is energy dependent,and there is an indication that the pulse shape changes from a broad single pulse to a double pulse at higher energy.At energies above20 keV,we report the first time detection of pulsation period 103.145±0.001 s and the double peaked pulse profile from the source.The energy spectrum of the source is derived from the combined analysis of the SXT and LAXPC spectral data in 0.4-20 keV.The best spectral fit is obtained by a power law model with a photon index(1.7±0.03)with high energy spectral cut-off at 12.9±0.7 keV.A broad iron line at^6.3 keV is detected in the energy spectrum.We briefly discuss the implications of these results.
基金Supported by the National Natural Science Foundation of China
文摘A circumstellar corona is proposed to explain a strange quark-cluster star during an accretion phase, which could be essential for understanding the observa- tions of the puzzling symbiotic X-ray system 4U 1700＋24. The state of cold matter at supranuclear density is still an important matter of debate, and one of the con- sequences of a strange star acting as a pulsar is the self-bound phenomenon on the surface, which makes extremely low-mass compact objects unavoidable. In principle, both the redshifted O VIII Ly-c~ emission line and the change in the blackbody radi- ation area could naturally be understood if 4U 1700＋24 is a low-mass quark-cluster star which exhibits wind accretion.
基金Supported by the National Natural Science Foundation of China
文摘The anomalous X-ray pulsar 4U 0142＋61 has been studied with obser- vations from INTEGRAL. The hard X-ray spectrum in the range 18-500 keV for 4U 0142＋61 was derived using nearly nine years of INTEGRAL/IBIS data. We ob- tained the average hard X-ray spectrum of 4U 0142＋61 with all available data. The spectrum of 4U 0142＋61 can be fitted with a power law that includes an exponen- tial high energy cutoff. This average spectrum is well fitted by a power law with r ,~ 0.51 ± 0.11 plus a cutoff energy at 128.6 ± 17.2 keV. The hard X-ray flux of the source from 20-150 keV showed no significant variations （within 20%） from 2003- 2011. The spectral profiles have some variability over the nine years such that the photon index varies from 0.3-1.5 and the cutoff energies from 110-250 keV. The de- tection of the high energy cutoff around 130 keV shows some constraints on the radia- tion mechanisms of magnetars and possibly probes the differences between magnetar and accretion models for this special class of neutron stars. Future HXMTobservations could provide stronger constraints on the hard X-ray spectral properties of this source and other magnetar candidates.
