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Simulation of the in-flight calibration of the collimator alignment and PSF for HXMT

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 47-50页

作者： XIONG ShaoLin,LI XinQiao,QU JinLu & LU FangJun key Laboratory for particle astrophysics,{3.,chinese academy of sciences(CAS),beijing 100049,china 1. key Laboratory for particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences (CAS) Beijing 100049 China

The Hard X-ray Modulation Telescope(HXMT) is an X-ray astronomical satellite in 1-250 keV,consisting of three collimated *** present the in-flight calibration approach of the collimator alignment and Point Spread Function(PSF) for HXMT,using both the direct fitting method and the imaging *** to observational simulations of the Crab Nebula,we find that these two methods produce almost the same calibration accuracy of the alignment,and with a one-day scanning observation,the alignment can be calibrated to better than 0.45' and 0.1' along the wide and narrow directions of the Field of View(FOV) for a detector module,which corresponds to a localization accuracy of better than 0.1' and meets the scientific requirement.

关键词： HXMT alignment PSF calibration

SVOM gamma ray monitor

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 40-42页

作者： DONG YongWei,WU BoBing,LI YanGuo,ZHANG YongJie & ZHANG ShuangNan key Laboratory of particle astrophysics,{3.,chinese academy of sciences,beijing 100049,china 1. key Laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

The space-based multi-band astronomical Variable Object Monitor(SVOM) mission is dedicated to the detection,localization and broad-band study of gamma-ray bursts(GRBs) and other high-energy transient *** gamma ray monitor(GRM) onboard is designed to observe GRBs up to 5 *** this instrument,one of the key GRB parameters,Epeak,can be easily measured in the hard X-ray *** can achieve a detection rate of 100 GRBs per year which ensures the scientific output of SVOM.

关键词： gamma-ray burst Epeak triple phoswich

Hard X-ray lags of Cygnus X-1 on short timescales

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 150-152页

作者： JIN Jing1,LU Yu2,3.QU JinLu2 & LI TiPei1,2 1 Department of Engineering physics & Center for astrophysics,Tsinghua University,beijing 100084,{3. 2 key Laboratory of particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,{3. 3.Graduate University of chinese academy of sciences,beijing 100049,{3. 1. Department of Engineering physics & Center for astrophysics Tsinghua University Beijing 100084 China2. Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China3. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Calculating the time lags over different timescales using the cross-correlation technique may lead to a biased estimate of small *** a timescale for lightcurve binning,we propose to subtract the local average instead of the global average during the cross-correlation,in order to filter variations on timescales larger than the bin *** new method allows us to make an unbiased estimate of the time lags using RXTE/PCA data on timescales as small as-5 ms,where the Fourier technique becomes *** calculate the time lag spectra of Cygnus X-1 at different spectral states with the new method,and find that the source appears to have similar X-ray lags on small timescales independent of its spectral states.

关键词： spectral lags Cygnus X-1 data analysis

Light collection of the POLAR detector

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 43-46页

作者： DONG YongWei,LI YanGuo,WU BoBing,ZHANG YongJie & ZHANG ShuangNan key Laboratory of particle astrophysics,{3.,chinese academy of sciences,beijing 100049,china 1. key Laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

POLAR is a compact polarimeter dedicated to measuring the polarization of GRBs between 50-3.0 *** light collection of 200 mm×6 mm×6 mm plastic bars has been simulated and optimized in order to get uniform response to X-rays at different points along one single *** to the Monte Carlo results,the amplitude uniformity strongly depends on the level of polishing of the scintillator surface and the covering.A uniformity of 89% is achieved with a prototype constructed by a non position-sensitive PMT and an array of 4×4 bars.

关键词： plastic scintillator light collection gamma-ray burst polarimeter

Observation constraints of the hard X-ray modulation telescope HXMT

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 31-35页

作者： LU Yu1,2,ZHANG WenZhao3.QU JinLu1,SONG LiMing1,GAO Jian3.ZHANG HongMei4 & OU Ge4 1 key Laboratory of particle astrophysics,{3.,chinese academy of sciences,beijing 100049,china 2 Graduate University of chinese academy of sciences,beijing 100049,china 3.Department of Astronomy,beijing Normal University,beijing 100875,china 4 Computing Center,{3.,chinese academy of sciences,beijing 100049,china 1. key Laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China 2. Graduate University of chinese academy of sciences Beijing 100049 China 3. Department of Astronomy Beijing Normal University Beijing 100875 China 4. Computing Center Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

The hard X-ray modulation telescope HXMT is a low orbit X-ray space telescope whose main science goals are to accomplish a hard X-ray all sky survey and to study timing and spectral characteristics of X-ray *** has three kinds of science instruments:the high energy X-ray detector(HE),the medium energy X-ray detector(ME) and the low energy X-ray detector(LE).The observation schedule of HXMT is a key to achieving the science goal of HXMT,and the analysis of the observation constraints is one of the first tasks in making the observation *** paper analyzes how the observation constraints influence the sky visibility and the visible time distribution of X-ray sources and discusses the schedule strategy with regard to the observation constraints.

关键词： HXMT observation constraints sky visibility

The rms-flux relation of Cyg X-2 in the horizontal branch

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中国科学：物理学、力学、天文学英文版 2010年第S1期53卷 86-90页

作者： LI ZhiBing,LEI YaJuan,QU JinLu,ZHANG Shu & SONG LiMing key Laboratory for particle astrophysics,{3.,chinese academy of sciences(CAS),beijing 100049,china chinese Acad Sci Inst High Energy Phys Key Lab Particle Astrophys Beijing 100049 Peoples R China

We have investigated the relation between the root mean square(rms) variability and the X-ray flux(rms-flux relation) of the Z source Cyg X-2,and as well the energy dependence based on the Rossi X-ray Timing Explorer(RXTE) *** currently focus on the horizontal branch(HB),due to the negative correlation in flux of the soft and the hard *** rms-flux correlation has energy dependence as follows:positive at hard X-rays(above 10 keV) but negative at soft X-rays(below 10 keV).This provides a feature different from the previous one,and may be suggestive of different origins of X-rays below and above 10 ***,the overall spectrum can be well fitted with a model consisting of a blackbody and Comptonization components,but the fitting results do not reveal any features around 10 keV that could account for such a change in the rms-flux relation.

关键词： accretion accretion disk—binaries:close-stars:individual(Cygnus X-2)-X-rays:binaries

Effects of cosmological constant on motion of UHECR particles

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Science china(physics,Mechanics & Astronomy) 2005年第1期48卷 44-56页

作者： CHEN Shaoxia & CHANG Zhe institute of high energy physics, chinese academy of sciences, beijing 10003., {3. Graduate School of chinese academy of sciences, beijing 10003., {3. institute of high energy physics Chinese Academy of Sciences Beijing 100039 China Graduate School Chinese Academy of Sciences Beijing 100039 China

Recent astronomical observations manifest that about two-thirds of the whole energy in the Universe is contributed by a small positive cosmological constant A (> 0). Then, an asymptotically de Sitter spacetime is premised naturally. However, physics in the de Sitter spacetime is very different from that in the Minkowski spacetime. As the first step, a covariant formalism of the kinematics in the de Sitter spacetime is presented here. By solving exactly the equations of motion for a field, we obtain the dispersion relation of a free particle. It is noticed that the dispersion relation is dependent on the degree of freedom of angular momentum of the particle. We show the threshold anomaly of the ultra high energy cosmic ray disappears naturally in the framework of the de Sitter kinematics.

关键词： ultrahigh energy cosmic ray, cosmological constant, curved spacetime.

GRB 090423.Marking the death of a massive star at z=8.2

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 64-68页

作者： LIN Lin1,LIANG EnWei2 & ZHANG ShuangNan3.1 Department of physics and Center for astrophysics,Tsinghua University,beijing 100084,{3. 2 Department of physics,Guangxi University,Nanning 53.004,{3. 3.key Laboratory of particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,{3. Guangxi Univ Dept Phys Nanning 530004 Peoples R China Tsinghua Univ Dept Phys Beijing 100084 Peoples R China Tsinghua Univ Ctr Astrophys Beijing 100084 Peoples R China chinese Acad Sci Inst High Energy Phys Key Lab Particle Astrophys Beijing 100049 Peoples R China

GRB 090423.is the new high-z record holder of Gamma-ray bursts(GRBs) with *** present a detailed analysis of both the spectral and temporal features of GRB 090423.observed with Swift/BAT and Fermi/*** find that the T90 observed with BAT in the 15-150 keV band is 13.2 s,corresponding to-1.4 s at z=*** once again gives rise to the issue of whether the progenitors of high-z GRBs are massive stars or mergers since the discovery of GRB 080913.at z=*** comparison with the T90 distribution in the burst frame of the current redshift-known GRB sample,we find that it is marginally grouped into the long group(Type II GRBs).The spectrum observed with both BAT and GBM is well fitted by a power-law with exponential cutoff,which yields an Ep=(50.4±7.0) *** event satisfies the Amati-relation well for Type II GRBs within their 3. uncertainty *** results indicate that this event would be produced by the death of a massive *** on the Amati-relation,we derive its distance modulus,which follows the Hubble diagram of the concordance cosmology model at a redshift of-8.2.

关键词： gamma-ray bursts high energy phenomenon cosmology

Temporal study of GRS 1915+105 with rms-flux relation:The importance of magnetic activities in the corona

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 120-124页

作者： HAN Dong1,ZHANG ShuangNan2 & SONG LiMing2 1 Department of Engineering physics & Center for astrophysics,Tsinghua University,beijing 100084,{3. 2 key Laboratory of particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,{3. 1. Department of Engineering physics & Center for astrophysics Tsinghua University Beijing 100084 China 2. key Laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

The rms-flux relations for some observations of GRS 1915+105 are *** rms-flux relations of the light curves in only one state,state C or state A,can be described by the simple non-linear model provided Zhang;we thus interpret that such a linear relation reflects the relative importance of magnetic instability for X-ray emission in the corona of the system,compared to the thermal viscous instability for the X-ray emission in the accretion *** rms-flux relations for state B are very scattered,possibly because of the dominance of thermal viscous instability for the X-ray emission in the accretion *** complex rms-flux relations for the observations of transitions between two or three states are caused by the combination of the different rms-flux relations of these *** underlying physical processes are the combination of magnetic topology in the corona and thermal viscous instability in the accretion disk.

关键词： rms-flux relation data analysis GRS 1915+105 magnetic instability