Energy Dependence of Profile Width in Short Gamma-Ray Bursts

Using the high time-resolution and 64ms resolution data of the burst and transient source experiment,we performed an autocorrelation analysis of the energy dependence of burst pulse width in short gamma-ray bursts.A method free from potential cosmological effects has been proposed.This allows us to use a sample with a size comparable to that used for long and bright bursts.Our result shows that the profiles of short bursts exhibit a very good power-law between profile width and photon energy,with an index~-0.3.This result is consistent with a united origin of the bimodal distribution.

康普顿化的计算——推广的Kompaneets方程与Monte Carlo方法比较

在X射线天文学以及辐射物理学中,当硬X射线穿过“冷”的等离子体时所发生的Compton软化是一种重要的辐射转移过程。简要介绍推广的Kompaneets方程,该方程在hv《m_ec^2及kT_e《m_ec^2较宽松的条件下广泛成立,因此不仅能处理Compton硬化过程,而且也适用于Compton软化过程,后者在目前快速发展的X射线和γ射线天文学中十分重要。基于此方程,我们对天体物理中4种常见辐射谱(Gauss型发射谱线、黑体辐射谱、幂律辐射谱和热轫致辐射谱)在Compton软化情况下的港演化进行了数值求解,并同 Monte Carlo模拟结果做比较,证实了推广的 Kompaneets方程的正确性和有效性。最后指出此方程在X射线天文学和γ射线天文学中的重要意义和潜在应用。

The Inclination, Pitch Angle and Forbidden Radius of Spiral Arms of PGC 35105

We have studied some properties including surface brightness in the u, g, r, i, and z bands of the nearly face-on galaxy PGC 35105. By subtracting a model surface brightness distribution from the observed image we obtain the residual image that shows only the spiral arms freed from the contamination by the bulge. From this we measured the the inclination, pitch angle, and forbidden radius （identified with the innermost point of the arm） for each of the two arms; and that for each of the five observing bands. We found these three parameters are largely independent of the observing band.

A Possible Glitch of Gamma-Ray Pulsar Geminga?

Timing analyses of gamma-ray pulsar Geminga were made to check its rotating stability using released energetic gamma-ray experiment(EGRET)data.Phase motions of Geminga were found from EGRET data in 1995.Joint analysis of parameters searching and bootstrap testing showed that the parameters are getting worse when including EGRET data in 1995.Combination of these results may indicate that a small glitch of Geminga occurred in 1995.

Overall Evolution of Realistic Gamma-Ray Burst Remnant and Its Afterglow

Conventional dynamic model of gamma-ray burst remnants is found to be incorrect for adiabatic blastwaves during the non-relativistic phase.A new model is derived,which is shown to be correct for both radiative and adiabatic blastwaves during both ultra-relativistic and non-relativistic phases.Our model also takes the evolution of the radiative efficiency into account.The importance of the transition from the ultra-relativistic phase to the non-relativistic phase is stressed.

Two Different Burster Spatial Distributions of Gamma-Ray Bursts?

By using the first,second and third electronic burst and transcient source experiment catalogs,a joint analysis of spatial and temporal distributions and hardness ratios of gamma-ray bursts is performed.Turning point features at C_(max)/C_(min) ~6 are found.This probably indicates the existence of two components of burster population which have distinct spatial distributions.

Radiation and Vertical Structure of Slim Accretion Disk

The vertical structure of the disk should be specified in order to compare the theoretical model with the observed spectrum of active galactic nuclei.AH the existing calculations of vertical structure of the accretion disk were based on the standard model.In this paper the vertical structure of the slim disk is calculated,which may be suitable for wider ranges of parameters.The spectrum for higher accretion rate tends to the universal form Fv oc z/-1 and the universal cutoff energy,which is consistent with the self^similar solution for the case with a super-Eddington accretion rate.

Accretion properties of MAXI J1813-095 during its failed outburst in 2018

We present the results obtained from detailed timing and spectral studies of a black hole candidate MAXI J1813-095 using Swift,NICER,and NuSTAR observations during its 2018 outburst.The timing behavior of the source is mainly studied by examining NICER light curves in the 0.5−10 keV range.We did not find any signature of quasi-periodic oscillations in the power density spectra of the source.We carry out spectral analysis with a combined disk blackbody&power law model,and physical two-component advective flow(TCAF)model.From the combined disk blackbody&power-law model,we extracted thermal and non-thermal fluxes,photon index and inner disk temperature.We also find evidence for weak reflection in the spectra.We have tested the physical TCAF model on a broadband spectrum from NuSTAR and Swift/XRT.The parameters like mass accretion rates,the size of Compton clouds and the shock strength are extracted.Our result affirms that the source remained in the hard state during the entire outburst which indicates a‘failed’outburst.We estimate the mass of the black hole as 7.4±1.5M⊙from the spectral study with the TCAF model.We apply the LAOR model for the Fe K line emission.From this,the spin parameter of the black hole is ascertained as a^(∗)>0.76.The inclination angle of the system is estimated to be in the range of 28°−45°from the reflection model.We find the source distance to be∼6 kpc.

Scale Heights of Non-Edge-on Spiral Galaxies

We present a method of calculating the scale height of non-edge-on spiral galaxies, together with a formula for errors. The method is based on solving Poisson＇s equation for a logarithmic disturbance of matter density in spiral galaxies. We show that the spiral arms can not extend to inside the ＂forbidden radius＂ r0, due to the effect of the finite thickness of the disk. The method is tested by re-calculating the scale heights of 71 northern spiral galaxies previously calculated by Ma, Peng ＆ Gu. Our results differ from theirs by less than 9%. We also present the scale heights of a further 23 non-edge-on spiral galaxies.

Disk Thicknesses and Some Parameters of 108 Non-Edge-On Spiral Galaxies

We present disk thicknesses, some other parameters and their statistics of 108 nonedge-on spiral galaxies. The method for determining the disk thickness is based on solving Poisson＇s equation for a disturbance of matter density in three-dimensional spiral galaxies. From the spiral arms found we could obtain the pitch angles, the inclination of the galactic disk, and the position of the innermost point （the forbidden region with radius r0 to the galactic center） of the spiral arm, and finally the thickness.

Fusion Reaction of ^16O＋^14N and Its Implication for the Production of ^26Al in Explosive Oxygen Burning

We suggest that the fusion reaction ^16O＋^14N may be a new way to produce ^26Al in interstellar medium. Adopting different mixing modes, we investigate the impact on the production of ^26Al in explosive oxygen burning and find that the result is extremely sensitive to mixing mechanisms. In some cases, we obtain an encouraging result, for example, the greatest final abundance of ^26Al reaches 7.779×10^-6, which means that the explosive oxygen burning may be a new origin of ^26 Al.

Design and simulations for the detector based on DSSSD

The present paper describes the design and simulation results of a position-sensitive charged particle detector based on the Double Sided Silicon Strip Detector （DSSSD）. Also, the characteristics of the DSSSD and its testing result were are discussed. With the application of the DSSSD, the position-sensitive charged particle detector can not only give particle flux and energy spectra information and identify different types of charged particles, but also measure the location and angle of incident particles. As the detector can make multi-parameter measurements of charged particles, it is widely used in space detection and exploration missions, such as charged particle detection related to earthquakes, space environment monitoring and solar activity inspection.