Origin of power-law X-ray emission in the steep power-law state of X-ray binaries

We present a new explanation for the origin of the steep power-law(SPL) state of X-ray binaries.The power-law component of X-ray emission is the synchrotron radiation of relativistic electrons in highly magnetized compact spots orbiting near the inner stable circular orbit of a black hole.It has a hard spectrum that extends to above MeV energies,which is determined by the electron acceleration rate.These photons are then down-scattered by the surrounding plasma to form an observed steep spectrum.We discuss ...     

Panel positioning error and support mechanism for a 30-m THz radio telescope

A 30-m TeraHertz(THz) radio telescope is proposed to operate at 200 μm with an active primary surface.This paper presents sensitivity analysis of active surface panel positioning errors with optical performance in terms of the Strehl ratio.Based on Ruze's surface error theory and using a Monte Carlo simulation,the effects of six rigid panel positioning errors,such as piston,tip,tilt,radial,azimuthal and twist displacements,were directly derived.The optical performance of the telescope was then evaluated usi...     

External photon fields in Fermi bright blazars

The external Compton(EC) model is used to study the high energy emission of some blazars,in which the external photon field is considered to dominate inverse Compton radiation. We explore the properties of the external photon field through analyzing the FERMI LAT bright AGN sample within three months of the start of operations in sky-survey mode. In the sample,assuming the high energy radiation of low synchrotron peaked blazars is from the EC process,we find that the external photon parameter Uext/νext may ...     

Stellar kinematics and populations out to 1.5 effective radii in the elliptical galaxy NGC 4636

We present high quality long slit spectra along the major and minor axes out to 1.5 effective radii of the massive galaxy NGC 4636 taken by the Hobby-Eberly Telescope. Using the Fourier Correlation Quotient method,we measured the stellar line-of-sight velocity distribution along the axes. Furthermore,six Lick/IDS indices(Hβ,Mgb,Fe5015,Fe5270,Fe5335,Fe5406) are derived from the clean spectrum. By comparing the measured absorption line strengths with the predictions of Simple Stellar Population(SSP) models,we...     

The effects of BCGs on the statistics of large-separation lensed quasars by clusters

We study the statistics of large-separation multiply-imaged quasars lensed by clusters of galaxies.In particular,we examine how the observed brightest cluster galaxies (BCGs) affect the predicted numbers of wide-separation lenses.We model the lens as an NFW-profiled dark matter halo with a truncated singular isothermal sphere to represent the BCG in its center.We mainly make predictions for the Sloan Digital Sky Survey Quasar Lens Search (SQLS) sample from the Data Release 5 (DR5) in two standard ΛCDM cosmo...     

The prediction method of similar cycles

The concept of degree of similarity(η),is proposed to quantitatively describe the similarity of a parameter(e.g.the maximum amplitude Rmax)of a solar cycle relative to a referenced one,and the prediction method of similar cycles is further developed.For two parameters,the solar minimum(Rmin)and rising rate(βa),which can be directly measured a few months after the minimum,a synthesis degree of similarity(ηs)is defined as the weighted-average of theηvalues around Rmin and βa,with the weights given by the coef...     

Lensing clusters of galaxies in the SDSS-Ⅲ

We identify new strong lensing clusters of galaxies from the Sloan Digital Sky Survey III (SDSS DR8) by visually inspecting color images of a large sample of clusters of galaxies. We find 68 new clusters showing giant arcs in addition to 30 known lensing systems. Among 68 cases, 13 clusters are almost certain lensing systems with tangential giant arcs, 22 clusters are probable and 31 clusters are possible lensing systems. We also find two exotic systems with blue rings. The giant arcs have angular separatio...     

The mini-QSO's contribution to cosmic reionization

By employing an improved simulation of the evolution of black holes(BHs)based on the merger tree of dark matter halos,we explore the relationship between the central BH mass Mbh and velocity dispersion σflat high redshift z≥6 and quantify the mini-QSO's(with BH mass M=200-105M)contribution to cosmic reionization.The simulation demonstrates how seed BHs migrate onto the MBH-σ* relation by merging with each other and accreting gas at z≥6:1.The correlation between BHs and their host halos increases as the BHs ...     

第十七批天文学名词的推荐译名

中国天文学会名词审定委员会从1985年起开始在<天文学进展>发表天文学名词的推荐译名,到2009年已公布16批共2536个名词.现再推荐第17批114个名词,其中大多数是近年出现的天文学新词.希望读者在使用过程中对译名提出改进意见.     

Interstellar Refractive Scintillation and Intraday Polarization Angle Swings

Intraday polarization angle swings of ~180° observed in two sources (QSO 0917+624 and QSO 1150+812) are discussed in the framework of refractive interstellar scintillation by a continuous interstellar medium. Model-fits to the I-, Q- and U- light curves were made for both sources. It is shown that for the case of 0917+624 both the intraday intensity variations and the polarization angle swing of ~180° could be explained consistently in