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...     

Binary population synthesis study of the supersoft X-ray phase of single degenerate type Ia supernova progenitors

In the single degenerate(SD) scenario for type Ia supernovae(SNe Ia) ,a mass-accreting white dwarf is expected to experience a supersoft X-ray source(SSS) phase. However,some recent observations showed that the expected number of massaccreting WDs is much lower than that predicted from theory,regardless of whether they are in spiral or elliptical galaxies. In this paper,we performed a binary population synthesis study on the relative duration of the SSS phase to their whole massincreasing phase of WDs leadi...     

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...     

Multiband fitting to three long GRBs with Fermi/LAT data:structured ejecta sweeping up a density-jump medium

We present broadband (radio,optical,X-ray and GeV) fits to the afterglow light curves and spectra of three long-duration gamma-ray bursts (GRBs 080916C,090902B,and 090926A) detected by the Gamma-Ray Burst Monitor and Large Area Telescope (LAT) instruments on the Fermi satellite.Using the observed broadband data,we study the origin of the high energy emission,and suggest that the early-time GeV emission and the late-time radio,optical,and X-ray afterglows can be understood as being due to synchrotron emissio...     

Nonlinear time series analysis of the light curves from the black hole system GRS 1915+105

GRS 1915+105 is a prominent black hole system exhibiting variability over a wide range of time scales and its observed light curves have been classified into 12 temporal states. Here we undertake a complete analysis of these light curves from all the states using various quantifiers from nonlinear time series analysis, such as the correlation dimension (D2), the correlation entropy (K2), singular value decomposition (SVD) and the multifractal spectrum (f(α) spectrum). An important aspect of our analysis is ...     

The optical/ultraviolet excess of isolated neutron stars in the resonant cyclotron scattering model

X-ray dim isolated neutron stars are peculiar pulsar-like objects,characterized by their Planck-like spectrum.In studying their spectral energy distributions,optical/ultraviolet(UV) excess is a long standing problem.Recently Kaplan et al.measured the optical/UV excess for all seven sources,which is understandable in the resonant cyclotron scattering(RCS) model previously addressed.The RCS model calculations show that the RCS process can account for the observed optical/UV excess for most sources.The ?at spe...     

Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies

We present an efficient,robust computational method for modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies.With appropriate mathematical treatments,the apparent numerical difficulties associated with singularities in computing elliptic integrals are completely removed.Using a boundary element discretization procedure,the governing equations are transformed into a linear algebra matrix equation that can be solved by straightforward Gauss elimination in one step without further ...     

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...     

The Origin of Paleokarst in the Huanglong Formation of the Eastern Sichuan Basin: Evidence from δ13C, δ18O and 87Sr/86Sr

Karst rocks from the Huanglong Formation exposed at the margin of the Eastern Sichuan Basin can be divided into four types:slightly corroded, moderately corroded porous, intensely corroded brecciated and intensely corroded and replaced secondary calcic karstic rocks. The carbon, oxygen and strontium isotope compositions of the various karst rocks are analyzed systematically and compared to rocks without karst corrosion. The results indicate that(1) the Huanglong Formation in the eastern Sichuan Basin was a restricted bay supplied and controlled by freshwater in which mudmicrite and mud-dolomicrite exhibit low δ13C and δ18O values and high 87Sr/86 Sr ratios;(2) all types of karstic rocks in the paleokarst reservoirs of the Huanglong Formation in the research area are affected by atmospheric freshwater with the δ13C and δ18O values and 87Sr/86 Sr ratios in the original formation approaching those of atmospheric freshwater, which reflects ancient hydrological conditions, fluid properties, isotopic source and the fractionation effect;(3) the intensely corroded and replaced secondary limestone is affected by a variety of diagenetic fluids, often reflected by δ13C and δ18O values, while the 87Sr/86 Sr ratios exhibit the strong degree of the corrosion;(4) after comparing the 87Sr/86 Sr ratios of each type of karst rock, the diagenetic fluids are determined to be mainly atmospheric freshwater, and depending on the strength of corrosion, and the low 87Sr/86 Sr ratio fluids in the layer will participate in the karst process. The carbon, oxygen, and strontium isotopes of different karstic reservoirs can provide meaningful geochemical information for forecasting and evaluating the development and distribution rules of the Huanglong Formation at the margin of the eastern Sichuan Basin in time and space.     

Experimental Set-up for Determining Soil Water Retention Curves for Granular Soils During Drying

Abstract: Soil water retention curves (SWRCs) provide an important means of describing the response of unsaturated soils during drying / wetting processes in terms of variations of degree of saturation, water content or void ratio with suction. A key consideration in generating these curves is how to measure the suction. Frequently the filter paper technique is adopted, especially when high suctions are developed, e.g. with plastic clays. As each measurement takes at least a week with this technique, it can take months or years to generate a full SWRC in drying and wetting. Developments in laboratory tensiometers now allow matrix suctions up to about 1.5 MPa to be measured. With such a device it is possible to develop SWRCs for granular soils such as silts and clays in hours or days by continuous measurement. This paper describes an experimental set-up that was developed to measure changes in volume, water content and matrix suction during drying of three granular soils. Limitations of the apparatus and usefulness of the curves are discussed.