Discovery of a double peaked Fe emission line in the Cloverleaf quasar H1413+117

Our spatial and spectral analysis of a recent deep Chandra observation of H1413+117 confirms a microlensing event in a previous Chandra observation of this object performed about 5 years earlier. We present constraints on the structure of H1413+117 based on the time‐scale of this microlensing event. The analysis of the combined spectrum of the images indicates the presence of two emission line peaks at rest‐frame energies of 5.35 keV and 6.32 keV and detected at the ≳97% and ≳99% confidence levels, respectively. The double peaked Fe emission is fit well with an accretion disk‐line model, however, the best‐fit accretion disk model parameters are neither well constrained nor unique. Another possible interpretation of the Fe emission is fluorescent Fe emission from the back‐side of the wind. Additional observations are required to constrain better the model parameters. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Amplification and variability of the AGN X‐ray emission due to microlensing

We consider the contribution of microlensing to the AGN Fe Kα line and X‐ray continuum amplification and variation. To investigate the variability of the line and X‐ray continuum, we studied the effects of microlensing on quasar X‐ray spectra produced by crossing of a microlensing pattern across a standard relativistic accretion disk. To describe the disk emission we used a ray tracing method considering both metrics, Schwarzschild and Kerr. We found that the Fe Kα and continuum may experience significant amplification by a microlensing event (even for microlenses of very small mass). Also, we investigate a contribution of microlensing to the X‐ray variability of high‐redshifted QSOs, finding that cosmologically distributed deflector may contribute significantly to the X‐ray variability of high‐redshifted QSOs (z > 2). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

含Mg矿物和玻璃中Mg的局部结构研究

本文用同步辐射的MgK-边X射线近边结构谱(XANES)研究了9种含Mg矿物的MgK-边特征谱,其谱的能量位置随着配位数的增加而增大;建立了含Mg矿物中Mgk-边的能量与Mg-O键距的关系CaMgSi2O6(Di)-NaAlSi3O8(Ab)玻璃中MgK-边XANES的能量和Mg-O的键长的关系.在Di-Ab玻璃中的Mg-O键距是0.2±0.004nm.表明本方法可以作为研究含Mg矿物Mg的配位与局部结构新的结构探针.     

Amphibolites with staurolite and other aluminous minerals: calculated mineral equilibria in NCFMASH

Amphibolite facies mafic rocks that consist mainly of hornblende, plagioclase and quartz may also contain combinations of chlorite, garnet, epidote, and, more unusually, staurolite, kyanite, sillimanite, cordierite and orthoamphiboles. Such assemblages can provide tighter constraints on the pressure and temperature evolution of metamorphic terranes than is usually possible from metabasites. Because of the high variance of most of the assemblages, the phase relationships in amphibolites depend on rock composition, in addition to pressure, temperature and fluid composition. The mineral equilibria in the Na₂O–CaO–FeO–MgO–Al₂O₃–SiO₂–H₂O (NCFMASH) model system demonstrate that aluminium content is critical in controlling the occurrence of assemblages involving hornblende with aluminous minerals such as sillimanite, kyanite, staurolite and cordierite. Except in aluminous compositions, these assemblages are restricted to higher pressures. The iron to magnesium ratio (X_Fe), and to a lesser extent, sodium to calcium ratio, have important roles in determining which (if any) of the aluminous minerals occur under particular pressure–temperature conditions. Where aluminous minerals occur in amphibolites, the P–T–X dependence of their phase relationships is remarkably similar to that in metapelitic rocks. The mineral assemblages of Fe‐rich amphibolites are typically dominated by garnet‐ and staurolite‐bearing assemblages, whereas their more Mg‐rich counterparts contain chlorite and cordierite. Assemblages involving staurolite–hornblende can occur over a wide range of pressures (4–10 kbar) at temperatures of 560–650 °C; however, except in the more aluminous, iron‐rich compositions, they occupy a narrow pressure–temperature window. Thus, although their occurrence in ‘typical’ amphibolites may be indicative of relatively high pressure metamorphism, in more aluminous compositions their interpretation is less straightforward.     

珊瑚的影像密度恢复南海海表温度

将南海西沙永兴岛 ( 1 6°50′N,1 1 2°2 0′E)西北的造礁珊瑚的岩芯 ,制成 X射线负片。用显微光密度计在 X射线负片上获得沿生长轴方向的影像密度值 ,时间序列为 1 937～ 1 993年。根据影像密度数据 ,计算出珊瑚的各年生长率和钙化率的代用指标。珊瑚生长率和钙化率的代用指标都与 SST呈显著正相关。根据 1 960～ 1 993年的资料统计 ,相关系数分别是 0 .91和 0 .85,从而建立了珊瑚生长率温度计和钙化率代用指标温度计。并用这两个温度计测算到 1 937年 ,揭示出南海的 SST变化既受到全球气候环境变化为主的影响 ,也受到半封闭海域格局的影响     

Statistical algorithms for identification of astronomical X‐ray sources

Observations of present and future X‐ray telescopes include a large number of ipitous sources of unknown types. They are a rich source of knowledge about X‐ray dominated astronomical objects, their distribution, and their evolution. The large number of these sources does not permit their individual spectroscopical follow‐up and classification. Here we use Chandra Multi‐Wavelength public data to investigate a number of statistical algorithms for classification of X‐ray sources with optical imaging follow‐up. We show that up to statistical uncertainties, each class of X‐ray sources has specific photometric characteristics that can be used for its classification. We assess the relative and absolute performance of classification methods and measured features by comparing the behaviour of physical quantities for statistically classified objects with what is obtained from spectroscopy. We find that among methods we have studied, multi‐dimensional probability distribution is the best for both classifying source type and redshift, but it needs a sufficiently large input (learning) data set. In absence of such data, a mixture of various methods can give a better final result.We discuss some of potential applications of the statistical classification and the enhancement of information obtained in this way. We also assess the effect of classification methods and input data set on the astronomical conclusions such as distribution and properties of X‐ray selected sources. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Supernova remnants,planetary nebulae and superbubbles: Prospects for new XMM‐Newton observations

Important results achieved over the last years on supernova remnants, planetary nebulae and superbubbles are briefly reviewed in the context of X‐ray observations. I intend to review the important open scientific questions in these fields, and the specific contributions that can be made by XMM‐Newton. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Using X‐ray observations to identify the particle acceleration mechanisms in VHE SNRs and “dark” VHE sources

Very high energy (VHE) γ‐ray observations have proven to be very successful in localizing Galactic acceleration sites of VHE particles. Observations of shell‐type supernova remnants have confirmed that particles are accelerated to VHE energies in supernova blast waves; the interpretation of the γ‐ray data in terms of hadronic or leptonic particle components in these objects relies nevertheless strongly on input from X‐ray observations. The largest identified Galactic VHE source class consists of pulsar wind nebulae, as detected in X‐rays. Many of the remaining VHE sources remain however unidentified until now. With X‐ray observations of these enigmatic “dark” objects one hopes to solve the following questions: What is the astrophysical nature of these sources? Are they predominantly electron or hadron accelerators? And what is their contribution to the overall cosmic ray energy budget? The paper aims to provide an overview over the identification status of the Galactic VHE source population. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

>“Resolving” neutron stars physics and geometry

The unprecedented harvest of X‐ray photons detected from dozens of isolated neutron stars has made it possible to glimpse at their emission mechanisms as well as at their emission geometry. Rotating hot spot(s), superimposed to the global thermal emission from the neutron star surface, are seen from several objects, allowing to probe the stars' external heating sources. Non‐thermal emission is also seen to vary as the stars rotate. Moreover, absorption features have been detected in the spectra of several objects, allowing to probe (tentatively) the stars' magnetic fields. Spectacular tails, trailing the stars' supersonic motion, trace the boundaries of the relativist winds streaming from the star's magnetosphere. Apart from classical radio pulsar and certified radio‐quiet neutron stars, XMM‐Newton has devoted significant observation time to the enigmatic central compact objects, presumably isolated neutron stars shining at the center of their supernova remnants. Far from showing a unifying behaviour, XMM‐Newton data have unveiled a surprising diversity. Understanding the reason(s) behind such diversity is the challenge for the next decade of X‐ray observations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X‐ray spectroscopy of early‐type stars: The present and the future

XMM‐Newton and Chandra have boosted our knowledge about the X‐ray emission of early‐type stars (spectral types OB and Wolf‐Rayet). However, there are still a number of open questions that need to be addressed in order to fully understand the X‐ray spectra of these objects. Many of these issues require high‐resolution spectroscopy or monitoring of a sample of massive stars. Given the moderate X‐ray brightness of these targets, rather long exposure times are needed to achieve these goals. In this contribution, we review our current knowledge in this field and present some hot topics that could ideally be addressed with XMM‐Newton over the next decade. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)