Ultra-luminous sources in nearby galaxies

This paper presents an update of what we have learned in the last year about the ULX phenomenon. New results are presented on radio emission from Holmberg II and a review is given on the recent X-ray data on timing and spectra. The new X-ray spectroscopic and optical imaging survey of nearby ULX with XMM allows us, for the first time, to place the average properties of these objects on a statistical basis. Direct examination of the sites of ULXs in nearby galaxies shows that 1/3 of them are not in or near star forming regions, indicating that a substantial fraction of ULX are not directly associated with young star formation. There are two ULX which have been identified with B stars as the optical counterparts on the basis of optical spectroscopy. Radio imaging of the Holmberg II ULX shows that it lies in a luminous extended radio source and that the radio emission is not beamed. A statistical study of ULX spectra in nearby galaxies shows that the ratio of ‘high state’ to ‘low state’ ULXs is 1:1 and that the high state objects, in general, are best fit with low temperature black bodies with a steep power law index. The objects with high state spectra are systematically more luminous than the objects with low state spectra consistent with the hypothesis that both are drawn from a population which shows state changes similar to those of black holes in the Milky Way. If this is true then the masses implied for the objects with the low state spectra are greater than 50M.     

The X-ray evolution of galaxies: implications for future X-ray observatories

The X-ray evolution of the luminosity of normal galaxies is primarily driven by the evolution of their X-ray binary populations. The imprints left by a cosmological evolution of the star formation rate (SFR) will cause the average X-ray luminosity of galaxies to appear higher in the redshift range 1–3. As reported by White and Ghosh [ApJ, 504 (1998) L31] the profile of X-ray luminosity with redshift can both serve as a diagnostic probe of the SFR profile and constrain evolutionary models for X-ray binaries. In order to observe the high redshift (z>3) universe in the X-ray band, it is necessary to avoid confusion from foreground field galaxies. We report on the predictions of these models of the X-ray flux expected from galaxies and the implications for the telescope parameters of future deep universe X-ray observatories.     

MIRAX: a Brazilian X-ray astronomy satellite mission

We describe the “Monitor e Imageador de Raios-X” (MIRAX), an X-ray astronomy satellite mission proposed by the high-energy astrophysics group at the National Institute for Space Research (INPE) in Brazil to the Brazilian Space Agency. MIRAX is an international collaboration that includes, besides INPE, the University of California San Diego, the University of Tübingen in Germany, the Massachusetts Institute of Technology and the Space Research Organization Netherlands. The payload of MIRAX will consist of two identical hard X-ray cameras (10–200 keV) and one soft X-ray camera (2–28 keV), both with angular resolution of 5–7^′. The basic objective of MIRAX is to carry out continuous broadband imaging spectroscopy observations of a large source sample (9 months/yr) in the central Galactic plane region. This will allow the detection, localization, possible identification, and spectral/temporal study of the entire history of transient phenomena to be carried out in one single mission. MIRAX will have sensitivities of 5 mCrab/day in the 2–10 keV band (2 times better than the All Sky Monitor on Rossi X-ray Timing Explorer) and 2.6 mCrab/day in the 10–100 keV band (40 times better than the Earth Occultation technique of the Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory). The MIRAX spacecraft will weigh about 200 kg and is expected to be launched in a low-altitude (600 km) circular equatorial orbit around 2007/2008.     

焊接接头典型缺陷的数字X射线尺寸测量技术

为了准确测量焊接接头典型缺陷的尺寸,提出了一种基于半波高法(HWH)的焊接接头缺陷数字射线尺寸测量技术。首先,分析了数字射线检测系统的调制传递函数(MTF),确定了检测系统的空间分辨率。其次,对焊接接头的典型缺陷进行模拟,通过半波高法测量其尺寸。结果表明:依据瑞利判据,运用双丝像质计测定该检测系统的空间分辨率为4.5 Lp/mm;运用该方法测量焊接接头缺陷尺寸,与实际尺寸基本相符,误差小于6.3%,该方法避免了人为因素的影响,精度可满足日常产品的检测需求。     

X射线衍射全谱拟合法测定碳/碳复合材料的点阵常数

利用X射线衍射仪,采用全谱拟含的方法,测定三种不同碳材料的点阵常数、石墨化度及微晶参数,测得三种碳材料(每个样品重复5次试验)六方晶系的a的标准偏差小于2.0×10~(-3),c的标准偏差小于1.4×10~(-3),石墨化度(g)的标准偏差小于1.5,微晶参数(L_(c002))的标准偏差小于0.5,是一种有效的测试碳材料晶体参数的方法.     

天基X射线掠入射式成像望远镜发展现状

阐述了太阳X射线成像观测在空间天气预报中的地位和作用，叙述了掠入射式X射线聚焦成像的基本原理，简要介绍了在轨成功运行的天体X射线成像望远镜和太阳X射线成像望远镜的基本设计和技术指标，并介绍了国内正开发研制的专门服务于空间天气预报的太阳X射线成像望远镜基本设计和主要特点．     

X-ray broad line emission in Seyfert galaxies: Mrk 766 and NGC 4051

Long (>100 ks) observations of the bright Seyfert galaxies Mrk 766 and NGC 4051 have been obtained using XMM-Newton. The RGS 5–38 Å spectra reveal evidence of broad features. These can be modelled with relativistic emission lines coming from the immediate vicinity of a massive rotating black hole. Lines of OVIII, NVII and CVI are required to reproduce the spectrum of Mrk 766, whereas the spectrum of NGC 4051 can be modelled using a single, even broader OVIII line. Both Seyferts also exhibit broad iron line emission in the 2–8 keV range, and the data available thus far suggest that the strength of the low-energy emission lines and the strength of the iron line may be correlated.     

Differential emission measure distributions in X-ray solar flares

X-ray spectrometer RESIK has observed spectra in the four wavelength bands from 3.3 Å to 6.1 Å. This spectral range contains many emission lines of H- and He-like ions for Si, S, Ar and K. These lines are formed in plasma of coronal temperatures (T > 3 MK). Analysis of their intensities allows studying differential emission measure distributions (DEM) in temperature range roughly between 3 MK and 30 MK. The aim of present study was to check whether any relationship exists between the character of DEM distribution, the event phase and the X-ray flare class. To do this we have calculated and analyzed the DEM distributions for a set of flares belonging to different GOES classes from the range B5.6–X1. The DEM distributions have been calculated using “Withbroe–Sylwester” multiplicative, maximum likelihood iterative algorithm. As the input data we have used absolute fluxes observed by RESIK in several spectral bands (lines + continuum). Respective emission functions have been calculated using the CHIANTI v. 5.2 atomic data package.     

CLF-1钢X数字射线照相等效系数的确定

针对聚变堆结构材料拟采用的新材料CLF-1(low-activated ferritic/martensitic steel)钢在进行射线检测过程中没有特定标准参考的问题,采用等效法在相同透照条件开展了不同厚度CLF-1钢和Q235钢的X数字射线等效透照实验研究。基于相同成像条件下两种材料对应的X射线图像具有相同灰度即透照系数相同,通过对比拥有相同图像灰度值的两种材料的厚度,得出CLF-1钢对应于Q235钢的等效透照系数。试验设计了4~20 mm,递增0.5 mm的阶梯厚度的CLF-1钢和Q235钢在100~400 kV(递增50 kV)管电压条件下进行了透照实验,获得了对应电压下CLF-1钢相对于Q235钢的X射线透照等效系数为1.10~1.13。该研究结果对CLF-1钢在进行X射线检测时的检测技术参数的确定具有指导意义。     

2219合金TIG补焊接头亮线影像成因及其力学性能

针对2219合金TIG补焊接头X射线底片亮线影像,开展2219合金不同坡口面角TIG补焊接头组织及性能研究。通过X射线、扫描电镜及能谱仪分析接头底片亮线影像位置对应的微观形貌及成分,并通过拉伸试验评价补焊接头力学性能。结果显示:在0～20°随坡口面角α值的增大,X射线底片上亮线影像的黑度逐渐降低;Cu含量较高的α(Al)+θ非平衡共晶组织对X射线的散射与吸收作用较强,是X射线底片亮线影像的成因;坡口面角α角侧受电磁搅拌作用弱于β角侧,其固-液界面前沿的边界层宽度大于β角侧,且温度梯度及边界层内的成分过冷度均大于β角侧,促进了α角侧枝晶的生长。当β角为20°时,在0°～20°随着α角度值增大,接头的抗拉强度与延伸率逐渐增大,20°时获得了优良的室温力学性能。X射线底片上存在亮线影像的补焊接头力学性能满足型号使用要求,亮线影像结构可不按焊接缺陷处理。