Optical and infrared diagnostics of SDSS galaxies in the SWIRE survey

We present the rest-frame optical and infrared colours of a complete sample of  1114 z < 0.3  galaxies from the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Legacy Survey and the Sloan Digital Sky Survey (SDSS). We discuss the optical and infrared colours of our sample and analyse in detail the contribution of dusty star-forming galaxies and active galactic nuclei (AGN) to optically selected red sequence galaxies.
We propose that the optical  ( g − r )  colour and infrared  log( L ₂₄/ L _3.6)  colour of galaxies in our sample are determined primarily by a bulge-to-disc ratio. The  ( g − r )  colour is found to be sensitive to the bulge-to-disc ratio for disc-dominated galaxies, whereas the  log( L ₂₄/ L _3.6)  colour is more sensitive for bulge-dominated systems.
We identify ∼18 per cent (195 sources) of our sample as having red optical colours and infrared excess. Typically, the infrared luminosities of these galaxies are found to be at the high end of star-forming galaxies with blue optical colours. Using emission-line diagnostic diagrams, 78 are found to have an AGN contribution and 117 are identified as star-forming systems. The red  ( g − r )  colour of the star-forming galaxies could be explained by extinction. However, their high optical luminosities cannot. We conclude that they have a significant bulge component.
The number densities of optically red star-forming galaxies are found to correspond to ∼13 per cent of the total number density of our sample. In addition, these systems contribute ∼13 per cent of the total optical luminosity density, and 28 per cent of the total infrared luminosity density of our SWIRE/SDSS sample. These objects may reduce the need for 'dry mergers'.     

Environments of Supernova Remnants Which Contain Different Types of Neutron Star

Understanding the formation and evolution of massive galaxies provides important keys to constrain the baryon assembly processes in the ΛCDM hierarchical scenario. We review the main results obtained so far with the K20 and other recent near-IR surveys on the redshift distribution, the evolution of the luminosity function and luminosity density, the nature of old and dusty EROs, the evolution of the galaxy stellar mass function and the nature of luminous starbursts at z∼2 which may be the progenitors of the present-day massive spheroidal galaxies.     

速度分布和银盘厚度效应对正常脉冲星Z向分布的影响

基于彭秋和等1978年得到的无扰动有限厚盘引力势,根据两个引力势参数(h_(z1)= 0．001kpc,h_(z2)=0．325 kpc)和两个速度分布参数(σ_(v1)=115km/s,σ_(v2)=200 km/s)组合的4种情况,对4×10~5颗脉冲星做了三维蒙特卡洛模拟．4×10~5颗脉冲星按着10~8年间隔被分成20组,计算了每组“逃逸”脉冲星所占比例．对每组中“未逃逸”脉冲星,分别在0＜r＜25kpc和5＜r＜11kpc两个区域中对|z|分布做了统计,研究了“未逃逸”脉冲星在这两个区域中的分段标高和累积标高的演化特征．“未逃逸”脉冲星的分段标高在一定空间范围内的变化不规则,但累积标高的变化却比较平滑．在相对长的时间里(＞10~8年),银盘厚度对脉冲星累积标高演化有显著的复杂影响；在相对短的时间中(＜2×10~7年),这种效应很小,而且累积标高对时间的依赖关系是线性的．在长时间里,初始速度分布对累积标高也有显著影响．在引力势h_(z2)=0．325 kpc的条件下,在径向范围5＜r＜11kpc和时间t=9．22×10~6年以及σ_(v2)=200km/s的情况下,模拟的累积标高是0．596±0．005 kpc．     

Final analysis of ELAIS 15-μm observations: method, reduction and catalogue

We present the final analysis of the European Large Area Infrared Space Observatory ( ISO ) Survey (ELAIS) 15-μm observations, carried out with the ISO Camera (ISOCAM) instrument on board the ISO .
The data-reduction method, known as the Lari Method, is based on a mathematical model of the behaviour of the detector and was specifically designed for the detection of faint sources in ISOCAM/ISO Photopolarimeter (ISOPHOT) data. The method is fully interactive and leads to very reliable and complete source lists.
The resulting catalogue includes 1923 sources detected with signal-to-noise ratio of  > 5  in the 0.5–100 mJy flux range and over an area of 10.85 deg² split into four fields, making it the largest non-serendipitous extragalactic source catalogue obtained to date from the ISO data.
This paper presents the concepts underlying the data-reduction method together with its latest enhancements. The data-reduction process, the production and basic properties of the resulting catalogue are discussed. The catalogue quality is assessed by means of detailed simulations, optical identifications and comparison with previous analyses.     

Testing the modified Press–Schechter model against N-body simulations

A modified version of the extended Press–Schechter model for the growth of dark-matter haloes was introduced in two previous papers, with the aim of explaining the mass–density relation shown by haloes in high-resolution cosmological simulations. In this model, major mergers are well separated from accretion, thereby allowing a natural definition of halo formation and destruction. This makes it possible to derive analytic expressions for halo formation and destruction rates, the mass accretion rate and the probability distribution functions of halo formation times and progenitor masses. The stochastic merger histories of haloes can be readily derived and easily incorporated into semi-analytical models of galaxy formation, thus avoiding the usual problems encountered in the construction of Monte Carlo merger trees from the original extended Press–Schechter formalism. Here we show that the predictions of the modified Press–Schechter model are in good agreement with the results of N -body simulations for several scale-free cosmologies.