In an effort to understand the correlation between X-ray emission and present star formation rate (SFR), we obtained XMM-Newton data to estimate the X-ray luminosities of a sample of actively starforming HII galaxies. The obtained X-ray luminosities are compared to other well known tracers of star formation activity such as the far infrared and the ultraviolet luminosities. We also compare the obtained results with empirical laws from the literature and with recently published analysis applying synthesis models. We use the time delay between the formation of the stellar cluster and that of the first X-ray binaries, in order to put limits on the age of a given stellar burst. We conclude that the generation of soft X-rays, as well as the Ha or infrared luminosities is instantaneous. The relation between the observed radio and hard X-ray luminosities, on the other hand, points to the existence of a time delay between the formation of the stellar cluster and the explosion of the first massive stars and the consequent formation of supernova remnants and high mass X-ray binaries (HMXB) which originate the radio and hard X-ray fluxes respectively. When comparing hard X-rays with a star formation indicator that traces the first million years of evolution (e.g. Ha luminosities) we found a deficit in the expected X-ray luminosity. This deficit is not found when the X-ray luminosities are compared with infrared luminosities, a star formation tracer that represents an average over the last 10^8 years. The results support the hypothesis that hard X-rays are originated in X-ray binaries which, as supernova remnants, have a formation time delay of a few mega years after the starforming burst.
The Luminosity Functions and Timescales of MYSOs and Compact HII regions
我们提出了一个确定的光度函数的大规模的年轻恒星对象（MYSO）和紧凑的（C）HII地区的银河系内使用的大型，精心挑选的样本，这些来源确定的红色MSX源（RMS）的调查。MYSO光度函数单调减小，使得在$L\gtrsim 10^{5}$ Lsol的情况下几乎没有，当CHII区域被检测到高达~10个$^{6}Lsol. The lifetimes of these phases are also calculated as a function of luminosity by comparison with the luminosity function for local main-sequence OB stars. These indicate that the MYSO phase has a duration ranging from 4x10$ ^{5} $ yrs for 10$ ^{4} $Lsol to ~7x10$ ^{4} $ yrs at 10$ ^{5} $Lsol, whilst the CHII region phase lasts of order 3x10$ ^{5} $ yrs or ~3-10% of the exciting star's main-sequence lifetime. MYSOs between 10$ ^{4} Lsol和~…
Redshift Evolution of the HII Galaxy $L$-$σ$ Relation: Gaussian Process Analysis and Cosmological Implications
Institute of Theoretical Physics, School of Physics, Dalian University of Technology（大连理工大学物理学院理论物理研究所）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；College of Astronomy and Space Sciences, University of Chinese Academy of Sciences（中国科学院大学天文学与空间科学学院）
