We review recent observational results on early type galaxies obtained with high spatial resolution Chandra data. With its unprecedented high spatial resolution, Chandra reveals many intriguing features in early type galaxies which were not identified with the previous X-ray missions. In particular, various fine structures of the hot ISM in early type galaxies are detected, for example, X-ray cavities which are spatially coincident with radio jets/lobes, indicating the interaction between the hot ISM and radio jets. Also point sources (mostly LMXBs) are individually resolved down to Lx = a few x 10 37 erg sec-1 and it is for the first time possible to unequivocally investigate their properties and the X-ray luminosity function. After correcting for incompleteness, the XLF of LMXBs is well reproduced by a single power law with a slope of -1.0 - -1.5, which is in contrast to the previous report on the existence of the XLF break at Lx, Eddington = 2 x 10 38 erg sec-1 (i.e., Eddington luminosity of a neutron star binary). Carefully considering both detected and undetected, hidden populations of point sources we further discuss the XLF of LMXBs and the metal abundance of the hot ISM and their impact on the properties of early type galaxies.

We review recent systematic investigation of the X-ray spectra of early type galaxies by using the Einstein data base and present new results by the ROSAT observations. The Einstein data suggested that the galaxies with low X-ray to optical luminosity ratio may have another very soft component. ROSAT observations confirm its presence and call for further study to understand the nature of this very soft emission. The X-ray bright galaxies have emission temperature of ∼0.8keV ∼0.8keV and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.

We have systematically investigated the X-ray spectra of normal galaxies, by using the Imaging Proportional Counter (IPC) data in the Einstein data base. We employed the X-ray color-color plot as well as the standard model fitting method which requires higher signal to noise ratio. We discuss X-ray emission mechanisms in terms of their spectral properties and the signature of cooling flows which are most likely present in X-ray bright early type galaxies. On the average, fits to absorbed thermal spectra show that the X-ray emission temperature of spirals is higher than that of ellipticals. This is consistent with our understanding that accreting binaries are a major X-ray source in spirals, while extended gaseous halos are present in ellipticals. The emission temperature becomes lower with increasing X-ray to optical luminosity ratio in E and S0 galaxies. This result is what we would expect if the emission of X-ray faint early type galaxies consists of a large evolved stellar component, while the gaseous emission becomes dominant in X-ray brighter galaxies. We also find a cool, self-absorbed core in some early type galaxies, which directly indicates the presence of cooling flows in such galaxies.