We present an X-ray study of the massive edge-on Sa galaxy , Sombrero ( M 104 ; NGC 4594 ) , based on XMM-Newton and Chandra observations .
A list of 62 XMM-Newton and 175 Chandra discrete X-ray sources is provided , the majority of which are associated with the galaxy .
Spectral analysis is carried out for relatively bright individual sources and for an accumulated source spectrum .
At energies \gtrsim 2 keV , the source-subtracted X-ray emission is distributed similarly as the stellar K-band light and is primarily due to the residual emission from discrete sources .
At lower energies , however , a substantial fraction of the source-subtracted emission arises from diffuse hot gas extending to \sim 20 kpc from the galactic center .
The galactic disk shows little X-ray emission and instead shadows part of the X-ray radiation from the bulge .
The observed diffuse X-ray emission from the galaxy shows a steep spectrum that can be characterized by an optically-thin thermal plasma with temperatures of \sim 0.6-0.7 keV , varying little with radius .
The diffuse emission has a total luminosity of \sim 3 \times 10 ^ { 39 } { ~ { } erg~ { } s ^ { -1 } } in the 0.2-2 keV energy range .
This luminosity is significantly smaller than the prediction by current numerical simulations for galaxies as massive as Sombrero .
However , such simulations do not include the effect of quienscent stellar feedback ( e.g. , ejecta from evolving stars and Type Ia supernovae ) against the accretion from intergalactic medium .
We argue that the stellar feedback likely plays an essential role in regulating the physical properties of hot gas .
Indeed , the observed diffuse X-ray luminosity of Sombrero accounts for at most a few percent of the expected mechanical energy input from Type Ia supernovae .
The inferred gas mass and metal content are also substantially less than those expected from stellar ejecta .
We speculate that a galactic bulge wind , powered primarily by Type Ia supernovae , has removed much of the “ missing ” energy and metal-enriched gas from the region revealed by the X-ray observations .