High Resolution X-ray Spectroscopy of the Local Hot Gas along the 3C 273
  Sightline
  X-ray observations of highly ionized metal absorption lines at z=0 provide
critical information of the hot gas distribution in and around the Milky Way.
We present a study of more than ten-year Chandra and XMM-Newton observations of
3C 273, one of the brightest extragalactic X-ray sources. Compared with
previous work, We obtain much tighter constraints of the physical properties of
the X-ray absorber. We also find a large, non-thermal velocity at ~ 100 - 150
km/s is the main reason for the higher line equivalent width when compared with
other sightlines. Using joint analysis with X-ray emission and ultraviolet
observations, we derive a size of 5 - 15 kpc and a temperature of (1.5-1.8)
10^6 K for the X-ray absorber. The 3C 273 sightline passes through a number of
Galactic structures, including the radio Loop I, IV, the North Polar Spur, and
the neighborhood of the newly discovered "Fermi bubbles". We argue that the
X-ray absorber is unlikely associated with the nearby radio Loop I and IV;
however, the non-thermal velocity can be naturally explained as the result of
the expansion of the "Fermi bubbles". Our data implies an shock-expansion
velocity of 200 - 300 km/s. Our study indicates a likely complex environment
for the production of the Galactic X-ray absorbers along different sightlines,
and highlights the significance of probing galactic feedback with high
resolution X-ray spectroscopy.
