Does the Milky Way produce a starburst wind?

Abstract

We present new FUSE and HST/STIS observations of two high Galactic latitude AGN that we use to measure the nuclear wind velocity of the Milky Way for the first time. We find high velocity C III & O VI at a heliocentric velocity of $+163 \pm 8 {\rm km s^{-1}}$ and C III & N V at $-105 \pm 14 {\rm km s^{-1}}$ toward PKS 2005–489 ($l=350^{\circ}, b=-33^{\circ}$) and C III, C IV, & Si IV and C III & O VI toward Mrk 1383 ($l=349^{\circ}, b=55^{\circ}$) at $+48 \pm 4 {\rm km s^{-1}}$ and $+94 \pm 7 {\rm km s^{-1}}$, respectively. We have estimated the Galactocentric escape velocity of gas above the Galactic Centre along the PKS 2005–489 and Mrk 1383 sight-lines to be $\geq\,$$215 \pm 35$ and $\geq\,$$145 \pm 25 {\rm km s^{-1}}$, respectively. Thus, we have detected both infalling and bound outflowing gas from the Galactic Centre, indicating that the Milky Way does not produce a starburst wind, but a bound Galactic “fountain” instead.