Low- and High-velocity ion{O}{6} in Milky Way-like Galaxies: the Role of Stellar Feedback

Kavli Affiliate: Mark Vogelsberger

| First 5 Authors: Zhijie Zhang, Xiaoxia Zhang, Hui Li, Taotao Fang, Qingzheng Yu

| Summary:

Milky Way-type galaxies are surrounded by a warm-hot gaseous halo containing
a considerable amount of baryons and metals. The kinematics and spatial
distribution of highly-ionized ion species such as ion{O}{6} can be
significantly affected by supernova (SN) explosions and early (pre-SN) stellar
feedback (e.g., stellar winds, radiation pressure). Here, we investigate
effects of stellar feedback on ion{O}{6} absorptions in Milky Way-like
galaxies by analyzing the suites of high-resolution hydrodynamical simulations
under the framework of {it SMUGGLE}, a physically motivated subgrid
interstellar medium and stellar feedback model for the moving-mesh code {sc
Arepo}. We find that the fiducial run with the full suite of stellar feedback
and moderate star formation activities can reasonably reproduce Galactic
ion{O}{6} absorptions observed by space telescopes such as {it FUSE},
including the scale height of low-velocity ($|v_{rm LSR}|< 100, rm
km~s^{-1}$) ion{O}{6}, the column density $-$ line width relation for
high-velocity ($100 leq |v_{rm LSR}|< 400, rm km~s^{-1}$) ion{O}{6}, and
the cumulative ion{O}{6} column densities. In contrast, model variations with
more intense star formation activities deviate from observations further.
Additionally, we find that the run considering only SN feedback is in broad
agreement with the observations, whereas in runs without SN feedback this
agreement is absent, which indicates a dominant role of SN feedback in heating
and accelerating interstellar ion{O}{6}. This is consistent with the current
picture that interstellar ion{O}{6} is predominantly produced by collisional
ionization where mechanical feedback can play a central role. In contrast,
photoionization is negligible for ion{O}{6} production due to the lack of
high-energy ($gtrsim114 {rm eV}$) photons required.

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