Zusammenfassung
Winds are predicted to be ubiquitous in low-mass, actively star-forming
galaxies. Observationally, winds have been detected in relatively few local
dwarf galaxies, with even fewer constraints placed on their timescales. Here,
we compare galactic outflows traced by diffuse, soft X-ray emission from
Chandra Space Telescope archival observations to the star formation histories
derived from Hubble Space Telescope imaging of the resolved stellar populations
in six starburst dwarfs. We constrain the longevity of a wind to be of order 25
Myr based on galaxies whose starburst activity has already declined, although a
larger sample is needed to confirm this result. Compared to estimates from
spiral galaxies, we find a higher average efficiency for converting the
mechanical energy of stellar feedback to thermal, soft X-ray emission. The
outflows have likely been sustained for timescales comparable to the duration
of the starbursts (i.e., 100's Myr), after taking into account the time for the
development and cessation of the wind. The wind timescales imply that material
is driven to larger distances in the circumgalactic medium than previously
thought from assuming 5-10 Myr starburst durations, and that less material is
recycled back to the host galaxy on short timescales. In the detected outflows,
the expelled hot gas shows various morphologies which are not consistent with a
simple biconical outflow structure. The sample and analysis are part of a
larger program, the STARBurst IRregular Dwarf Survey (STARBIRDS), aimed at
understanding the lifecycle and impact of starburst activity in low-mass
systems.
Nutzer