Speaker
Kathryn Kreckel
(MPIA)
Description
While spiral arms are the most prominent sites for star formation in disk galaxies,
interarm star formation contributes significantly to the overall star formation
budget. However, it is still an open question if the star formation proceeds
differently in the arm and inter-arm environment. We use deep VLT/MUSE optical IFU
spectroscopy to resolve and fully characterize the physical properties of 428
interarm and arm HII regions in the nearby grand design spiral galaxy NGC 628.
Unlike molecular clouds (the fuel for star formation) which exhibit a clear
dependence on galactic environment, we find that most HII region properties
(luminosity, size, metallicity, ionization parameter) are independent of environment.
One clear exception is the diffuse ionized gas (DIG) contribution to the arm and
interarm flux (traced via the temperature sensitive [SII]/Halpha line ratio inside
and outside of the HII region boundaries). We find a systematically higher DIG
background within HII regions, particularly on the spiral arms. Correcting for this
DIG contamination can result in significant (70%) changes to the star formation rate
measured. We also show preliminary results comparing well-corrected star formation
rates from our MUSE HII regions to ALMA CO(2-1) molecular gas observations at matched
1"=35pc resolution, tracing the Kennicutt-Schmidt star formation law at the scales
relevant to the physics of star formation. We estimate the timescales relevant for
GMC evolution using distance from the spiral arm as a proxy for age, and test whether
star formation feedback or galactic-scale dynamical processes dominate GMC disruption.
Primary author
Kathryn Kreckel
(MPIA)
