Speaker
Nimisha Kumari
(Institute of Astronomy, Cambridge, United Kingdom)
Description
The Kennicutt-Schmidt law relating the surface densities of the star-formation rate
(SFR) and gas (atomic and molecular) is a widely-accepted star-formation law.
However, it is a disk-averaged law smoothing over local variations, and hence may not
provide an explanation for the local relationship between SFR and gas density at the
sub-galactic scale. To further probe this, various groups have carried out
spatially-resolved studies of star-formation in nearby spiral galaxies using
different methods. However, most of these studies do not take into account the effect
of the spatially varying diffuse background which is potentially present in all
star-forming galaxies and affects all the usual SFR tracers (optical, far-ultraviolet
and mid-infrared). In this contribution, we present the results from an analysis of
nearby spiral galaxies using aperture photometry where the effect of the diffuse
background is taken into account. Making use of a novel split of the overall light
distribution as a function of spatial scale allows us to subtract the diffuse
background in the SFR tracers and determine the current localised SFR density. This
is then combined with the gas density estimates (molecular gas from CO(2-1) and
atomic gas from HI) to study the relation between SFR and gas density. Our work
indicates that accounting for a diffuse background leads to a super-linear slope of
the Kennicutt-Schmidt molecular star-formation law.
Primary author
Nimisha Kumari
(Institute of Astronomy, Cambridge, United Kingdom)
