Abstract
Do the theorised different formation mechanisms of fast and slow rotators
produce an observable difference in their star formation histories? To study
this we identify quenching slow rotators in the MaNGA sample by selecting those
which lie below the star forming sequence and identify a sample of quenching
fast rotators which were matched in stellar mass. This results in a total
sample of 194 kinematically classified galaxies, which is agnostic to visual
morphology. We use u-r and NUV-u colours from SDSS and GALEX and an existing
inference package, STARPY, to conduct a first look at the onset time and
exponentially declining rate of quenching of these galaxies. An
Anderson-Darling test on the distribution of the inferred quenching rates
across the two kinematic populations reveals they are statistically
distinguishable ($3.2\sigma$). We find that fast rotators quench at a much
wider range of rates than slow rotators, consistent with a wide variety of
physical processes such as secular evolution, minor mergers, gas accretion and
environmentally driven mechanisms. Quenching is more likely to occur at rapid
rates ($1~Gyr$) for slow rotators, in agreement with
theories suggesting slow rotators are formed in dynamically fast processes,
such as major mergers. Interestingly, we also find that a subset of the fast
rotators quench at these same rapid rates as the bulk of the slow rotator
sample. We therefore discuss how the total gas mass of a merger, rather than
the merger mass ratio, may decide a galaxy's ultimate kinematic fate.
Description
[1709.09175] SDSS-IV MaNGA: The Different Quenching Histories of Fast and Slow Rotators
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