Testing the Relationship Between Bursty Star Formation and Size
  Fluctuations of Local Dwarf Galaxies
  Stellar feedback in dwarf galaxies plays a critical role in regulating star
formation via galaxy-scale winds. Recent hydrodynamical zoom simulations of
dwarf galaxies predict that the periodic outward flow of gas can change the
gravitational potential sufficiently to cause radial migration of stars. To
test the effect of bursty star formation on stellar migration, we examine star
formation observables and sizes of 86 local dwarf galaxies. We find a
correlation between the R-band half-light radius (R$_e$) and far-UV luminosity
(L$_{FUV}$) for stellar masses below 10$^8 $ M$_{\odot}$ and a weak correlation
between the R$_e$ and H$\alpha$ luminosity (L$_{H\alpha}$). We produce mock
observations of eight low-mass galaxies from the FIRE-2 cosmological
simulations and measure the similarity of the time sequences of R$_e$ and a
number of star formation indicators with different timescales. Major episodes
of R$_e$ time sequence align very well with the major episodes of star
formation, with a delay of $\sim$ 50 Myrs. This correlation decreases towards
SFR indicators of shorter timescales such that $R_e$ is weakly correlated with
L$_{FUV}$ (10-100 Myr timescale) and is completely uncorrelated with
L$_{H\alpha}$ (a few Myr timescale), in agreement with the observations. Our
findings based on FIRE-2 suggest that the R-band size of a galaxy reacts to
star formation variations on a $\sim50$ Myr timescale. With the advent of a new
generation of large space telescopes (e.g., JWST), this effect can be examined
explicitly in galaxies at higher redshifts where bursty star formation is more
prominent.
