The spectral energy distributions of K+A galaxies from the UV to the
  mid-IR: stellar populations, star formation and hot dust
  We present spectrum synthesis fits to 808 K+A galaxies selected from the
Sloan Digital Sky Survey (SDSS) and population synthesis of their spectral
energy distributions, extending from the far UV (0.15 micron) to the mid IR (22
micron), based on the results of STARLIGHT code fitting to the SDSS spectra.
Our modelling shows that K+A galaxies have undergone a large starburst,
involving a median 50% of their present stellar masses, superposed over an
older stellar population. The metal abundance of the intermediate-age stars
shows that star formation did not take place in pristine gas, but was part of a
dramatic increase in the star formation rates for originally gas-rich objects.
We find no evidence for on-going QSO activity in the UV, which is well modeled
by the emission of intermediate-age stars. We use K+A galaxies as local
counterparts of high redshift objects to test for the presence of Thermally
Pulsing AGB stars in similarly-aged populations and find no excess in the
infrared due to emission from such stars, arguing that more distant galaxies
are indeed old and massive at their redshift. All of our galaxies show
significant excesses in the mid-IR compared to the light from their stars. We
fit this ad hoc with a 300K blackbody. Possible sources include TP-AGB stars,
obscured young star clusters and hidden AGNs, heating a significant dust
component.
