Oxygen yields as a constraint on feedback processes in galaxies
  We study the interplay between several properties determined from Optical and
a combination of Optical/Radio measurements, such as the effective Oxygen yield
(y_eff), the star formation efficiency, gas metallicity, depletion time, gas
fraction, and baryonic mass(M_bar), among others. We use spectroscopic data
from the SDSS survey, and HI information from the ALFALFA survey to build a
statistically significant sample of more than 5,000 galaxies. Furthermore, we
complement our analysis with data from the GASS and COLD GASS surveys, and with
a sample of star-forming galaxies from the Virgo cluster. Additionally, we have
compared our results with predictions from the EAGLE simulations, finding a
very good agreement when using the high-resolution run. We explore in detail
the M_bar-y_eff relation, finding a bimodal trend that can be separated when
the stellar age of galaxies is considered. On one hand, y_eff increases with
M_bar for young galaxies(log(t_r) < 9.2 yr), while y_eff shows an
anti-correlation with M_bar for older galaxies (log(t_r) > 9.4 yr). While a
correlation between M_bar and y_eff has been observed and studied before,
mainly for samples of dwarfs and irregular galaxies, their anti-correlated
counterpart for massive galaxies has not been previously reported. The EAGLE
simulations indicate that AGN feedback must have played an important role in
their history by quenching their star formation rate, whereas low mass galaxies
would have been affected by a combination of outflows and infall of gas.
