The specific star formation rate function at different mass scales and
  quenching: A comparison between cosmological models and SDSS
  We present the eddington bias corrected Specific Star Formation Rate Function
(sSFRF) at different stellar mass scales from a sub-sample of the Sloan Digital
Sky Survey Data Release DR7 (SDSS), which is considered complete both in terms
of stellar mass (${\rm M_{\star}}$) and star formation rate (SFR). The above
enable us to study qualitatively and quantitatively quenching, the distribution
of passive/star-forming galaxies and perform comparisons with the predictions
from state-of-the-art cosmological models, within the same ${\rm M_{\star}}$
and SFR limits. We find that at the low mass end (${\rm M_{\star}} = 10^{9.5} -
10^{10} \, {\rm M_{\odot}}$) the sSFRF is mostly dominated by star-forming
objects. However, moving to the two more massive bins (${\rm M_{\star}} =
10^{10} - 10^{10.5} \, {\rm M_{\odot}}$ and ${\rm M_{\star}} = 10^{10.5} -
10^{11} \, {\rm M_{\odot}}$) a bi-modality with two peaks emerges. One peak
represents the star-forming population, while the other describes a rising
passive population. The bi-modal form of the sSFRFs is not reproduced by a
range of cosmological simulations (e.g. Illustris, EAGLE, Mufasa, IllustrisTNG)
which instead generate mostly the star-forming population, while a bi-modality
emerges in others (e.g. L-Galaxies, Shark, Simba). Our findings reflect the
need for the employed quenching schemes in state-of-the-art models to be
reconsidered, involving prescriptions that allow "quenched galaxies" to retain
a small level of SF activity (sSFR $=$ ${\rm 10^{-11} {\rm yr^{-1}}}$-${\rm
10^{-12} {\rm yr^{-1}}}$) and generate an adequate passive
population/bi-modality even at intermediate masses (${\rm M_{\star}} = 10^{10}
- 10^{10.5} \, {\rm M_{\odot}}$).
