The Intrinsic Star Formation Rate Function In The Illustristng Simulations And Sdss Survey At The Present Universe

We present the first measurements on Eddington-bias-removed star for-mation rate function(SFRF),Cosmic star formation rate density(CSFRD)and specific star formation rate function(sSFRF)from the Sloan Digital Sky Survey Data Release 7.The intrinsic SDSS SFRF of our work relies on star formation rates derived from Spectral Energy Distribution(SED)and is in good agreement with measurements from previous data in the literature that relied on UV SFRs but its high star-forming end is under-predicted with respect IR and radio tracers.We demonstrate that the in-trinsic sSFRF from SDSS has a bi-modal form with the one peak found at sSFR?10-9.7 yr-1 representing the star forming objects while the other peak is found at sSFR?10-12yr-1 representing the quenched population.In addition,we compare our observations with the predictions from the Illus-trisTNG and Illustris simulations and show that the "TNG" model performs much better than its predecessor.However,we show that the simulated SFRF and CSFRD of TNG simulations are highly dependent on resolution,reflect-ing the limitations of the model and today state-of-the-art simulations.We demonstrate that the bi-modal,two peaked sSFRF implied by the SDSS ob-servations does not appear in TNG regardless of the adopted box-size or resolution.This tension reflects the need for an inclusion of an additional efficient quenching mechanism to the TNG model.