The miniJPAS survey: The role of group environment in quenching the star formation

The miniJPAS survey has observed $\sim 1$ deg${}^2$ on the AEGIS field with 60 bands (spectral resolution of $R\sim 60$) in order to demonstrate the capabilities of the Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) that will map $\sim 8000$ deg${}^2$ of the northern sky in the next years. This paper shows the power of J-PAS to detect low mass groups and characterise their galaxy populations up to $z\sim 1$. We use the spectral energy distribution fitting code BaySeAGal to derive the stellar population properties of the galaxy members in 80 groups at $z\le 0.8$ previously detected by the AMICO code, as well as for a galaxy field sample retrieved from the whole miniJPAS sample. We identify blue, red, quiescent, and transition galaxy populations through their rest-frame (extinction corrected) colour, stellar mass ($M_{\star }$) and specific star formation rate. We measure their abundance as a function of $M_{\star }$ and environment. We find: (i) The fraction of red and quiescent galaxies in groups increases with $M_{\star }$ and it is always higher in groups than in the field. (ii) The quenched fraction excess (QFE) in groups strongly increases with $M_{\star }$, (from a few percent to higher than 60% in the mass range ${10}^{10}-3\times {10}^{11}$ $M_{\odot }$. (iii) The abundance excess of transition galaxies in groups shows a modest dependence with $M_{\star }$ (iv) The fading time scale is very short ($<1.5$ Gyr), indicating that the star formation declines very rapidly in groups. (v) The evolution of the galaxy quenching rate in groups shows a modest but significant evolution since $z\sim 0.8$, compatible with an evolution with constant $QFE=0.4$, previously measured for satellites in the nearby Universe, and consistent with a scenario where the low-mass star-forming galaxies in clusters at $$$$ are environmentally quenched.