Cluster environment quenches the star formation of low-mass satellite galaxies from the inside-out

TL;DR

This study shows that low-mass satellite galaxies in clusters tend to quench their star formation from the inside-out, mainly due to environmental effects like tidal and hydrodynamical stripping, especially in dense cluster cores.

Contribution

It provides new evidence that cluster environments induce inside-out quenching in low-mass satellites, using spectral indices and SED fitting from SDSS data.

Findings

Low-mass satellites in clusters quench inside-out more than isolated counterparts.

Inside-out quenching is strongest in galaxy cores and for those below the star formation main sequence.

Environmental effects like gas stripping lead to starvation, suppressing outer star formation.

Abstract

Environment plays a critical role in the star formation history of galaxies. Tidal and hydrodynamical stripping, prominent in cluster environment, can remove the peripheral gas of galaxies and star formation may thus be environmentally suppressed from the outside-in. We revisit the environmental dependence of the radial gradient of specific star formation rate (sSFR) profile. We probe the radial gradient by using the archival spectral indices D4000n and HdA measured from SDSS fiber spectra, to indicate central sSFR, and the total sSFR from fitting the spectral energy distribution. Despite the low spatial resolution, the wealth of SDSS data allows to disentangle the dependences on stellar mass, sSFR, and environment. We find that low-mass satellite galaxies in the mass range 9 < log M/M_solar < 9.8 on average quench in more inside-out pattern compared to isolated galaxies matched in mass, sSFR, and fiber coverage. This environmental effect is particularly strong for galaxies below the star formation main sequence, and peaks for those in the core of massive clusters where the phase-space diagram reveals clear links between the inside-out quenching and orbital properties. Our results suggest that both tidal and hydrodynamical interactions in cluster environment suppress the star formation of satellites mainly from the inside-out. As accreted gas of low angular momentum from hot gas halos is an important source for replenishing central gas reservoir, we discuss how gas stripping in clusters may lead to starvation and cause inside-out quenching when the outer star-forming discs are not significantly affected.