ELVES III: Environmental Quenching by Milky Way-Mass Hosts

TL;DR

This study investigates the environmental factors affecting star formation cessation in dwarf satellite galaxies around Milky Way-like hosts, revealing gradual quenching times and dependencies on satellite and host properties.

Contribution

It provides new observational data on quenched fractions and quenching times across various satellite masses and host environments, comparing these with semi-analytic models and simulations.

Findings

Quenched fractions drop below 50% at satellite M* ~ 10^8 M_sun.

Quenching times increase gradually with satellite stellar mass.

Results align with models of ram-pressure stripping influenced by environment and orbit.

Abstract

Isolated dwarf galaxies usually exhibit robust star formation but satellite dwarf galaxies are often devoid of young stars, even in Milky Way-mass groups. Dwarf galaxies thus offer an important laboratory of the environmental processes that cease star formation. We explore the balance of quiescent and star-forming galaxies (quenched fractions) for a sample of ~400 satellite galaxies around 30 Local Volume hosts from the Exploration of Local VolumE Satellites (ELVES) Survey. We present quenched fractions as a function of satellite stellar mass, projected radius, and host halo mass, to conclude that overall, the quenched fractions are similar to the Milky Way, dropping below 50% at satellite M* ~ 10^8 M_sun. We may see hints that quenching is less efficient at larger radius. Through comparison with the semi-analytic modeling code satgen, we are also able to infer average quenching times as a function of satellite mass in host halo-mass bins. There is a gradual increase in quenching time with satellite stellar mass rather than the abrupt change from rapid to slow quenching that has been inferred for the Milky Way. We also generally infer longer average quenching times than recent hydrodynamical simulations. Our results are consistent with models that suggest a wide range of quenching times are possible via ram-pressure stripping, depending on the clumpiness of the circumgalactic medium, the orbits of the satellites, and the degree of earlier preprocessing.