Multiple Mechanisms Quench Passive Spiral Galaxies

TL;DR

This study investigates the quenching mechanisms of passive spiral galaxies, finding that both environmental factors like cluster interactions and internal structures contribute, with different processes dominating based on galaxy mass.

Contribution

It provides a comprehensive analysis showing multiple mechanisms, including environmental and internal factors, are responsible for quenching star formation in passive spiral galaxies, highlighting mass-dependent differences.

Findings

Low mass passive spirals are in rich clusters, suggesting environmental quenching.

High mass passive spirals have high bar fractions and are found in groups, indicating internal and environmental influences.

Multiple quenching mechanisms are needed to explain the passive spiral galaxy population.

Abstract

We examine the properties of a sample of 35 nearby passive spiral galaxies in order to determine their dominant quenching mechanism(s). All five low mass ($\textrm{M}_{\star} < 1 \times 10^{10} \textrm{M}_{\odot}$) passive spiral galaxies are located in the rich Virgo cluster. This is in contrast to low mass spiral galaxies with star formation, which inhabit a range of environments. We postulate that cluster-scale gas stripping and heating mechanisms operating only in rich clusters are required to quench low mass passive spirals, and ram-pressure stripping and strangulation are obvious candidates. For higher mass passive spirals, while trends are present, the story is less clear. The passive spiral bar fraction is high: 74$\pm$15%, compared with 36$\pm$5% for a mass, redshift, and T-type matched comparison sample of star forming spiral galaxies. The high mass passive spirals occur mostly, but not exclusively, in groups, and can be central or satellite galaxies. The passive spiral group fraction of 74$\pm$15% is similar to that of the comparison sample of star forming galaxies at 61$\pm$7%. We find evidence for both quenching via internal structure and environment in our passive spiral sample, though some galaxies have evidence of neither. From this, we conclude no one mechanism is responsible for quenching star formation in passive spiral galaxies - rather, a mixture of mechanisms are required to produce the passive spiral distribution we see today.