What has quenched the massive spiral galaxies?

TL;DR

This study identifies rare, very massive quenched spiral galaxies with low molecular gas content, suggesting black hole feedback as a key quenching mechanism, challenging traditional co-evolution models.

Contribution

It reports the discovery of a rare population of massive quenched spiral galaxies and links their quenching to black hole feedback, supported by observations and simulations.

Findings

These galaxies have stellar masses >10^{11} M_ and halo masses >10^{13} M_.

They contain only small amounts of molecular gas.

Black hole feedback likely quenched these spiral galaxies.

Abstract

Quenched massive spiral galaxies have attracted great attention recently, as more data is available to constrain their environment and cold gas content. However, the quenching mechanism is still uncertain, as it depends on the mass range and baryon budget of the galaxy. In this letter, we report the identification of a rare population of very massive, quenched spiral galaxies with stellar mass $\gtrsim10^{11}{\rm~M_\odot}$ and halo mass $\gtrsim10^{13}{\rm~M_\odot}$ from the Sloan Digital Sky Survey at redshift $z\sim0.1$. Our CO observations using the IRAM-30m telescope show that these galaxies contain only a small amount of molecular gas. Similar galaxies are also seen in the state-of-the-art semi-analytical models and hydro-dynamical simulations. It is found from these theoretical models that these quenched spiral galaxies harbor massive black holes, suggesting that feedback from the central black holes has quenched these spiral galaxies. This quenching mechanism seems to challenge the popular scenario of the co-evolution between massive black holes and massive bulges.