On the dominant role of wind in the quasar feedback mode in the late stage evolution of massive elliptical galaxies

TL;DR

This study uses high-resolution hydrodynamical simulations to demonstrate that cold-mode winds from AGN are the primary mechanism heating the gas and suppressing star formation in late-stage massive elliptical galaxies, surpassing hot-mode winds.

Contribution

It reveals that cold-mode AGN winds dominate feedback effects in late-stage galaxy evolution, highlighting their importance over hot-mode winds in heating the interstellar medium.

Findings

Cold-mode winds have larger impact areas than hot-mode winds.

Cumulative energy output is dominated by cold-mode outbursts.

Cold-mode winds can sweep up stellar mass loss material.

Abstract

In this paper we investigate the role of AGN feedback on the late stage evolution of elliptical galaxies by performing high-resolution hydrodynamical simulation in the {\it MACER} framework. By comparing models that take into account different feedback mechanisms, namely AGN and stellar feedback, we find that AGN feedback is crucial in keeping the black hole in a low accretion state and suppressing the star formation. We then compare the energy from AGN radiation and wind deposited in the galaxy and find that only wind can compensate for the radiative cooling of the gas in the galaxy. Further, we investigate which plays the dominant role, the wind from the cold (quasar) or hot (radio) feedback modes, by examining the cumulative energy output and impact area to which the wind can heat the interstellar medium and suppress star formation. Our results indicate that first, although AGN spends most of its time in hot (radio) mode, the cumulative energy output is dominated by the outburst of the cold mode. Second, only the impact area of the cold-mode wind is large enough to heat the gas in the halo, while the hot-mode wind is not. Additionally, the cold-mode wind is capable of sweeping up the material from stellar mass loss. These results indicate the dominant role of cold-mode wind. The limitations of our model, including the absence of jet feedback, are discussed.