ENVIRONMENTAL EFFECTS ON THE GROWTH OF SUPERMASSIVE BLACK HOLES AND ACTIVE GALACTIC NUCLEUS FEEDBACK.

We investigate how environmental effects by gas stripping alter the growth ofa supermassive black hole (SMBH) and its host galaxy evolution, by means of one-dimensional hydrodynamical simulations that include both mechanical and radiative active galactic nucleus (AGN) feedback effects. By changing the truncation radius of the gas distribution (R_t), beyond which gas stripping is assumed to be effective, we simulate possible environments for satellite and central galaxies in galaxy clusters and groups. The continuous escape of gas outside the truncation radius strongly suppresses star formation, while the growth of the SMBH is less affected by gas stripping because the SMBH accretion is primarily ruled by the density of the central region. As we allow for increasing environmental effects—the truncation radius decreasing from about 410 to 50 kpc— we find that the final SMBH mass declines from about 10⁹ to 8 x 10⁸ Mʘ, but the outflowing mass is roughly constant at about 2 x 10¹⁰ Mʘ. There are larger changes in the mass of stars formed, which declines from about 2 x 10¹⁰ to 2 x 10⁹ Mʘ, and the final thermal X-ray gas, which declines from about 10⁹ to 5 x 10⁸ M&#x 0298;, with increasing environmental stripping. Most dramatic is the decline in the total time that the objects would be seen as quasars, which declines from 52 Myr (for R_t = 377 kpc) to 7.9 Myr (for R_t = 51 kpc). The typical case might be interpreted as a red and dead galaxy having episodic cooling flows followed by AGN feedback effects resulting in temporary transitions of the overall galaxy color from red to green or to blue, with (cluster) central galaxies spending a much larger fraction of their time in the elevated state than do satellite galaxies. Our results imply that various scaling relations for elliptical galaxies, in particular, the mass ratio between the SMBH and its host galaxy, can have dispersions due to environmental effects such as gas stripping. In addition, the simulations also suggest that the increase in AGN fraction in high-redshift galaxy clusters might be related to environmental effects which shut down the SMBH mass accretion in satellite galaxies and reduce their AGN activity. [ABSTRACT FROM AUTHOR]