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arXiv · 2012.05700

Destruction of the central black hole gas reservoir through head-on galaxy collisions

Yohei Miki·Masao Mori·Toshihiro Kawaguchi
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Abstract

A massive black hole exists in almost every galaxy. They occasionally radiate a vast amount of light by releasing gravitational energy of accreting gas, with a cumulative active period of only a few $10^8$ years, so-called the duty cycle of the Active Galactic Nuclei. Namely, many galaxies today host a starving massive black hole. Although galaxy collisions have been thought to enhance nucleus activity, the origin of the duty cycle, especially the shutdown process, is a still critical issue. Here we show that galaxy collisions are also capable of suppressing black hole fueling by using an analytic model and three-dimensional hydrodynamic simulations, applying the well-determined parameter sets for the galactic collision in the Andromeda galaxy. Our models demonstrate that a central collision of galaxies can strip the torus-shaped gas surrounding the massive black hole, the putative fueling source. The derived condition for switching-off the black hole fueling indicates that a significant fraction of currently bright nuclei can become inactive, reminiscent of fading/dying active nucleus phenomena associated with galaxy merging events. Galaxy collisions may therefore be responsible both for switching-off and turning-on the nucleus activity, depending on the collision orbit (head-on or far-off-centre).

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Yohei Miki, Masao Mori, Toshihiro Kawaguchi. 2020-12-10. Destruction of the central black hole gas reservoir through head-on galaxy collisions. https://doi.org/10.1038/s41550-020-01286-9

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