# A Possible Time-Delayed Brightening of the Sgr A* Accretion Flow after the Pericenter Passage of G2 Cloud

## TL;DR

This study uses 3D magnetohydrodynamic simulations to predict a delayed radio brightening of Sgr A* following G2 cloud's pericenter passage, due to magnetic field amplification and increased synchrotron emission.

## Contribution

It introduces a novel simulation-based prediction of time-delayed brightening of Sgr A* linked to G2 cloud's pericenter passage, highlighting magnetic field reorganization effects.

## Key findings

- Magnetic energy increases 3-4 times 5-10 years after G2's pericenter.
- Radio and infrared luminosity of Sgr A* is expected to rise around 2020.
- Magnetic field amplification is driven by magneto-rotational instability.

## Abstract

A possibility of time-delayed radio brightenings of Sgr A* triggered by the pericenter passage of the G2 cloud is studied by carrying out global three-dimensional magnetohydrodynamic simulations taking into account the radiative cooling of the tidal debris of the G2 cloud. Magnetic fields in the accretion flow are strongly perturbed and re-organized after the passage of G2. We have found that the magnetic energy in the accretion flow increases by a factor 3-4 in 5-10 years after the pericenter passage of G2 by a dynamo mechanism driven by the magneto-rotational instability. Since this B-field amplification enhances the synchrotron emission from the disk and the outflow, the radio and the infrared luminosity of Sgr A* is expected to increase around A.D. 2020. The time-delay of the radio brightening enables us to determine the rotation axis of the preexisting disk.