What is most likely to cause Sagittarius A* to increase its luminosity suddenly?

Question

Quizplus · Accepted Answer

The infall of a nearby gas cloud is the most likely cause of a sudden increase in luminosity of Sagittarius A*. As the gas cloud falls towards the black hole, it will heat up and emit radiation, which can increase the overall luminosity of the black hole. This has been observed in other galaxies where gas clouds have been seen falling towards the central black hole, causing a sudden increase in luminosity. Spin changes, formation of new spiral arms, and gravitational interactions with globular clusters are all unlikely to cause sudden increases in luminosity.

What Is Most Likely to Cause Sagittarius A* to Increase