G2 Cloud


G2 is a cloud on a near-radial orbit about our galaxy's central black hole, Sagittarius A*. TA scientists are working on a number of observational and theoretical projects relating to this fascinating object.

Postdoctoral researcher James Guillochon is investigating whether the disruption of a nearby giant star by Sagittarius A* may be capable of producing clouds similar to G2 in the galactic center. On the right is a snapshot from a three-dimensional simulation James ran, where material removed from a giant star falls onto a black hole. This material is collimated into a thin stream, and radiatively cools in regions of enhanced density. This cooling leads to clumpiness within the returning stream: it is proposed that one of these clumps is the observed G2 cloud.

Other TA researchers, in a project lead by postdoc Olek Sadowski, have performed general-relativistic magnetohydrodynamic simulations of the cloud's interaction with the accreting gas already present around the Sagittarius black hole.


Dr James Guillochon
Aleksander Sadowski1
Ramesh Narayan1
Lorenzo Sironi
Feryal Özel