Colliding with G2 near the Galactic Centre: a geometrical approach

Abstract

Abstract The object G2 will pass within ∼100 au from Sgr A* in 2014. Due to its very short periapse, the study of the dynamical evolution of this object in the short-term future may offer some insight into the region surrounding the supermassive black hole at the centre of the Galaxy. With this scenario in mind, it has recently been proposed by Bartos et al. that, prior to its perinigricon, G2 will likely experience multiple encounters with members of the black hole and neutron-star populations believed to orbit near the Galactic Centre. Here, we further explore this possibility and study the general case for collisions with the G2 object using the latest orbital solutions provided by Phifer et al. and Gillessen et al., and a Monte Carlo approach to estimate the minimum orbit intersection distance (MOID) with G2 as a function of the orbital parameters of the incoming body. Our results indicate that encounters at distances closer than 100 au started to become statistically significant only during the last few years or so. MOIDs under 100 au are statistically more probable for the most dynamically cold orbits. If there is a population of objects moving in low-inclination, low-eccentricity orbits around the central black hole, the highest probability for a close encounter with G2 is found to be in the period 2014 January–March, but enhanced activity due to encounters may start as early as 2013 July–August.