Powerful Ejection of Matter from Tidally Disrupted Stars near Massive Black Holes and a Possible Application to Sagittarius A East

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Abstract
When a star is tidally disrupted by a massive black hole, approximately half of its mass is ejected within a solid angle Ω 16(R*/Rp)1/2(M*/Mh)1/2 radians2, where R*, Rp, M*, and Mh are the stellar radius, pericentric distance of the orbit, stellar mass and the black hole mass, respectively. The energy of the ejecta is E ≈ 3.8 × 1054(M*/M☉)2(R☉/R*)(Mh/106M☉)(R*/Rp)2 ergs. The impact of the disrupted matter efflux on the surrounding gas may be like that of a supernova, although with considerably greater energy and with an anisotropy in the ensuing shell structure compared to that of a "standard" supernova event. For the conditions in the Galactic center, these events should occur roughly once every 104-105 yr. Sgr A East, one of the components in the Sgr A complex enshrouding the Galactic nucleus, may be the remnant of a solar mass star disrupted by a 106 M☉ black hole at a pericentric distance Rp ≈ 10 R☉, which results in an explosion with energy ≈ 4 × 1052 ergs.