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Extended stellar substructure surrounding the Bo\"otes I dwarf spheroidal galaxy

Research paper by T. A. Roderick, A. D. Mackey, H. Jerjen, G. S. Da Costa

Indexed on: 01 Jul '16Published on: 01 Jul '16Published in: arXiv - Astrophysics - Astrophysics of Galaxies



Abstract

We present deep stellar photometry of the Bo\"otes I dwarf spheroidal galaxy in g and i band filters, taken with the Dark Energy Camera at Cerro Tololo in Chile. Our analysis reveals a large, extended region of stellar substructure surrounding the dwarf, as well as a distinct over-density encroaching on its tidal radius. A radial profile of the Bo\"otes I stellar distribution shows a break radius indicating the presence of extra-tidal stars. These observations strongly suggest that Bo\"otes I is experiencing tidal disruption, although not as extreme as that exhibited by the Hercules dwarf spheroidal. Combined with revised velocity dispersion measurements from the literature, we see evidence suggesting the need to review previous theoretical models of the Bo\"otes I dwarf spheroidal galaxy.