An alternative scenario for the origin of the dwarf spheroidal satellite galaxies of the Milky Way goes back to an observation already made by Zwicky in the 1950s. He pointed out that galaxies may form anti-hierarchically in the material thrown out off interacting large galaxies. These nowadays called tidal dwarf galaxies (TDG, Mirabel et al. 1992) are well known to form in the Universe (e.g.Weilbacher et al. 2003;Walter et al. 2006). Based on the identification of streams of satellite galaxies and globular clusters on the sky, in a pioneering work Lynden-Bell (1983) had suggested that the dwarf spheroidals originate from the break up of a former larger galaxy. With the growing success of the dark matter theory this idea was, however, often overlooked and dwarf galaxies were naturally identified with accreted cosmological sub-structures. Kroupa et al. (2005) highlighted the issue again deeming the great plane of the MW satellites to be inconsistent with the CDM theory. Indeed, there is a strong correlation of the orbital poles of the satellites (Palma et al. 2002; Metz et al. 2008) suggesting a common origin.
I noticed as well that it was anonymously written. What's up with that? Is everyone afraid to sign their name to something that is ATM? Do mainstreamers actually wield that much power?
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