What can the asymmetric Andromeda Giant Stream reveal about its progenitor’s rotation?

N-body models test whether a rotating disc dwarf can generate the stream’s asymmetric surface-brightness profile.

Formation of the Andromeda giant stream: asymmetric structure and disc progenitor

Formation of the Andromeda giant stream: asymmetric structure and disc progenitor. Kirihara, Takanobu; Miki, Yohei; Mori, Masao; Kawaguchi, Toshihiro; Rich, R. Michael, Monthly Notices of the Royal Astronomical Society, 464, 3509–3525 (2017).

arXiv:1603.02682 Publication · DOI

Approach

The progenitor disc thickness, rotation speed and orientation are varied systematically while comparing the giant stream and shell structures with observations.

Main result

Progenitor rotation strongly controls the debris morphology. The simulations reproduce the stream and two shells and predict further spatial and metallicity signatures.

Scientific implications

Stream cross-sections can retain information about the internal structure of a galaxy after it is disrupted.

Scope and limitations

The predicted extra shell and surviving-core signatures require observational tests. A successful model need not uniquely fix the progenitor.