The large-scale structure of the halo of the Andromeda galaxy II. Hierarchical structure in the Pan-Andromeda Archaeological Survey
Abstrak
The Pan-Andromeda Archaeological Survey is a survey of $>400$ square degrees centered on the Andromeda (M31) and Triangulum (M33) galaxies that has provided the most extensive panorama of a $L_\star$ galaxy group to large projected galactocentric radii. Here, we collate and summarise the current status of our knowledge of the substructures in the stellar halo of M31, and discuss connections between these features. We estimate that the 13 most distinctive substructures were produced by at least 5 different accretion events, all in the last 3 or 4 Gyrs. We suggest that a few of the substructures furthest from M31 may be shells from a single accretion event. We calculate the luminosities of some prominent substructures for which previous estimates were not available, and we estimate the stellar mass budget of the outer halo of M31. We revisit the problem of quantifying the properties of a highly structured dataset; specifically, we use the OPTICS clustering algorithm to quantify the hierarchical structure of M31's stellar halo, and identify three new faint structures. M31's halo, in projection, appears to be dominated by two `mega-structures', that can be considered as the two most significant branches of a merger tree produced by breaking M31's stellar halo into smaller and smaller structures based on the stellar spatial clustering. We conclude that OPTICS is a powerful algorithm that could be used in any astronomical application involving the hierarchical clustering of points. The publication of this article coincides with the public release of all PAndAS data products.
Topik & Kata Kunci
Penulis (32)
Alan W. McConnachie
Rodrigo Ibata
Nicolas Martin
Annette M. N. Ferguson
Michelle Collins
Stephen Gwyn
Mike Irwin
Geraint F. Lewis
A. Dougal Mackey
Tim Davidge
Veronica Arias
Anthony Conn
Patrick Cote
Denija Crnojevic
Avon Huxor
Jorge Penarrubia
Chelsea Spengler
Nial Tanvir
David Valls-Gabaud
Arif Babul
Pauline Barmby
Nicholas F. Bate
Edouard Bernard
Scott Chapman
Aaron Dotter
William Harris
Brendan McMonigal
Julio Navarro
Thomas H. Puzia
R. Michael Rich
Guillaume Thomas
Lawrence M. Widrow
Akses Cepat
- Tahun Terbit
- 2018
- Bahasa
- en
- Sumber Database
- arXiv
- Akses
- Open Access ✓