English

Exploration of Halo Substructures in IoM Space with \textit{Gaia} DR3

Astrophysics of Galaxies 2024-10-10 v1

Abstract

Using kinematic data from the Gaia Data Release 3 catalog, along with metallicity estimates robustly derived from Gaia XP spectra, we have explored the Galactic stellar halo in search of both known and potentially new substructures. By applying the HDBSCAN clustering algorithm in IoM space (i.e. E,LzE,L_{z} and LL_{\perp}=Lx2+Ly2 = \sqrt{L_{x}^2+L_{y}^2}), we identified 5 previously known substructures: Gaia-Sausage-Enceladus (GSE), Helmi Streams, I'itoi + Sequoia and Hot Thick Disc. We additionally found NGC 3201 and NGC 5139 in this work, and NGC 3201 shares similar distributions in phase space and metallicties to Arjuna, which possibly implies that they have the same origin. Three newly discovered substructures are Prograde Substructure 1 (PG1), Prograde Substructure 2 (PG2) and the Low Energy Group. PG1, with a higher VϕV_{\phi} than typical GSE member stars, is considered as either a low eccentricity and metal-rich part of GSE or part of the metal-poor disc. PG2, sharing kinematic similarities with Aleph, is thought to be its relatively highly eccentric component or the mixture of Aleph and disc. The Low Energy Group, whose metal-poor component of metallicity distribution function has a mean value [M/H] \sim -1.29 (compared to that of Heracles [M/H] \sim -1.26), may have associations with Heracles.

Keywords

Cite

@article{arxiv.2410.06646,
  title  = {Exploration of Halo Substructures in IoM Space with \textit{Gaia} DR3},
  author = {Haoyang Liu and Cuihua Du and Dashuang Ye and Jian Zhang and Mingji Deng},
  journal= {arXiv preprint arXiv:2410.06646},
  year   = {2024}
}

Comments

14 Pages, 8 Figure, accepted for publication in ApJ