The formation pathways of compact elliptical galaxies ...

• Main Authors: Deeley, Simon, Drinkwater, Michael, Sweet, Sarah, Bekki, Kenji, Couch, Warrick, Forbes, Duncan
• Format: Text
• Language: unknown
• Published: arXiv 2023
• Subjects: Astrophysics of Galaxies astro-ph.GA; FOS Physical sciences; sami
• Online Access: https://dx.doi.org/10.48550/arxiv.2308.00305; https://arxiv.org/abs/2308.00305

Compact elliptical (cE) galaxies remain an elusively difficult galaxy class to study. Recent observations have suggested that isolated and host-associated cEs have different formation pathways, while simulation studies have also shown different pathways can lead to a cE galaxy. However a solid link has not been established, and the relative contributions of each pathway in a cosmological context remains unknown. Here we combine a spatially-resolved observational sample of cEs taken from the SAMI galaxy survey with a matched sample of galaxies within the IllustrisTNG cosmological simulation to establish an overall picture of how these galaxies form. The observed cEs located near a host galaxy appear redder, smaller and older than isolated cEs, supporting previous evidence for multiple formation pathways. Tracing the simulated cEs back through time, we find two main formation pathways; 32 $\pm$ 5 percent formed via the stripping of a spiral galaxy by a larger host galaxy, while 68 $\pm$ 4 percent formed ... : 18 pages, 15 figures, accepted for publication in MNRAS. Corrected Table 1 ...