B3 Non-refereed article in a conference publication
The Andromeda Galaxy’s Last Major Merger: Constraints from the survey of Planetary Nebulae
Authors: Bhattacharya, Souradeep; Arnaboldi, Magda; Gerhard, Ortwin; Caldwell, Nelson; Kobayashi, Chiaki; Hammer, Francois; Yang, Yanbin; Freeman, Kenneth C.; Hartke, Johanna; McConnachie, Alan
Editors: Tabatabaei, Fatemeh; Barbuy, Beatriz; Ting, Yuan-Sen
Conference name: Symposium of the International Astronomical Union
Publisher: Cambridge University Press (CUP)
Publication year: 2024
Journal: Proceedings of the International Astronomical Union
Book title : Early Disk-Galaxy Formation from JWST to the Milky Way
Volume: 18
First page : 123
Last page: 126
ISSN: 1743-9213
eISSN: 1743-9221
DOI: https://doi.org/10.1017/S1743921323000996
Publication's open availability at the time of reporting: No Open Access
Publication channel's open availability : Partially Open Access publication channel
Web address : https://doi.org/10.1017/s1743921323000996
The Andromeda galaxy (M 31) has experienced a tumultuous merger history as evidenced by the many substructures present in its inner halo. We use planetary nebulae (PNe) as chemodynamic tracers to shed light on the recent merger history of M 31. We identify the older dynamically hotter thicker disc in M 31 and a distinct younger dynamically colder thin disc. The two discs are also chemically distinct with the PN chemodynamics implying their formation in a `wet' major merger (mass ratio ∼ 1:5) ∼ 2.5-4.5 Gyr ago. From comparison of PN line-of-sight velocities in the inner halo substructures with predictions of a major-merger model in M 31, we find that the same merger event that formed the M 31 thick and thin disc is also responsible for forming these substructures. We thereby obtain constraints on the recent formation history of M 31 and the properties of its cannibalized satellite.
Funding information in the publication:
SB is funded by the INSPIRE Faculty award (DST/INSPIRE/04/2020/002224), Department of Science and Technology (DST), Government of India. SB acknowledges support from the IMPRS on Astrophysics at the LMU Munich during his PhD.
