The Andromeda Galaxy’s Last Major Merger: Constraints from the survey of Planetary Nebulae

Souradeep Bhattacharya, Magda Arnaboldi, Ortwin Gerhard, Nelson Caldwell, Chiaki Kobayashi, Francois Hammer, Yanbin Yang, Kenneth C. Freeman, Johanna Hartke, Alan McConnachie

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Abstract

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 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.
Original languageEnglish
Title of host publicationIAUS 377: Early Disk-Galaxy Formation from JWST to the Milky Way
PublisherThe International Astronomical Union
Pages1-5
Number of pages5
Publication statusPublished - 4 May 2023
EventIAUS 377: Early Disk-Galaxy Formation from JWST to the Milky Way - Kuala-Lumpur, Malaysia
Duration: 6 Feb 202310 Feb 2023
https://www.mso.anu.edu.au/~yting/Malaysia_IAU/

Conference

ConferenceIAUS 377: Early Disk-Galaxy Formation from JWST to the Milky Way
Country/TerritoryMalaysia
CityKuala-Lumpur
Period6/02/2310/02/23
Internet address

Keywords

  • astro-ph.GA
  • astro-ph.SR

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