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PRODID:-//eluceo/ical//2.0/EN
VERSION:2.0
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UID:0e12056ba0da132c435e53cbf2696cee
DTSTAMP:20261012T161901Z
SUMMARY:Chemical decoding of kinematic substructures in the Galactic halo
DESCRIPTION:Contact: anastasiia.plotnikova@geol.lu.se\n\nAbstract: In the h
 ierarchical mass assembly framework\, the accretion history of the Milky W
 ay is crucial to understand its evolution. Previous studies have shown tha
 t integrals of motion (such as energy and angular momentum) are not strict
 ly conserved during massive mergers\, leading to a broad redistribution of
  accreted stars across dynamical spaces. Additionally\, part of the in-sit
 u disc component itself becomes kinematically heated and acquires halo-lik
 e orbits as a result of the merger. Consequently\, even for minor mergers\
 , which experience weaker dynamical friction and are then supposed to pres
 erve a higher degree of dynamical coherence\, we expect their kinematic-de
 fined samples to be anyway contaminated by both the massive merger(s) and 
 the disc stars\, thereby hiding the presence of different populations with
 in their samples.This study aims at quantifying these contamination effect
 s in known accreted halo substructures. As they are defined by their kinem
 atics\, we aim at cleaning their samples analysing their chemical properti
 es only\, to uncover their specific abundance patterns.We applied the kine
 matic selection criteria for the halo substructures to the Gaia EDR3 and A
 POGEE DR17 data. Then we adopted a Gaussian Mixture Model (GMM) approach t
 o chemically compare different substructures\, taking into account several
  abundances (Fe\, Mg\, Si\, Ca\, Mn\, Al\, and C). This method incorporate
 s the analysis of various elements that probe different nucleosynthetic ch
 annels\, providing a percentage of global chemical compatibility. At the s
 ame time\, it allows us to perform a comprehensive comparison between two 
 samples of the overall distribution of a given element [X/Fe] vs. [Fe/H].&
 nbsp\;We show that a number of halo substructures feature a high fraction 
 of chemically-compatible stars with respect to the most massive merger of 
 the MW (i.e.\, GSE)\, along with some of them also displaying a non-neglig
 ible contamination from the disc. After removing contamination from both c
 omponents\, we derive the intrinsic chemical patterns of the known accrete
 d halo substructures. We argue that the chemical properties of some halo s
 ubstructures point towards a shared origin with GSE&nbsp\;or at least to a
  very similar chemical evolution history.\n\nMore information about the ev
 ent: https://www.lundobservatory.lu.se/calendar/chemical-decoding-kinemati
 c-substructures-galactic-halo
DTSTART;TZID=GMT:20250902T080000
DTEND;TZID=GMT:20250902T090000
LOCATION:Gotland\, located on the ground floor in the Geocentrum I building
 .
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