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SUMMARY:The stellar halo’s response as a probe of the LMC to MW mass rat
 io
DTSTART;VALUE=DATE-TIME:20230323T082500Z
DTEND;VALUE=DATE-TIME:20230323T084000Z
DTSTAMP;VALUE=DATE-TIME:20241114T092444Z
UID:indico-contribution-187@meetings.aip.de
DESCRIPTION:Speakers: Simon Rozier (Observatoire Astronomique de Strasbour
 g)\nIn the last two decades\, some arguments have accumulated for a more i
 mportant mass ratio of the Large Magellanic Cloud (LMC) to the Milky Way (
 MW) than was previously thought\, of about 10% or more. This implies that 
 the LMC has a measurable influence on the dynamics in the MW stellar halo\
 , including both stellar densities and kinematics\, as observed by Conroy 
 *et al.* (2021) and Petersen *et al.* (2021). While this merger has been p
 reviously reproduced using N-body simulations (see\, e.g.\, Garavito-Camar
 go *et al.*\, 2019)\, I will present the results of a recent study (Rozier
  *et al.*\, 2022) which aimed at modelling the merger via linear response 
 theory. More specifically\, we integrated the linearized collisionless Bol
 tzmann-Poisson system of partial differential equations using a methodolog
 y known as the matrix method. Our results display the same large scale beh
 aviour as state-of-the-art simulations\, with a dipolar over/underdense pa
 ttern related to the reflex motion of the MW\, as well as an overdense wak
 e trailing behind the LMC. These results represent an efficient way of con
 straining the LMC to MW mass ratio\, since this ratio is directly proporti
 onal (given the linear nature of the theory) to the amplitude of the relat
 ive density variations of the MW stellar halo\, both in physical and in ph
 ase space. However\, the amplitude of these variations may also depend on 
 some model parameters\, such as the structure of the MW potential (includi
 ng a possible dark matter component)\, the initial density distribution of
  the stellar halo\, as well as its initial internal kinematics. I will foc
 us on the latter source of degeneracy\, showing how the initial velocity a
 nisotropy of the stellar halo impacts its response to the LMC. Interesting
 ly enough\, it appears that the physical space density of the (dipolar) re
 flex motion is insensitive to the stellar halo’s initial velocity anisot
 ropy\, and can therefore represent an efficient probe of the LMC to MW mas
 s ratio.\n\nhttps://iaus379.aip.de/event/20/contributions/187/
LOCATION:Haus H\, Telegrafenberg
URL:https://iaus379.aip.de/event/20/contributions/187/
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