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SUMMARY:The phase mixed debris of a massive merger as a dark matter subhal
 o detector - Elliot Davies
DTSTART:20221130T131500Z
DTEND:20221130T140500Z
UID:TALK193414@talks.cam.ac.uk
CONTACT:107642
DESCRIPTION:Recent work uncovered features in the phase space of the Milky
  Way’s stellar halo which may be attributed to the last major merger. Wh
 en stellar material from a satellite is accreted onto its host\, it phase 
 mixes and appears finely substructured in phase space. For a high-eccentri
 city merger\, this substructure most clearly manifests as numerous wrappin
 g chevrons in (𝑣𝑟 \, 𝑟) space\, corresponding to stripes in (𝐸
 \, 𝜃𝑟 ) space. We introduce the idea of using this substructure as a
 n alternative subhalo detector to cold stellar streams. We simulate an N-b
 ody merger akin to the Gaia Sausage / Enceladus and assess the impact of s
 ubhaloes on these chevrons. To quantify the impact of perturbers\, we util
 ise the simpler appearance of the chevrons in (𝐸\, 𝜃𝑟 ) space. We
  show that a single flyby of a massive (~ 1010 M⊙) subhalo with pericent
 re comparable to\, or within\, the chevron’s apocentre smooths out the s
 ubstructure\, whereas a single flyby of a low mass (~ 108 M⊙) has neglig
 ible effect. The effects of known massive perturbers (e.g. Sagittarius) co
 uld be detectable and offer constraints on their initial mass.
LOCATION:The Hoyle Lecture Theatre + Zoom 
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