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SUMMARY:Lopsidedness in Andromeda's satellite galaxy distribution: A renew
 ed tension with CDM simulations
DTSTART;VALUE=DATE-TIME:20230322T112500Z
DTEND;VALUE=DATE-TIME:20230322T114000Z
DTSTAMP;VALUE=DATE-TIME:20241114T092437Z
UID:indico-contribution-196@meetings.aip.de
DESCRIPTION:Speakers: Kosuke Jamie Kanehisa (Leibniz-Institut für Astroph
 ysik Potsdam)\nDwarf satellite galaxies around Andromeda (M31) and the Mil
 ky Way form thin\, coherently rotating planes argued to be in tension with
  expectations from the cold-dark-matter (CDM) model of cosmology. For M31\
 , this disagreement is compounded by a prominent asymmetry in its satellit
 e distribution\; over 80% of its dwarfs lie in the hemisphere facing the M
 ilky Way. To a degree\, lopsided dwarf galaxy systems appear to be ubiquit
 ous in the local Universe and may reflect an underlying asymmetry in their
  hosts' dark matter halo morphology - in turn carrying implications for ha
 lo mass estimates derived from satellite dynamics. Adopting a recently pub
 lished set of homogeneous\, RR Lyrae-based distances to the M31 satellites
 \, we discovered that the existing asymmetry is strengthened. 34 out of 35
  satellites are contained within a cone with an opening angle of 202 degre
 es (or 213 degrees facing the Milky Way)\, while the luminous dwarf M110 d
 ominates the nearly hemispheric void on the other side. We further studied
  the rarity of similarly asymmetric dwarf galaxy distributions in several 
 state-of-the-art cosmological simulations. Even when accounting for the lo
 ok-elsewhere effect in selecting a preferred opening angle\, less than 0.4
 % of M31 analogs host satellite systems that match or exceed the observed 
 asymmetry. The significance of the M31 satellites' observed asymmetry towa
 rds the Milky Way in CDM simulations now rivals that of M31's plane-of-sat
 ellites\, cementing the Andromeda system as a striking outlier from cosmol
 ogical expectations.\n\nhttps://iaus379.aip.de/event/20/contributions/196/
LOCATION:Haus H\, Telegrafenberg
URL:https://iaus379.aip.de/event/20/contributions/196/
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