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SUMMARY:Internal proper motions of dwarf spheroidal galaxies: Constraining
  the density and properties of dark matter
DTSTART;VALUE=DATE-TIME:20230320T114500Z
DTEND;VALUE=DATE-TIME:20230320T114700Z
DTSTAMP;VALUE=DATE-TIME:20241114T092410Z
UID:indico-contribution-228@meetings.aip.de
DESCRIPTION:Speakers: Eduardo Vitral (Space Telescope Science Institute)\n
 Determination of the mass density profiles of dwarf galaxies (and specific
 ally whether there is a central core or cusp) provides a critical test of 
 both the properties of dark matter (DM) and the physics of cosmological st
 ructure formation. The nearby classical dwarf spheroidal galaxies (dSphs) 
 of the Milky Way yield some of the best dynamical constraints. While large
  line-of-sight velocity datasets exist (some thousand stars per galaxy)\, 
 interpretation is hindered by the well-known mass vs. velocity-anisotropy 
 degeneracy of stellar dynamics. This can be resolved with proper motion (P
 M) measurements that yield 3-D velocity information\, which is beyond the 
 reach of Gaia\, given the small velocity dispersions of dSphs and the abse
 nce of bright stars. To attain the necessary precision and a proper handli
 ng of systematics for this kind of study\, one then needs not only longer 
 baselines\, but the combination of many fields from different state-of-the
 -art telescopes. We thus obtain separate PMs from the nearby Draco and Scu
 lptor dSphs from 3 epochs of HST data for 5 fields\, from 2 epochs of new 
 JWST observations of these same fields as well as two additional fields\, 
 all of which are further compared to Gaia DR3 positions. From this long-te
 rm program we will be able to provide a direct determination of their velo
 city anisotropy profiles\, and combined with dynamical models\, tightly co
 nstrain the slopes of their DM density profiles. No comparable measurement
 s exist to date\, and the precision attainted will be fundamental to lay m
 ore robust constraints on both the nature of DM\, and the physical mechani
 sms that shape DM density profiles in galaxies. We will discuss the progre
 ss of our program\, and some initial results from the observational epochs
  and data obtained to date. Additional observations to be obtained through
  2025 will yield the final accuracies needed for our goals.\n\nhttps://iau
 s379.aip.de/event/20/contributions/228/
LOCATION:Haus H\, Telegrafenberg
URL:https://iaus379.aip.de/event/20/contributions/228/
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