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PI Total time #CoIs, team

MOND and DM with the ELT Our best chance to rule out MOND (or DM) comes from globular clusters. I propose to observe a sample of nearby and distant GCs with the aim of (i) understanding their structure in detail, (ii) measuring their velocity dispersions, and (iii) finding their DM content. PI

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PI Total time #CoIs, team

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  1. MOND and DM with the ELT Our best chance to rule out MOND (or DM) comes from globular clusters. I propose to observe a sample of nearby and distant GCs with the aim of (i) understanding their structure in detail, (ii) measuring their velocity dispersions, and (iii) finding their DM content. PI Total time #CoIs, team Marco Lombardi 10n (ELT 42m) ~10 people with competences in high-precision astrometry, stellar dynamics, and gravitational lensing Marco Lombardi 10n (ELT 42m) ~10 people with competences in high-precision astrometry, stellar dynamics, and gravitational lensing Marco Lombardi 10n (ELT 42m) ~10 people with competences in high-precision astrometry, stellar dynamics, and gravitational lensing Marco Lombardi 10n (ELT 42m) ~10 people with competences in high-precision astrometry, stellar dynamics, and gravitational lensing Marco Lombardi 10n (ELT 42m) ~10 people with competences in high-precision astrometry, stellar dynamics, and gravitational lensing

  2. MOND and CDM Structure formation still poorly understood  freedom in the distribution of DM MOND better verifier in objects w/o DM  stronger bounds on Newtonian dynamics Ideal candidates are distant GCs  they have a <a0 ~ 10-8 cm s-2 Idea: observe GCs, understand their structure, and see if MOND works.

  3. Newtonian prediction (virial theorem): 2 = G M / rv  z2 = 0.11 G M / rh • MOND prediction (regime aext < aint < a0) z2 = 0.22 (a0G M)1/2 • For distant GCs the two predictions differ by a factor ~3 Use LOS velocity dispersion measurements of GCs to distinguish the two cases (Baumgardt et al. 2005)

  4. Proposal • Observe a nearby GC with GAIA + ELT to determine its internal structure and compelling evidence of no DM • Measure the structure and vel. dispersion of a distant GC in the MOND regime • Compare the two cases to find if Newtonian or MOND dynamics hold

  5. ELT Justification: observations require extreme astrometry and measurements of individual velocities in the cores of globular clusters. Legacy Value: the same data will be provide (i) a measurement of BH masses in GCs, (ii) accurate (1%) orbital parameters of GCs, (iii) (µ)lensing data in GCs, and (iv) f(r,v) Data Reduction: combined ELT-GAIA analysis required

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