Refining the free function of MOND

Workshop Program

Dark Matter

and

Alternative Gravities

Day 1: Galaxies and Solar System

Day 2: Large Scale and Lensing

Day 3: Satellites and Challenges for all theories

Day 1: Galaxies

• The acceleration discrepancy problem

• Large halos of DM

• CDM: Large Scale Structure and best candidate

• Is the missing satellite problem solved?

• How do we solve the cusp problem in CDM?

• Is WDM the solution? (cf. e.g. dSph)

• What about the -WDM cosmological model?

• Wiggles of the rotation curves?

• With DM, how do we explain the « order » encapsulated in the well-known MOND formula? (g/a0) gg = ggN baryons

with (x) = x for x « 1 (MONDian regime) (x) = 1 for x »1 (Newtonian regime)

• Is this going to end as an equivalent of Titus Bode’s law for the solar system?

• If not, could it be the signature of exotic DM somehow interacting with baryons? Are there candidates?

Day 1: Solar System

• Pioneer anomaly: end of gravity as we know it?

• Thermal emission anisotropy of the spacecraft?

• Is acceleration different for different orbits? => Modified Inertia? End of « metric » gravity?

Day 2: Large Scale

• Are massive galaxies at very high redshift a challenge to standard hierarchical model?

• CMB anisotropies: the most serious challenge to any modified gravity theory?

• Galaxy clusters: failure of the MOND formula + lensing of interacting clusters : => surviving « hybrid » theory? (e.g. BSTV)

• Dark Energy: do we know enough about supernovae? (models don’t explode, while they are the only direct evidence)

• Isn’t there too much dark energy in a flat TeVeS Universe, in order to fit supernovae? Running cosmological constant?

• Non-MOND modifications of the left-hand side of Einstein equation? Is unification with DM possible?

Day 2: Lensing

• Is the scatter observed in the lenses gravity vs. lenses baryonic content real, or due to too many uncertainties in the analysis?

• If confirmed, this scatter cannot be fitted by any modified gravity theory

• What about lensing in conformal gravity?

Day 3: Galactic Satellites

• MOND: Dwarf spheroidals need DM if their size is primarily determined by tides, as distant globular clusters are

• Not all internal velocity dispersion profiles of dSph are compatible with the MOND formula (bigger problem than in galaxy clusters)

Day 3: Challenges

• DM: cusps• DM: wiggles of RC’s

• MOND: CMB, galaxy clusters, function (precise M/L could fix and rule TeVeS out)

• E.g. in conformal gravity, how do we handle complex geometries?

• What happens to dynamical friction in any modified gravity theory?

• Can a hybrid theory save e.g. the issue for dSph?

ETC.