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MOND (Modified Newtonian dynamics) habitats inside the Solar system

MOND (Modified Newtonian dynamics) habitats inside the Solar system . Jo ã o Magueijo Perimeter Institute, CITA, Imperial College. Based on Bekenstein & Magueijo, astro-ph/0602266. The MOND vs Dark Matter conflict.

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MOND (Modified Newtonian dynamics) habitats inside the Solar system

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  1. MOND (Modified Newtonian dynamics) habitats inside the Solar system João Magueijo Perimeter Institute, CITA, Imperial College Based on Bekenstein & Magueijo, astro-ph/0602266

  2. The MOND vs Dark Matter conflict • Everything outside the Solar system refuses to follow the laws of General Relativity/ Newtonian gravity • Either gravity is fine, but there is an extra source we can’t see: the dark matter. • Or the observations are telling us to modify gravity.

  3. We need a direct detection! • Dark matter searches: the game is over if a dark matter particle is detected! • What is the equivalent “backyard” detection of MONDian behavior?

  4. (Spiral) Galaxy rotation curves: • Flattening of rotation curves • Anomalous behaviour triggered by • Tully-Fisher relation

  5. Take these facts as “Kepler’s laws” for a new theory of gravity • Milgrom’s insight: • A better formulation: (often quoted as a rule of thumb)

  6. What the Solar system needs from MOND: • A modified Poisson equation • (there are several relativistic, Lagrangian formulations leading to this)

  7. Why a direct test? Both approaches have been in turn un/successful • LeVerrier prediction of Neptune from Uranus orbital anomalies (first example of dark matter). • Attemps to explain the anomalous precession of the perihelion of Mercury with “Vulcanus”

  8. A backyard detection of MOND? • Lagrange points? • Saddle points.

  9. Naïve expectation: • MONDian tidal stresses should diverge at the saddle: • Newtonian result: • Take the squareroot:

  10. Outside (perturbative) region • Maximal fractional effect is at the border ellipsoid • Its value is • It then falls off as 1/r^2

  11. The inner region profile • The angular profile is approximately Newtonian • The tidal stress divergence is there but it’s much softer due to the curl term

  12. LISA Pathfinder mission

  13. A target for LPF? • Accelerometers have a sensitivity of • Target region for Sun/Earth saddle has size

  14. CONCLUSIONS • Don’t accuse us of not providing you with a target • Most of other approaches are too fudged to make concrete predictions at this level • If you don’t like the model (I don’t) the solution is simple: KILL IT!

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