Conceived problems with microlensing : Seems complicated… and hence results suspect…

1. Microlensing planet surveys: the second generation Dan Maoz Tel-Aviv University with Yossi Shvartzvald, OGLE, MOA, microFUN

5. Conceived problems with microlensing: • Seems complicated… • and hence results suspect… • No “follow up” of planets possible • 4. Statistically useless due to haphazard survey strategies • 5. Planet yield so small -- not worth trouble?

6. a R

7. I E S DLS DOL DOS a R

8. “microlensing” (in our Galaxy): In distant galaxies: “macrolensing”, “galaxy lensing”: cluster lensing:

9. I E S DLS DOL DOS a R

10. I+ S + b A - I- DLS DOL DOS a R I+S + SA = I+A

11. ~milliarcsec

12. Magnification=image area / source area : magnification ~ 1/ (impact parameter)

13. Einstein-ring crossing timescale: t =E DOL / v ~ M1/2 S. Gaudi • ForDOL=8 kpc, • v=20 km/s • t(1Msun) = 2 months • t(1MJ)=2 days

14. The first microlensing lightcurves (LMC) Alcock et al. 1993

15. Nowadays, ~1000 microlensing events/yr detected toward Galactic bulge Yee+ 09

17. Bond et al. 2004

18. Beaulieu et al. 2006

19. Udalski et al. 2005

20. Gould et al. 2006

21. Gaudi et al. 2008 “Jupiter”+”Saturn” system: 1+2+3+5=“Saturn”, 4=“Jupiter”

22. Our solar system: 5.2 AU 9.5 AU 1 Msun 1 Mjup 1 Msat Msat/Mjup = 0.30 Rjup/Rsat = 0.55 Mc/Mb = 0.37 Rb / Rc = 0.50 OGLE-2006-BLG-109L,b,c: 2.3 AU 4.6 AU 0.50 Msun 0.71 Mjup 0.90 Msat

23. Second 2-planet system discovered: 0.7MJ (4.6 AU) and 0.1MJ (3.8 AU) Han+2012, OGLE-2012-BLG-0026

24. Simulation by S. Gaudi

25. Simulation by S. Gaudi

26. q = Mp / Mhost Simulation by S. Gaudi

27. Caustics: points in the source plane which get infinite magnification. For a point lens, caustic is a single point behind the lens. (source there gets magnified into Einstein ring)

29. Caustic cusps

30. Magnification still ~ 1/(distance to caustic)

32. Source passage on or near central caustics: high mag  almost full Einstein ring  ~100% detection efficiency for planets near Einstein radius (lensing region). planetary caustics: low mag  Lower planet detection efficiency per event, but much more common. A. Cassan

33. Microlensing probes a unique region of planetary parameter space… Gould et al. 2006, 2009

34. …near the Einstein radii of stars ~ their snow lines. Gould et al. 2006, 2009 Snowline scaling with mass: star

35. Snowline-region planet frequency based on microlensing discovery statistics: Gould et al. (2010, based on 6 planets): ~1/3 of stars have snowline-region planets; ~1/6 of stars have solar-like planetary systems; Cassan et al. (2012, based on 2 (!) planets): ~1/6 host jupiters ~1/2 host neptunes ~2/3 host super-earths

36. To date, only ~20 microlensing planets. Why so few? “1st Generation” survey strategy (Gould & Loeb 1992) focused on bright, high-magnification (mag>100) events.

37. Udalski et al. 2005 Gould et al. 2006 Gaudi et al. 2008

38. 1st Generation microlensing • low cadence (~ once a night) OGLE, Chile, 1.3m MOA, NZ, 1.8m

39. 1st Generation microlensing

40. 1st Generation microlensing ~ 650 events/year

41. 1st Generation Microlensing Follow-up search for planetary perturbations with global network on bright, high-magnification events:

42. High-magnification (mag >100) events are: Good: ~100% sensitivity to planets projected near Einstein radius, + high S/N light curves even with small and amateur telescopes. Bad: Rare events (~1%)  ~7 events/year  1-2 planets/year.

43. As opposed to high-mag (central caustic) events, Low-magnification (planetary caustic) events: Lower planet detection efficiency, but much more common: Potential for tens of microlensing planets/year. A. Cassan

44. Beaulieu et al. 2006

45. Need network of 1-2m class telescopes with degree-scale imagers for continuous monitoring of many low-mag events in search of planetary perturbations: “Generation II microlensing”

46. Since 2011: A generation-II microlensing experiment: Wise Obs., Israel, D=1m, 1 deg2 Yossi Shvartzvald is there OGLE IV, Chile, D=1.3m, 1.4 deg2 MOA-II, NZ, D=1.8m, 2.3 deg2

47. The generation-II network

48. The generation-II network

49. The generation-II network

50. The generation-II network