1. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Microlensing search for extra-solar planets from Dome C Arnaud Cassan Astronomisches Rechen-Institut (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH) J.-P. Beaulieu, P. Fouqué, J.-B. Marquette, C. Coutures

2. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Outline 1/ The microlensing method 2/ The current observing setup 3/ Results and capabilities of the method 4/ Why observing from Dome C ? 5/ Summary & conclusion

3. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 The Gravitational microlensing effect ► Magnification of the source star flux Probing the Galactic Halo (MACHO, EROS) Galactic structure (OGLE, MACHO, EROS) Search for extra-solar planets (PLANET, MOA, MicroFun)

4. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Observations toward the Bulge Probability of a microlensing event : 10 -6  observations toward the Bulge OGLE fields Dome C is definitely the best site to observe the Bulge from Earth

5. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Image separation : Einstein radius crossing time : Maximum amplification :  unresolved images !  Flux magnification monitoring 3 - 4 weeks continuous observations from Dome C

6. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 The « standard » multi-site setup: a network of telescopes Ongoing microlensing events alerted by OGLE, MOA (EROS, MACHO) Days Follow-up network : PLANET collaboration

7. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 ”Homebase” : - light curves modeling - observational strategy - public alerts - anomaly predictions Observatories Raw data ( on-line reduction ) Data reduction pipeline Observational strategy BUT requires many “manual” operations…  One site allow much more automated procedures, from data reduction to data analysis and modeling

8. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 MOA 2003-BLG-53Lb : a Jupiter-like planet

9. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 OGLE-2005-BLG-071Lb : another Jupiter-like planet

10. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 OGLE-2005-BLG-390Lb a 5.5 Earth-mass planet

11. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 OGLE-2005-BLG-169Lb : a weak Neptune plant signal Gaps in the coverage  difficulties in modeling and finding a unique model

12. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Detection efficiencies Cassan et al., 2006, en préparation  [1] Modeling of individual events, e.g. :  [2] Statistical combination of the individual efficiencies

13. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Microlensing detection efficiencies 1995 - 2006 Cassan et al., 2006, en préparation These planets of few Earth masses and few AU orbits may be very common A continuous monitoring from Dome C would push the detection efficiency limits toward low-mass stars

14. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Limits on abundance of exoplanets No strong selection with star brightness (only the lens mass is involved) The « whole » range of star mass is probed (prop. to their abundance) Gaudi et al. 2000 Ultimately, microlensing can provide a good estimation of Galactic planet abundance

15. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Multiple planetary systems Kubas, Cassan et al. (in preparation) Ex. Constraints on additional Jupiter-like planets on OGLE-2005-BLG-390

16. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Complementary to other methods

17. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Main goals of microlensing Detection of Neptune to Earth-mass planets Abundance of extra-solar planets in the Galaxy From space simulations (MPF satellite, Bennett et al. 2005) : –66 terrestrial planets –100 icy giants –3300 gas giants  Order of magnitude of what may be expected from Dome C

18. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Why Dome C ? With he current setup : –Gaps in the light curve –Multi-site photometry = difficulties with combining data sets from different telescopes (mean seeing/air mass, weather conditions, CCDs…) –Australia do not provide stable weather conditions to operate a deep round-the-clock monitoring  Only 1 terrestrial planet so far Given that : - the theoretical efficiency is higher than is achievable now - the main difficulties come from -the non-continuous monitorin -The weather conditions - the statistical point of view is the most relevant for microlensing search for exoplanets ► The ground base detection capabilities have been reached ► Dome C is the most relevant site to achieve the ultimate goal of microlensing searches for exoplanets = statistical aspect

19. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 What would Dome C provide for microlensing towards the Bulge ? Continuous monitoring of the Bulge Stable weather condition  eliminate false alerts Stable and good seeing, low background One telescope with one instrument  high improvement of photometry precision + known systematic errors

20. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 A possible setup A 2m-class telescope 28k x 28k camera 0.09 ” /pixel -> 0.5deg 2 FOV FWHM 0.25 ’’ 2 deg 2 monitored in the Bulge Time Sampling : every 20 min During Antarctica winter season: in 2005 (sun 81 days 3 – 4 weeks continuous observations (time scale < 30 d) A OGLE-like alert + following setup

21. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Summary & Conclusion 4 extra-solar planets discovered : –2 Jupiter-like + 1 Neptune planets (2003-2006) –A 5.5 Earth-mass planet (2006) Abundance of exoplanets around M-dwarfs –will ultimately extend to “all” stars Sensitivity/limits on multi-planetary systems Complementary to other techniques (ex. RV) Dome C is the only site on Earth that allows a continuous monitoring of the Galactic Bulge A realistic project : –Experience from an ongoing project (10 years with PLANET) –Expertise of data reduction/image subtraction technique –Expertise in modeling, statistical analysis

22. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006

23. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Magnification: u Magnification curves Einstein ring radius: (t-t 0 )/t E The single lens case

24. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Model predictions vs. microlensing observation OGLE 2005-BLG-390Lb Ida & Lin, 2005, ApJ 246, 1045 Cassan & kubas (in preparation)

25. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Crowded fields

26. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Galactic microlensing

27. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006

28. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Beaulieu et al., 2006, Nature 439, 437 31.7.05 10.8.05 OGLE 2005-BLG-390Lb : a cool 5.5 Earth-mass planet

29. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006

30. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 What we know from the unique modeling Planet/star mass ratio : q = m p / M * = (7.6 ± 0.7) x 10 -5 Instantaneous separation/Re : d = r phys / R E = 1.61 ± 0.01 Source star distance : D S = 8.5 kpc Einstein ring crossing time : t E = 11.0 ± 0.1 days R E = v t t E = 1/c [ 4GM * D L (1-D L /D S ) ] 1/2

31. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 The mass of OGLE 2005-BLG-390Lb

32. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006

33. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006

34. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Deriving physical parameters Planet mass & orbit : m p = 5.5 +5.5 -2.7 Earth-mass a p = 2.6 +1.5 -0.6 AU Host star : M * = 0.2 +0.2 -0.1 M sol Lens distance : D L = 6.6 ± 1 kpc

35. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Détection des exoplanètes Juillet 2003 (Planète jovienne) Mai 2005 (Planète jovienne) Bond et al., 2004, ApJ 606 Udalski et al., 2005, ApJ 628

36. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 Microlentilles doubles : caustiques et courbes critiques Caustiques (plan-source)Courbes critiques (plan-lentille) intermédiaire Séparation :grande faible

37. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 The microlensing effect Observer lens planesource plane Source < mas Image

38. Arnaud Cassan Optical and Infrared Wide-Field Astronomy in Antarctica ARI / ZAH Heidelberg IAP, 14 – 16 June 2006 The PLANET collaboration (Probing Lensing Anomalies NETwork) M. D. Albrow, J.P. Beaulieu, D. Bennett, S. Brillant, J. A. R. Caldwell, H. Calitz, A. Cassan, K. Cook, C. Coutures, M. Dominik, J. Donatowicz, D. Dominis, P. Fouqué, J. Greenhill, K. Hill, M. Hoffman, K. Horne, U. Jorgensen, S. Kane, D. Kubas, R. Martin, J. Menzies, P. Meintjes, K. R. Pollard, K. C. Sahu, J. Wambsganss, A. Williams ARI Heidelberg (Germany), IAP Paris (France), Univ. of Notre Dame (USA), Univ. of Canterbury (New Zealand), SAAO (South Africa), Boyden Observatory (South Africa), Canopus Observatory (Tasmania), Niels Bohr Institute (Denmark), Univ. of Potsdam (Germany), STSI (USA), Perth Observatory (Australia), ESO (Chile), OMP (France)