Towards Earth mass planets via microlensing. Jean-Philippe Beaulieu, et al. HOLMES & PLANET Collaboration Institut d’Astrophysique de Paris Europlanet Munster

1-7 kpc from Sun Galactic centerSun 8 kpc Light curve Source star and images Lens star and planet Observer Target Field in the Central Galactic Bulge

A planetary companion

Hunting for planets via microlensing Detecting real time microlensing event : OGLE-III and MOA 2 Selecting microlensing event with good planet detection efficiency Two schools : - High magnification events and alerted anomalies (microFUN) - Monitoring a larger number of events (PLANET/ROBONET). Networks of telescopes 24h/24: PLANET/RoboNET, microFUN Accurate photometry (Image subtraction since 2006) Real time analysis and modeling All data, models, are shared immediately among the microlensing community. Cooperation is the way to go ! OGLE-III has an online anomaly detector (EWS) MOA-II Detecting anomalies real time :

PLANET/RoboNet SITES ESO Danish 1.54m Sutherland, SAAO 1m Boyden, 1.5m, CCD 2006, 2007 Perth 0.6m Hobart 1m, Brazil 0.6m, Robonet : Liverpool 2m, Canary Faulkes North 2m, Hawaii Faulkes South 2m, Australia Goals at each site : - 1 % photometry, - Adapted Sampling rate - Online analysis. Boyden 1.5m The sun never rises on the network.

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Members of the PLANET collaboration serving Science

Real time analysis system Data from all site uploaded to Paris every 5 min RoboNet SAAO Boyden Chile Hobart Perth Brasil Data stored in Paris Models updated Predictions Detection efficiencies Alert if anomalies In Out

2 Jupiter mass planets detected microlensing (2004, 2005) : Small fraction of M dwarfs orbited by a Jovian companion

OGLE-2005-BLG-390 Coopération : PLANET/RoboNET, OGLE-III, MOA-II

AT LAST, A TEXT BOOK MICROLENSING EVENT Data in the anomaly from : PLANET-Danish, OGLE, MOA-II, PLANET-Perth Data outside the anomaly from : PLANET/Robonet, PLANET-Hobart Gould Loeb 1992, Bennett & Rhie 1996, …

PROBABILITY DENSITIES OF THE STAR AND ITS PLANET

Gould et al. 2006, MicroFUN, OGLE, RoboNet OGLE-2005-BLG-169Lb:a cold Neptune planet

PLANET Detection efficiency By microlensing : 2 ~Jupiters, 1 ~5.5 Earth, 1 ~13 Earth Gazeous planets are rare, small planets seem to be common Same direction as the core accretion model prediction Beaulieu et al., 2006 Gould et al., 2006 Udalski et al., 2005 Bond et al., 2004

Gaudi et al., 2008, Science A scale ½ solar system : 0.5 Mo, ~0.7 Mjup, ~0.3 Mjup

3 bodies, 0.5 Mo, ~0.7 Mjup, ~0.3 Mjup at 2.3 AU, at 4.6 AU Triple lens, with finite source effects, parallaxe, & taking into account rotation of planets Ultimate nightmare for normal microlensing planet hunters. Great excitment for Gaudi, Bennett, Gould and Dong. Two other multiple systems « in stock », modeling underway. Microlensing gives constraints on multiple planet systems. A scale ½ solar system (Sun, Jupiter, Saturn)

What about Earth mass planets ?

Microlensing of an Earth mass planet If planetary Einstein Ring < source star disk: planetary microlensing effect is washed out (Bennett & Rhie 1996) For a typical bulge giant source star, the limiting mass is ~10 M  For a bulge, solar type main sequence star, the limiting mass is ~ 0.1 M  Earth mass planet signal is washed out for giant source stars To get small mass planets, we need small source stars !

A small super Earth orbiting a very low mass star 2007’s surprise, MOA 2007-BLG-192 VLT Adaptive optics : Light of the lens detected Favored solution : star ~0.09 Mo M  Planet ~1.4 M  Confirmation underway… Bennett et al., 2008 ApJ Beaulieu et al., 2008

Ground-based confusion, space-based resolution Main Sequence stars are not resolved from the ground Systematic photometry errors for unresolved main sequence stars cannot be overcome with deeper exposures (i.e. a large ground-based telescope). High Resolution + large field + 24hr duty cycle

EUCLID (ESA) & MPF (NASA) Refregier et al. 2008, proposal to ESA COSMIC VISION Bennett, et al., 2007 white paper exoplanet task force Bennett, Beaulieu, et al., 2008 JDEM RFI answer Beaulieu et al., 2008 ESA EPRAT white paper Habitable Earth & down to Mars mass planets EUCLID-ML Wide field imager in space

PLANET HUNTING EFFICIENCY WITH EUCLID Monitor stars Color information ~ once a week ~4 square degrees observed every ~20 min each over period of 3 months 3 months dedicatedSensitivity to planets with a 3 months dedicated observing program : –16 frocky rocky planets (Earth, Venus, Mars) –580 fjupiter Jupiter planets –118 fsat Saturn –16 fnep Neptune planets Earth in habitable zone is feasible, but requires statistics (telescope time). The bulk of host system is M and K dwarfs Currently, we estimate that frocky ~30+ %, fJupiter ~ 5%

Transiting planets microlensing Radial velocities Solar system : E = Earth J = Jupiter, N = Neptune…

The near-term: automated follow-up The near-term: automated follow-up 1-5 yr Milestones: A.An optimised planetary microlens follow-up network, including feedback from fully-automated real-time modelling. B.The first census of the cold planet population, involving planets of Neptune to super-Earth (few M ⊕ to 20 M ⊕ ) with host star separations around 2 AU. C.Under highly favourable conditions, sensitivity to planets close to Earth mass with host separations around 2 AU. Running existing facilities with existing operations

The medium-term: wide-field telescope networks The medium-term: wide-field telescope networks 5-10 yr Milestones: A.Complete census of the cold planet population down to ~10 M ⊕ with host separations above 1.5 AU. B.The first census of the free-floating planet population. C.Sensitivity to planets close to Earth mass with host separations around 2 AU. Several existing nodes already. Adding one node in South Africa, + operation : M$

The longer-term: a space-based microlensing survey 10+ yr Milestones: A.A complete census of planets down to Earth mass with separations exceeding 1 AU B.Complementary coverage to Kepler of the planet discovery space. C.Potential sensitivity to planets down to 0.1 M ⊕, including all Solar System analogues except for Mercury. D.Complete lens solutions for most planet events, allowing direct measurements of the planet and host masses, projected separation and distance from the observer. Dedicated ~400 M$, or participation to Dark energy probes Excellent synergy Dark Energy/Microlensing

CONCLUSION Microlensing is today probing “Frozen” planets. 8 microlensing planets published to date : 3 ~Jupiters, 1 ~ 1.4 Earth, 1 ~5.5 Earth, 1 ~13 Earth 1 multiple system : Jupiter + Saturn (Probability of detecting Jupiters is ~30 times larger) Giant planets are rare, suggests 1-15 M EARTH might be common Several planets in “stock”… modeling underway. Frozen ~Earth mass planets on ~AU orbits are within reach yrs : automatic follow up (pointed obs) 5-10 yrs : network of wide field imagers 10+ yrs : wide field imager in space (EUCLID) Getting η super earth, then η 

EUCLID-ML