Transcript Slide 1
PLANET/Robonet : searching for low mass extra solar planets via microlensing. Jean-Philippe Beaulieu, Institut d’Astrophysique de Paris Target Field in the Central Galactic Bulge Galactic center 8 kpc Sun 1-7 kpc from Sun Light curve Source star and images Lens star and planet Observer A planetary companion tE 20 j, M 0.3 M sun : tp q t E Jupiter: q 3 10-3 t p 1 j T erre: q 105 t p 1.5 h Hunting for planets via microlensing Detecting real time microlensing event : OGLE-III and MOA 2 Detecting anomalies real time : Networks of telescopes to do 24 hours monitoring : PLANET/RoboNET, microFUN Accurate photometry (Image subtraction since 2006) Real time analysis and modeling OGLE-III has an online anomaly detector (EWS) MOA-II Selecting microlensing event with good planet detection efficiency Two schools : - Mainly high magnification events and alerted anomalies (microFUN) - Monitoring a larger number of events (PLANET/ROBONET) All. data, models, are shared immediately among the microlensing community. Cooperation is the way to go ! PLANET collaboration : Probing Lensing Anomaly NETwork (current members) http://planet.iap.fr Boyden 1.5m M. D. Albrow, J.P. Beaulieu, D. Bennett, D. Bramich, 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, Y. Tsapras,J. Wambsganss, A. Williams, M. Zub Institut d'Astrophysique de Paris, INSU CNRS, Paris, France Univ. of Canterbury, Dept. of Physics & Astronomy, Christchurch, New Zealand South African Astronomical Observatory, South Africa Boyden Observatory, Bloemfountein, South Africa Canopus observatory, Univ. of Tasmania, Hobart, Australia Niels Bohr Institute, Copenhagen, Denmark Univ. of Potsdam, Potsdam, Germany Space Telescope Science Institute, Baltimore, U.S.A. Perth Observatory, Perth, Australia PLANET/RoboNet SITES Boyden 1.5m ESO Danish 1.54m 2003-2008 Sutherland, SAAO 1m 2002+ Boyden, 1.5m, CCD 2006, 2007 Perth 0.6m 2002-2007+ Hobart 1m, 2002-2007+ Brazil 0.6m, 2007+ Robonet : Liverpool 2m, Canary 2005+ Faulkes North 2m, Hawaii 2006+ Faulkes South 2m, Australia 2007+ Goals at each site : - 1 % photometry, - Adapted Sampling rate - Online analysis. OBSERVING STRATEGY, DECISION TAKING Homebase checks : - OGLE, MOA alert pages - results from Bayesian PSPL fits to OGLE data (Albrow) - results from K.Horne priority pages - data collected by PLANET/RoboNet and current fits He can ask for data to be re-reduced to double check anomalies. Then he decides an observing strategy, sampling rates for different events He issues anomaly alerts to the community. Homebase should be on the deck 24 hours a day for 2-3 weeks PLANET DATA PROCESSING At each site : -relative photometry for all stars real time - keep an eye on light curve of prime target Data from all sites are uploaded to Paris (every ~10 min) : RoboNet SAAO Boyden Chile Every day, homebase checks : data, light curve fits, BAP, StAndrews priorities algo, Choose strategy, sampling, … Alert the community if anomalies Hobart Perth OGLE-2005-BLG-390 ????????? ???????? ! ! ! A bump in the night… a planet ?????? A binary lens ?????? A planet ! OGLE-2005-BLG-390 Coopération : PLANET/RoboNET, OGLE-III, MOA-II AT LAST, A TEXT BOOK MICROLENSING EVENT Gould Loeb 1992, Bennett & Rhie 1996, … Data in the anomaly from : PLANET-Danish, OGLE, MOA-II, PLANET-Perth Data outside the anomaly from : PLANET/Robonet, PLANET-Hobart PROBABILITY DENSITIES OF THE STAR AND ITS PLANET A companion to this frozen super Earth ? Kubas et al., 2007 submitted Excluding at : 50 % Jupiter over 1.1-2.3 AU 70 % 3 Jupiter over 1.5-2.2 AU Core accretion models by Idal & Lin OGLE-2005-BLG-169Lb : a weak Neptune planet signal Gould et al. 2006, MicroFUN, OGLE, RoboNet A new Jovian analogue a resonnant caustic system 45 5 microlensing planets, their time scale. KB-07-197 Do gas giants prefer host stars that cause longer events ? Ie more massive ones ? Current status of microlensing planet hunting PLANET/Robonet/HOLMES (network of 9 telescopes). Now – 200? MicroFUN Now-200? OGLE III and MOA-2 - Constraints on Jupiters and low mass planets (down to few Earth mass) - Monitoring of high mag events PLANET/RoboNet, MicroFUN, OGLE, MOA - Monitoring of any mag events (PLANET/RoboNet, OGLE) Las cumbres plans ? A 1m observing in J from Antartica ? Network of wide field imager Earth Hunter + OGLE-IV + MOA-2 2011+ ? Statistics on Cool Earth mass planets, possibly habitable zone. NASA mission MPF ( PI Bennett) to be re-submitted ? ESA DUNE mission (cosmic shear + 3 months/Yr of planet search ) Abundance of planets in habitable zone. MPF : 36 months, 200 million stars, 4 fields of 0.66 sq2, FWHM=0.25 arcsec ~100 q Earth, ~6000 q Jupiter (q fraction of stars with planets), Mars detectable Operational remarks 1995-2007 Small dedicated telescopes, with very dedicated people. Retired people, volunteers, important financial supporters (David Warren) Enthusiasm, dedication and friendship among a core part of PLANET. Good image quality Good and stable CCD cameras Well sampled PSF (4 pix in FWHM is excellent) Size of telescope does not matter that much Real time online analysis is vital : The Hummer approach : 1996-2005 PLANET pipeline (PSF fitting) The Ferrari approach : WISIS, image subtraction techniques (since 2006) 3 different image sub pipelines (WISIS, pySIS, DIA-robonet) Coordination effort : sharing/combining all data on short time scales Automatic tools for efficient prediction of behavior of microlens events Fits, predictions of high mag, detection efficiency calculations Experienced guys on the mountains, with support from dedicated people in office. CONCLUSION Operating a network of telescopes for 12 years. 5 microlensing planets for 3 scenarios : •2 Strong caustic •2 High mag central caustic • 1 Planetary caustic 3 ~Jupiters, 1 ~5.5 Earth, 1 ~13 Earth (Probability of detecting Jupiters is ~50 times larger) Giant planets are rare, suggests 1-15 MEARTH might be common Giant planets in events with large tE ? ~Earth mass planets on ~AU orbits to be discovered soon… 1996, sensitivity to Earths depends on source size Earth mass planet signal is washed out for giant source stars 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 Need to monitor small stars to get low mass planets. Using high magnification events, Griest & Safizadeh 1998 « We show that by focusing on high-magnification events, the probability of detecting planets of Jupiter mass or greater in the lensing zone [(0.6 1.6)RE] is nearly 100%, with the probability remaining high down to Saturn masses and substantial even at 10 Earth masses. » Planetary caustic Central caustic Detection ≠ characterization