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Twenty Years of Microlensing Observations From the

Twenty Years of Microlensing Observations From the. Perspective. Andrzej Udalski Warsaw University Observatory. Bohdan Paczyński (1940—2007). Gravitational Microlensing toward the Galactic Bulge. Planetary Microlensing. Search for Gravitational Microlenses.

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Twenty Years of Microlensing Observations From the

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  1. Twenty Years of Microlensing Observations From the Perspective Andrzej Udalski Warsaw University Observatory

  2. Bohdan Paczyński (1940—2007)

  3. Gravitational Microlensing toward the Galactic Bulge

  4. Planetary Microlensing

  5. Search for Gravitational Microlenses • MACHO Project – Mt. Stromlo, Australia (1992 – 1999) • EROS Project – ESO, Chile (1992 – 2002) • MOA Project – Mt. Johns, New Zealand (1997– …) • OGLE Project – Las Campanas, Chile (1992 – …)

  6. Twenty One Years of the OGLE Survey

  7. OGLE: The Optical Gravitational Lensing Experiment (1992 - ….)Four Phases of the OGLE Project • OGLE-I (1992-1995). 1 m Swope telescope at LCO. ~2 million stars observed. Microlensing • OGLE-II (1997-2000). 1.3 m Warsaw telescope. ~40 million stars observed. Variable and non-Variable Stars in GB, MC • OGLE-III (2001– 2009). 8k x 8k mosaic CCD. ~200 million stars observed (GB, GD, MC). Extrasolar Planets, Microlensing • OGLE-IV (2010– ….). 32-chip 256 Mpixel mosaic CCD http://ogle.astrouw.edu.pl

  8. Las Campanas Observatory, Chile

  9. Discovery of the First Microlensing Events – September 1993

  10. OGLE-I #1 Microlenses: Discovery of the first events toward the GB (1993).

  11. First Binary Microlensing (1994)

  12. Fine Microlensing Effects

  13. Early Warning System (EWS – 1994)

  14. Follow-Up Microlensing Projects < 2001 • PLANET • GMAN • MOA >= 2001 • microFuN • PLANET • Robonet • MindSTEP

  15. Three Main Channels • Search for Dark Matter • Galactic Structure • Extrasolar Planets – Planetary Microlensing

  16. Dark Matter – MACHO in the Galactic Halo

  17. OGLE-2005-SMC-001

  18. OGLE MC Microlensing

  19. Current O-IV MC Survey – 600 square degrees

  20. Classical Cepheids in the Magellanic Clouds SMC LMC Magellanic Bridge

  21. RR Lyrae Stars in the Magellanic Clouds SMC Magellanic Bridge LMC

  22. Stellar Populations in the Magellanic Bridge

  23. OGLE-IV Transient Detection System

  24. Galactic Structure • Optical depth for microlensing toward CG • High resolution spectroscopy of highly microlensed bulge dwarfs • Microlensing in the Galactic disk

  25. 3.2±0.8 (OGLE3 2007) 2.4±0.4 (MACHO 2000) 2.6±0.8 (MOA 2003) Gravitational Microlensing Optical Depth • probably the best way to constrain the internal structure of the Milky Way • The recent models of the Galactic Bulge: Kerins,Robin,Marshall (2010) • OGLE >~10000 microlenses

  26. Optical Depth

  27. Microlensing in the Galactic Disk

  28. OGLE-IV Galactic Disk (l<0)

  29. Planetary Microlensing

  30. OGLE-III Hardware and Software (2001) • 1.3 m OGLE telescope at Las Campanas Observatory, Chile • 8192 x 8192 pixel mosaic CCD camera (0.26 arcsec/pixel scale): 0.5 x 0.5 sq. degree • Data Pipeline: photometry derived with image subtraction method (accuracy up to 3 mmag for the brightest stars over a few months long observing run)

  31. Transiting OGLE Exoplanets

  32. Planetary Microlensing O-III ~600 microlensing events per year in real time since 2002. Short-lived anomaly in the light curve of a typical single mass microlensing event.

  33. OGLE-2003-BLG-235/MOA-2003-BLG-53First Planetary Microlensing Planet/star mass ratio: q~0.004

  34. OGLE-2005-BLG-71 Planet/star mass ratio: q~0.007

  35. OGLE-2005-BLG-390 Planet/star mass ratio: q~0.00008. Mass of the planet: ~6 Earth masses. The least massive planet at the discovery

  36. MOA-II Survey (2006– …)

  37. Microlensing Planets – results • ~30 microlensing planets found since the first announcement in 2004 (~20 published so far) • First cool super-Earths of 3-10 Earth masses: low mass planets are common • OGLE-2006-BLG-109: analog of the solar system (multiplanetary system: Jupiter+Saturn like) • First estimations of the frequency of planets at and behind the „snow line” • 2003– 2007: the discovery rate 0-1 exoplanets per season • 2007–2010: the discovery rate of 2-4 exoplanets per season

  38. Main Potential of Microlensing • Full status and characterization of exoplanets in regions located 0.5—10 AU from Host Stars (the regions at and behind the Snow Line) • Status of exoplanets around wide range of types of Host Stars • Discovery of low mass planets from the ground

  39. Second Generation Planetary Microlensing Survey • Survey and Follow-up in one • Network of 1—2-m class telescopes over the globe with large field (>1 square degs) cameras • Monitoring of the most microlensing efficient parts of the Galactic bulge with the cadence of ~15 minutes • No missing planets, easier estimation of survey statistics • Estimations: A network of three 1.3—2 m telescopes: the detection of 1—4 Earth mass planets, 10—15 super-Earths, 100 Jupiter mass planets per year • Five year long survey should provide resonable large sample of planets for estimation of the census of exoplanets down to Earth mass at orbits of 0.5—10 AU

  40. OGLE-IV: 2010 – …. • 32 chip 256 Mpixel mosaic CCD camera (+ 2 chips for guiding) • 2048 x 4102 pixel E2V 44-82 DD CCD detectors (15 mm). • 1.4 square degrees field, 0.26”/pixel • 20 sec. reading time • First light September 7, 2009 • Regular observations since March 4/5, 2010

  41. OGLE-IV Nowa Kamera Mozaikowa

  42. OGLE-IV 2012 BLG SKY Cadence: red – up to 30 epochs/night yellow – up to 10 epochs/night green – up to 3 epochs/night blue – ~1 epoch/night cyan – ~1 epoch /2 nights

  43. Real Time Microlensing: OGLE-IV • 58 O-IV fields analyzed in real time including all very high and high cadence • Statistics for 2012 BLG season: ~1700 on-line detections (~20 in O-I, ~60/season in O-II, ~600/season in O-III) • Total number of OGLE-IV microlensing fields: 107 – they will be gradually included to EWS

  44. OGLE-IV planetary microlenses 2010Commissioning Mode MOA-2010-BLG-117 MOA-2010-BLG-328 MOA-2010-BLG-477 MOA-2010-BLG-523

  45. 2012 Planetary Microlensing

  46. Free-Floating Planets • Microlensing event characteristic time: tE=RE/vtr • RE~sqrt(Mlens) → tE~sqrt(Mlens) • tE< 2 days – lensing object has planetary mass • High cadence observations needed for detection : (OGLE-IV: 18-60 min.) • MOA and OGLE data from 2006-2007: 10 short-lived microlensing events of likely planetary mass. No trace of host stars: population of unbound (FFP) or very distant exoplanets. • OGLE-IV data much better suited : preliminary estimation – 2011 season: ~40 events with tE< 2 days (shortest corespond statistically to a few Earth mass objects) • Origin: gravitational interactions – stellar encounters, ejection of planets during planetary system formation

  47. OGLE-IV 2013 BLG SKY Cadence: red – up to 30 epochs/night yellow – up to 10 epochs/night green – up to 3 epochs/night blue – ~1 epoch/night cyan – ~1 epoch /2 nights

  48. Prospects for Planetary Microlensing Field: Bright • New facilities: Bisdee Tier Tasmania, LCOGT Network, KMNet • Space Missions: WFIRST, EUCLID

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