Keck Key Strategic Mission Support Program for WFIRST

Transcription

1 Keck Key Strategic Mission Support Program for WFIRST David Bennett January 26, 2018 NASA Goddard Space Flight Center 1

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3 Why complete the census? A complete census is needed to understand planet formation and evolution. Most giant planets likely formed beyond the snow line. Place our solar system in context. Water for habitable planets likely delivered from beyond the snow line. Understand the frequency of planet formation in different environments. Kepler s final estimate of η Earth is likely to have a substantial uncertainty. The basics of planet formation cannot be understood without observational data! 3

4 Current Results vs. Population Synthesis MOA Exoplanet Mass Ratio Function reveals a fundamental core accretion theory flaw! No sub-saturn mass gap is observed beyond the snow line Predicted by run-away gas accretion process that is thought to form gas giants Is gas giant formation be more complicated than the simple accretion of H/He onto a core? Could sub-saturn gap appear in the exoplanet mass function, but not the mass ratio function? WFIRST should measure masses of most planets standard migration Factor of 25 discrepancy! no migration Turning off migration improves the cold planet distribution, but does not generate enough planets at q ~ , or about 50 M Å (Bern group results are similar) (Suzuki s talk!)

5 2 (of 3) Mass-Distance Relations source ص rel - finite source or follow-up Angular Einstein radius q E = µ rel t E µ rel = q * /t * q * = source star angular radius D L and D S are the lens and source distances source ØMicrolensing Parallax (Effect of Earth s orbital motion) Einstein radius projected to observer, OR ØOne of above M L = c 2 4G θ 2 D S D L E D S D L M L = c 2 r 4G 2 D S D L E D S D L Lens brightness & color(ao,hst) M mass-distance relationèd L = c 2 r L 4G E θ E r E lens q E lens r E Earth Earth 5

6 Any 2 of 3 Mass-Distance Relations Give Mass and Distance Ø Finite source effect or lens-source proper motion: Angular Einstein radius q E =q * t E /t * q * = source star angular radius D L and D S are the lens and source distances Ø Lens brightness from high resolution image used in Mass- Luminosity relation mass-distance relation è D L, M L source q E lens Earth M L = c 2 4G θ 2 D S D L E D S D L Ø Lens-source relative proper motion is key to lens star identification Ø Independent measurement in every passband Ground Space Ø Seeing limited image don t help

7 Bayesian Analysis for Excess Flux The lens star is usually blended with the source, but there can be companions to the lens and source or even ambient stars also blended with the source. Naoki Koshimoto et al. (2018)

8 Planetary Feature Confirmed OGLE-2005-BLG-169Lb µfun, OGLE, MOA & PLANET This feature plus fit source brightness and color yields lenssource relative proper motion (angular velocity), μ rel

9 Confirm Lens-Source Separation & Lens ID H-band AO 4.9 F814W& Lens& Source& F555W& 0.42 F438W& HST Lens& Source& Lens& Source& Bennett et al Keck result: Batista et al Aparna Bhattacharya see her talk! Virginie Batista HST images 6.5 yrs after event and Keck AO images 8.3 yrs after event confirm prediction M * = 0.69 ± 0.02M m p = 14.1± 0.9M a = 3.5 ± 0.3 AU a 3d = AU D L = 4.1± 0.4 kpc

10 4-Color BVIH + θ E Measurement of OGLE-2005-BLG-169 Host Mass Bennett et al Keck result: Batista et al M * = 0.69 ± 0.02M m p = 14.1± 0.9M a = 3.5 ± 0.3 AU a 3d = AU D L = 4.1± 0.4 kpc

11 Keck Key Strategic Mission Support Program NASA-KECK 2018A PROPOSAL #66 Development of the WFIRST Exoplanet Mass Measurement Method Principal Investigator: David Bennett NASA Goddard Spaceflight Center Code Greenbelt Road Greenbelt, MD Awarded 10 half-nights per year for 2 years Co-Investigators: Jean-Philippe Beaulieu, Institut Astrophysique de Paris, France Calen Henderson, IPAC, Caltech Jessica Lu, University of California, Berkeley Virginie Batista, Institut Astrophysique de Paris, France Aparna Bhattacharya, NASA Goddard Space Flight Center Daisuke Suzuki, Institute of Space and Astronautical Science, JAXA, Japan Takahiro Sumi, Osaka University, Japan Valerio Bozza, University of Salerno, Italy Ian Bond, Massey University, New Zealand Andrzej Udalski, Warsaw University Observatory, Poland Lukasz Wyrzykowsk, Warsaw University Observatory, Poland Marie Ygouf, IPAC, Caltech Naoki Koshimoto, Osaka University, Japan Clement Ranc, NASA Goddard Space Flight Center Yuki Hirao, NASA Goddard Space Flight Center B. Scott Gaudi, Ohio State University 11

12 Keck Key Strategic Mission Support Goals Measure or constrain masses and distances for ~60+ microlens host stars and planets Test core accretion with exoplanet mass function Resolve ambiguities with unresolved excess flux detections Develop the WFIRST method Measure over-constrained systems, including to determine uncertainties Are masses and distances poorly determined in high extinction fields? 12

13 Target Priorities vents are indicated by q 1 and q 2. Target RA DEC I-mag q 1, (q 2 ) r(mas) E. Calc. OGLE :05: :53: S OGLE :50: :40: C12 MOA-bin-1 17:51: :47: MR OGLE :52: :05: (14, 5.0) G10 OGLE :05: :52: MR MOA :08: :09: S16 MOA :09: :13: G10 OGLE :05: :25: S16 MOA :54: :46: S16 MOA :58: :11: S16 OGLE MOA :59: :06: :45:34-26:49: S16 S16 MOA :06: :27: S16 MOA :00: :14: S16 MOA :55: :10: S16 MOA :52: :02: S16 MOA :16: :31: MR 4 Planet hosts with large separation from hosts, other planet hosts, stellar binaries with mass measurements. Giants sources require very large separation. OGLE :55: :12: S MACHO :01: :49: OGLE :48: :57: MOA :55: :05: MR MOA :56: :52: MR MOA :01: :19: MR MOA :06: :25: MR MOA :01: :01: MR MOA :09: :18: MR MOA :02: :44: MR MOA :07: :56: MR 13

14 New, Old Planetary Events MOA-bin event MOA-bin-17 = OGLE-2006-BLG event Old events have larger separations allowing lens-source resolution. These are 2 of 6 new candidate planetary events from the MOA analysis. 14

15 Help Requested Modeling & Old Planets Most stellar binaries have only preliminary modeling We want stellar binary events with large lens-source separations and microlensing parallax signals Mains sequence or sub-giant source stars are preferred unless the lenssource separation is quite large We need to know all degenerate models prior to observations High magnifications event with faint sources are good targets, because lens and source may have similar brightness PLANET and!fun may have old unpublished binary events OGLE may have New, Old planetary events that could be good targets 15

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