Download Microlensing

Microlensing, « blue dot team »
Jean-Philippe Beaulieu
Collaborators/interested by a microlensing program on EUCLID
IAP : Batista, Marquette
Observatoire Toulouse : Fouqué
Manchester : Kerins, Mao, Rattenbury
Heidelberg : Cassan, Grebel
ESO : Kubas
USA : Bennett, Gaudi, Gould
BLUE DOT LOGO ????
Action item list for microlensers in 2008
Useful action already done :
White paper to exoplanet task force (Bennett et al. astroph)
JDEM RFI answer (Bennett, et al., )
Participation to exoplanet forum (Gaudi et al.)
Exoplanet task force report
EPRAT white paper (Beaulieu et al.)
Another EPRAT white paper (Dominik et al.)
Being done now :
Celebrating a 3 earth mass planet
Discovering more planets in 2008
Next generation of ground based survey
Discussing a microlensing program on board EUCLID
To be done shortly :
Organisation of a microlensing workshop in Paris (January 2009)
Reading the Scriptures (aka exoplanet task force) :
“Recommendation B. II. 2 Without impacting the launch
schedule of the astrometric mission cited above*,
launch a Discovery-class space-based microlensing
mission to determine the statistics of planetary mass
and the separation of planets from their host stars as
a function of stellar type and location in the galaxy,
and to derive  over a very large sample.
* “Recommendation B. I. a. 1 Launch and operate a space based
astrometric mission capable of detecting planets down to the
mass of the Earth around 60-100 nearby stars…”
Technology
• Ground-based 1-2m, Wide FOV Telescope
– Several very similar telescopes already operating
• MOA-II
• Pan-STARRS-1 - $20M
• Space-based microlensing mission
– Requires almost no technology development.
– Can extensively leverage other missions (Spitzer, NextView,
Ikonos, JWST)
– Can use many components that are demonstrated on orbit or
flight qualified.
MPF Mission Design
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•
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•
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1.1-m aperture consisting of a threemirror anastigmat telescope feeding
a 147 Mpixel HgCdTe focal plane (35
20482 arrays)
The spacecraft bus is a near-identical
copy of that used for Spitzer.
The telescope system very similar to
NextView commercial Earthobserving telescope designs.
Detectors developed for JWST meet
MPFs requirements.
All elements are at TRL 6 or better.
Total Cost $300M (without launch
vehicle)
Property
Value
Units
Launch Vehicle
7920-9.5
Delta II
Orbit
Inclined GEO 28.7
degrees
Mission Lifetime
4.0
years
Telescope Aperture
1.1
meters (diam.)
Field of View
0.95x0.68
degrees
Spatial Resolution
0.240
arcsec/pixel
Pointing Stability
0.048
arcsec
Focal Plane Format
145
Megapixels
Spectral Range
600-1700
nm in 3 bands
Quantum Efficiency
>75%
>55%
900-1400 nm
700-1600 nm
Dark Current
<1
e-/pixel/sec
Readout Noise
<30
e-/read
Photometric
Accuracy
Data Rate
1% or better
at J=20.5
50.1
Mbits/sec
Table 1: Key Space Mission R equi rements
MPF Mission Requirements
Dark Energy Synergy
• Space-based microlensing mission telescope requirements are very
similar to the requirements for many proposed dark energy missions.
• Combined dark energy/planet finding mission probably could be
accomplished at a substantial savings.
• ADEPT, Destiny, SNAP, DUNE/SPACE/Euclid
– Wide FOV, >1.1m aperture, technical specifications appear to satisfy spacebased microlensing survey specifications
– DUNE/SPACE/Euclid can meet all the science goals without modification to
hardware.
• Trade study:
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–
–
–
–
–
–
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Observing time
Pass bands
FOV and Detectors
Orbit
Telemetry
Aperture
Optics
Pointing
Dark Energy Synergy
Everything that is good for COSMIC SHEAR measurements,
is good for microlensing.
We have the same requirements, just slightly less stringent.
Everything that is good for COSMIC SHEAR measurements,
is good for microlensing.
Everything that is good for COSMIC SHEAR measurements,
is good for microlensing.
Everything that is good for COSMIC SHEAR measurements,
is good for microlensing.
Everything that is good for COSMIC SHEAR measurements,
is good for microlensing.
Summary
•
Ground-based Next-Generation Survey:
+$10M—$20M
– Complete network with a single wide FOV 1-2m telescope in SA.
– Frequency of planets >M beyond the snow line.
– Test planet formation theories.
•
Either: Space-based Microlensing Mission: +$300M + launch
– Complete census of planets with mass greater than Mars and a > 0.5 AU.
– Sensitivity to all Solar System planet analogs except Mercury.
– Demographics of planetary systems - tests planet formation theories.
– Detect “outer” habitable zone (Mars-like orbits) where detection by imaging is
easiest.
– Can find moons and free floating planets.
•
•
Or: Joint lensing/Dark Energy Mission
+$100M—$200M?
Total cost to “Exoplanet Community”: $120M—$420M
The near-term: automated follow-up
1-5 yr
Milestones:
A. An optimised planetary microlens follow-up
network, including feedback from fully-automated
real-time modelling.
B. The first census of the cold planet population,
involving planets of Neptune to super-Earth (few M⊕
to 20 M⊕) with host star separations around 2 AU.
C. Under highly favourable conditions, sensitivity to
planets close to Earth mass with host separations
around 2 AU.
Running existing facilities with existing operations
The medium-term: wide-field telescope
networks
5-10 yr
Milestones:
A. Complete census of the cold planet population
down to ~10 M⊕ with host separations above 1.5
AU.
B. The first census of the free-floating planet
population.
C. Sensitivity to planets close to Earth mass with host
separations around 2 AU.
Several existing nodes already.
Adding one node in South Africa, + operation : 10-20 M$
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
Searching for low mass extra solar
planets via microlensing.
Jean-Philippe Beaulieu, (PLANET/RoboNET, HOLMES)
Target Field in the Central Galactic Bulge
Galactic center
8 kpc
Sun
1-7 kpc from Sun
Light curve
Source star
and images
Probability ~10-6
Lens star
and planet
Observer
A planetary companion
tE  20 d, M  0.3 M sun :
tp  q tE
Jupiter : q  3 10-3  tp  1 d
Terre : q  105  tp  1.5 h
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.
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 community.
Cooperation is the way to go !
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.
2 Jupiter mass planets detected microlensing (2004, 2005) :
•Strong caustic
•Central caustic
Small fraction of M dwarfs orbited by a Jovian companion
OGLE-2005-BLG-390
Coopération : PLANET/RoboNET, OGLE-III, MOA-II
PROBABILITY DENSITIES OF THE STAR
AND ITS PLANET
OGLE-2005-BLG-169Lb : a weak Neptune planet signal
Gould et al. 2006, MicroFUN, OGLE, RoboNet
Gaudi et al., 2008, Science
• 3 bodies, 0.5 Mo, ~0.7 Mjup, ~0.3 Mjup
• Triple lens, with finite source effects, parallaxe,
& taking into account rotation of planets
• Ultimate nightmare for normal microlensing planet hunters.
• Two other multiple systems « in stock », modeling underway.
• One has been giving headaches to Bennett since late 2004.
• The other one is much further down the road… (Dong et al. 2008)
Earth at 1 AU ?
Earth mass
planet signal is
washed out for
giant source stars
DUNE-ML photometry
DUNE MICROLENSING PLANET SEARCH
Monitor 2 108 stars down to J,Y,H ~22
Color information ~ once a week
~4 deg2 observed every ~20 min
Sensitivity to planets with a 3 months dedicated observing
program :
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16 frocky rocky planets (Earth, Venus, Mars)
580 fjupiter Jupiter planets
120 fsat Saturne
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
CURRENT RESULTS
Microlensing is probing “Frozen” planets.
7 microlensing planets for 3 scenarios :
• 3 Strong caustic
• 2 High mag central caustic
• 1 Planetary caustic
3 ~Jupiters, 1 ~5.5 Earth, 1 ~13 Earth
(Probability of detecting Jupiters is ~30 times larger)
Giant planets are rare, suggests 1-15 MEARTH might be common
1 system with ~0.7 Jup (2.3 AU), and ~0.3 Jup (4.6 AU)
Several planets in “stock”… modeling underway.
Indication : systems with multiple planets more common ?
~Earth mass planets on ~AU orbits to be discovered soon…
Total cooperation between teams 
CONTRIBUTION WITHIN BDT
Frozen super Earth - Earth mass planets are already accessible
Multiple planet systems with frozen ~Earth and Giant planet are accessible
Statistics about such systems in a few years
Down to frozen mars mass planet :
•Monitoring very high mag events with small telescopes
•Network of wide field imagers
•Wide field imager in space
Habitable earth :
•Wide field imager in space (recomm from exo planet task force)