OGLE-2003-BLG-235/MOA-2003-BLG-53: A Definitive Planetary Microlensing Event David Bennett University of Notre Dame

Author List: I.A. Bond, A. Udalski, M. Jaroszynski, N.J. Rattenbury, B. Paczynski, I. Soszynski, L. Wyrzykowski, M.K. Szymanski, M. Kubiak, O. Szewczyk, K. Zebrun, G. Pietrzynski, F.Abe, D.P. Bennett, S. Eguchi, Y. Furuta, J.B. Hearnshaw, K. Kamiya, P.M. Kilmartin, Y. Kurata, K. Masuda, Y. Matsubara, Y. Muraki, S. Noda, K. Okajima, T. Sako, T. Sekiguchi, D.J. Sullivan, T. Sumi, P.J. Tristram, T. Yanagisawa, and P.C.M. Yock (the MOA and OGLE collaborations)

Real-Time Lightcurve Monitoring is Critical! Ian Bond (IFA, Edinburgh) noticed a caustic crossing for this event on July 23, He contacted the telescope and requested additional images The requested images caught the caustic crossing endpoint. This caustic endpoint data is critical to the conclusion that a planet is required.

Lightcurve OGLE alert

Definition of a Planet Formed by core accretion? (with a rocky core) –But we don’t know that this is how planets form! –We aren’t even sure about Jupiter’s rocky core! Secondary Mass < 13 M jupiter ? –This is the Deuterium burning threshold for solar metalicity, but why is that important? –What if binary is a 0.08 M  ? Mass ratio may only be 0.16! –In the brown dwarf desert Planetary mass fraction  < 0.03 –In the brown dwarf desert –Easily measured in a microlensing lightcurve!!

Lightcurve close-up & fit Cyan curve is the best fit single lens model –  2 = 651 Magenta curve is the best fit model w/ mass fraction   0.03 –  2 = days inside caustic = 0.12 t E –Long for a planet, –but  mag = only 20-25% –as expected for a planet near the Einstein Ring

Caustic Structure & Magnification Pattern Blue and red dots indicate times of observations Parameters: t E = 61.6  1.8 days t 0 =  0.13 MJD u min =  a p =   =  q =  /(1+  )  =   1.4  t * =  days or  * /  E = 

Alternative Models: a p < 1  2 = t E = 75.3 days t 0 = MJD u min = a p =  =  = -6.1  t * = days Also planetary!

Alternative Models: a p < 1  2 = t E = 75.3 days t 0 = MJD u min = a p =  =  = -6.1  t * = days Also planetary!

Alternative Models:  ~ 180   2 = t E = 76.0 days t 0 = MJD u min = a p =  =  =  t * = days Also planetary!

Alternative Models:  ~ 180   2 = t E = 76.0 days t 0 = MJD u min = a p =  =  =  t * = days Also planetary!

Alternative Models: Early 1 st Caustic Crossing  2 = 7.37 t E = 58.5 days t 0 = MJD u min = a p =  =  =  t * = days Excluded by 2.7  Adjust  =  to  =  0.011

Lens Star Constraints Using I source = 19.7 and V-I = 1.58,we conclude that the source is a bulge G dwarf of radius:  * = 520  80  as I blend = 20.7  0.4 Gives likelihood curve

Planetary Parameters in Physical Units Best fit lens distance = 5.2 kpc –90% c.l. range is kpc Best fit separation = 3.0 AU –90% c.l. range is AU Best fit stellar mass = 0.36 M  –90% c.l. range is M  Best fit planet mass = 1.5 M jup –90% c.l. range is M jup If lens star is a 0.6 M  white dwarf –D lens = 6.1 kpc –a p = 1.8 AU –M p = 2.5 M jup

Conclusions 1 st definitive  lensing planetary discovery - complete coverage not required for characterization Real-time data monitoring was critical! S. Gaudi video