Deep mmt transit survey of the open cluster m37 IV: Limit on the fraction of stars with planets as small as 0.3rj

We present the results of a deep (15 r 23), 20 night survey for transiting planets in the intermediate-age open cluster M37 (NGC 2099) using the Megacam wide-field mosaic CCD camera on the 6.5 m MMT.We do not detect any transiting planets among the ?1450 observed cluster members. We do, however, identify a ?1RJ candidate planet transiting a ?0.8 M Galactic field star with a period of 0.77 days. The source is faint (V = 19.85 mag) and has an expected velocity semiamplitude of K?220 m s?1 (M/MJ ). We conduct Monte Carlo transit injection and recovery simulations to calculate the 95% confidence upper limit on the fraction of cluster members and field stars with planets as a function of planetary radius and orbital period. Assuming a uniform logarithmic distribution in the orbital period, we find that <1.1%, <2.7%, and <8.3% of cluster members have 1.0RJ planets within extremely hot Jupiter (EHJ; 0.4 < P < 1.0 day), very hot Jupiter (VHJ; 1.0 < P < 3.0 day), and hot Jupiter (HJ; 3.0 < P < 5.0 day) period ranges, respectively. For 0.5RJ planets, the limits are less than 3.2% and less than 21% for EHJ and VHJ period ranges, respectively, while for 0.35RJ planets we can only place an upper limit of less than 25% on the EHJ period range. For a sample of 7814 Galactic field stars, consisting primarily of FGKM dwarfs, we place 95% upper limits of <0.3%, <0.8%, and <2.7% on the fraction of stars with a 1.0RJ EHJ, VHJ, and HJ, respectively, assuming that the candidate planet is not genuine. If the candidate is genuine the frequency of ?1.0RJ planets in the EHJ period range is 0.002%<fEHJ < 0.5% with 95% confidence. We place limits of <1.4%, <8.8%, and <47% for 0.5RJ planets, and a limit of <16% on 0.3RJ planets in the EHJ period range. This is the first transit survey to place limits on the fraction of stars with planets as small as Neptune.