The frequency of snowline-region planets from four-years of OGLE-MOA-Wise second-generation microlensing

Y Shvartzvald; D Maoz; A Udalski; T Sumi; M Friedmann; S Kaspi; R Poleski; M K Szymański; J Skowron; S Kozłowski; L Wyrzykowski; P Mróz; P Pietrukowicz; G Pietrzyński; I Soszyński; K Ulaczyk; F Abe; R K Barry; D P Bennett; A Bhattacharya; I A Bond; M Freeman; K Inayama; Y Itow; N Koshimoto; C H Ling; K Masuda; A Fukui; Y Matsubara; Y Muraki; K Ohnishi; N J Rattenbury; To Saito; D J Sullivan; D Suzuki; P J Tristram; Y Wakiyama; A Yonehara

doi:10.1093/mnras/stw191

The frequency of snowline-region planets from four-years of OGLE-MOA-Wise second-generation microlensing

Mon Not R Astron Soc. 2016 Apr 21;457(4):4089-4113. doi: 10.1093/mnras/stw191. Epub 2016 Feb 27.

Authors

Y Shvartzvald^{1

2}, D Maoz^{1

2}, A Udalski^{3

4}, T Sumi^{5

6}, M Friedmann^{1

2}, S Kaspi^{1

2}, R Poleski^{7

4}, M K Szymański^{3

4}, J Skowron^{3

4}, S Kozłowski^{3

4}, L Wyrzykowski^{3

4}, P Mróz^{3

4}, P Pietrukowicz^{3

4}, G Pietrzyński^{3

4}, I Soszyński^{3

4}, K Ulaczyk^{8

4}, F Abe^{9

6}, R K Barry^{10

6}, D P Bennett^{11

6}, A Bhattacharya^{11

6}, I A Bond^{12

6}, M Freeman^{13

6}, K Inayama^{14

6}, Y Itow^{9

6}, N Koshimoto^{5

6}, C H Ling^{12

6}, K Masuda^{9

6}, A Fukui^{15

6}, Y Matsubara^{9

6}, Y Muraki^{9

6}, K Ohnishi^{16

6}, N J Rattenbury^{13

6}, To Saito^{17

6}, D J Sullivan^{18

6}, D Suzuki^{11

6}, P J Tristram^{19

6}, Y Wakiyama^{9

6}, A Yonehara^{14

6}

Affiliations

¹ School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel.
² The Wise Observatory Group.
³ Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland.
⁴ Optical Gravitational Lens Experiment (OGLE) Collaboration.
⁵ Department of Earth and Space Science, Osaka University, Osaka 560-0043, Japan.
⁶ Microlensing Observations in Astrophysics (MOA) Collaboration.
⁷ Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USA.
⁸ Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
⁹ Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan.
¹⁰ Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
¹¹ University of Notre Dame, Department of Physics, 225 Nieuwland Science Hall, Notre Dame, IN 46556-5670, USA.
¹² Institute of Information and Mathematical Sciences, Massey University, Private Bag 102-904, North Shore Mail Centre, Auckland, New Zealand.
¹³ Department of Physics, University of Auckland, Private Bag 92-019, Auckland 1001, New Zealand.
¹⁴ Department of Physics, Faculty of Science, Kyoto Sangyo University, 603-8555 Kyoto, Japan.
¹⁵ Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asakuchi, Okayama 719-0232, Japan.
¹⁶ Nagano National College of Technology, Nagano 381-8550, Japan.
¹⁷ Tokyo Metropolitan College of Aeronautics, Tokyo 116-8523, Japan.
¹⁸ School of Chemical and Physical Sciences, Victoria University, Wellington, New Zealand.
¹⁹ Mt. John University Observatory, P.O. Box 56, Lake Tekapo 8770, New Zealand.

Abstract

We present a statistical analysis of the first four seasons from a "second-generation" microlensing survey for extrasolar planets, consisting of near-continuous time coverage of 8 deg² of the Galactic bulge by the OGLE, MOA, and Wise microlensing surveys. During this period, 224 microlensing events were observed by all three groups. Over 12% of the events showed a deviation from single-lens microlensing, and for ~1/3 of those the anomaly is likely caused by a planetary companion. For each of the 224 events we have performed numerical ray-tracing simulations to calculate the detection efficiency of possible companions as a function of companion-to-host mass ratio and separation. Accounting for the detection efficiency, we find that $55_{- 22}^{+ 34} %$ of microlensed stars host a snowline planet. Moreover, we find that Neptunes-mass planets are ~ 10 times more common than Jupiter-mass planets. The companion-to-host mass ratio distribution shows a deficit at q ~ 10^-2, separating the distribution into two companion populations, analogous to the stellar-companion and planet populations, seen in radial-velocity surveys around solar-like stars. Our survey, however, which probes mainly lower-mass stars, suggests a minimum in the distribution in the super-Jupiter mass range, and a relatively high occurrence of brown-dwarf companions.

Keywords: Galaxy: stellar content; binaries: general; gravitational lensing: micro; planetary systems; surveys.

Grants and funding

SCMD-PlanetaryScience/Science Planetary Science NASA/United States