The frequency of snowline-region planets from four-years of OGLE-MOA-Wise second-generation microlensing
| Autor: | Shvartzvald, Y., Maoz, D., Udalski, A., Sumi, T., Friedmann, M., Kaspi, S., Poleski, R., Szymański, M. K., Skowron, J., Kozłowski, S., Wyrzykowski, Ł., Mróz, P., Pietrukowicz, P., Pietrzyński, G., Soszyński, I., Ulaczyk, K., Abe, F., Barry, R. K., Bennett, D. P., Bhattacharya, A., Bond, I. A., Freeman, M., Inayama, K., Itow, Y., Koshimoto, N., Ling, C. H., Masuda, K., Fukui, A., Matsubara, Y., Muraki, Y., Ohnishi, K., Rattenbury, N. J., Saito, To., Sullivan, D. J., Suzuki, D., Tristram, P. J., Wakiyama, Y., Yonehara, A. |
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| Rok vydání: | 2015 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnras/stw191 |
| Popis: | 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 deg$^2$ 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 $\sim$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 $55^{+34}_{-22}\%$ of microlensed stars host a snowline planet. Moreover, we find that Neptunes-mass planets are $\sim10$ times more common than Jupiter-mass planets. The companion-to-host mass ratio distribution shows a deficit at $q\sim10^{-2}$, 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. Comment: 24 pages, 13 figures, 2 tables. 2016, MNRAS, 457, 4089 |
| Databáze: | arXiv |
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