KMT-2019-BLG-0371 and the Limits of Bayesian Analysis

Kim, Yun Hak; Chung, Sun-Ju; Yee, Jennifer C.; Udalski, A.; Bond, Ian A.; Jung, Youn Kil; Gould, Andrew; Albrow, Michael D.; Han, Cheongho; Hwang, Kyu-Ha; Ryu, Yoon-Hyun; Shin, In-gu; Shvartzvald, Yossi; Zang, Weicheng; Cha, Sang-Mok; Kim, Dong-Jin; Kim, Hyoun-Woo; Kim, Seung-Lee; Lee, Chung-Uk; Lee, Dong-Joo; Lee, Yongseok; Park, Byeong-Gon; Pogge, Richard W.; Poleski, Radek; Mróz, Przemek; Skowron, Jan; Szymański, Michal K.; Pietrukowicz, Pawel; Kozłowski, Szymon; Ulaczyk, Krzysztof; Rybicki, Krzysztof A.; Iwanek, Patryk; Wrona, Marcin; Gromadzki, Mariusz; Abe, Fumio; Barry, Richard; Bennett, David P.; Bhattacharya, Aparna; Donachie, Martin; Fujii, Hirosane; Itow, Yoshitaka; Hirao, Yuki; Kirikawa, Rintaro; Kondo, Iona; Koshimoto, Naoki; Matsubara, Yutaka; Muraki, Yasushi; Miyazaki, Shota; Ranc, Clément; Rattenbury, Nicholas J.; Satoh, Yuki; Shoji, Hikaru; Suzuki, Daisuke; Tristram, Paul J.; Tanaka, Yuzuru; Yamawaki, Tsubasa; Yonehara, Atsunori

doi:10.48550/arxiv.2101.12206

Cited by 3 publications

(4 citation statements)

References 21 publications

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“…In particular, if we remove the π E term from Equation ( 16), then the Bayesian host mass estimate is shifted lower to M host = 0.52 +0.32 −0.30 M . We also note that this is in good agreement with the general prediction of Kim et al (2021), for the case of θ E = 0.37 mas and µ rel < 10 mas yr −1 (and no other information), i.e., M host = 0.45 +0.30 −0.23 M . See their Figures 6 and 7.…”

Section: Bayesian Analysissupporting

confidence: 90%

Systematic KMTNet Planetary Anomaly Search, Paper I: OGLE-2019-BLG-1053Lb, A Buried Terrestrial Planet

Zang,

Hwang,

Udalski

et al. 2021

Preprint

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In order to exhume the buried signatures of "missing planetary caustics" in the KMTNet data, we conducted a systematic anomaly search to the residuals from point-source point-lens fits, based on a modified version of the KMTNet EventFinder algorithm. This search reveals the lowest mass-ratio planetary caustic to date in the microlensing event OGLE-2019-BLG-1053, for which the planetary signal had not been noticed before. The planetary system has a planet-host mass ratio of q = (1.25±0.13)×10 −5 . A Bayesian analysis yields estimates of the mass of the host star, M host = 0.61 +0.29 −0.24 M , the mass of its planet, M planet = 2.48 +1.19 −0.98 M ⊕ , the projected planet-host separation, a ⊥ = 3.4 +0.5 −0.5 au, and the lens distance of D L = 6.8 +0.6 −0.9 kpc. The discovery of this very low mass-ratio planet illustrates the utility of our method and opens a new window for a large and homogeneous sample to study the microlensing planet-host mass-ratio function down to q ∼ 10 −5 .

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Section: Bayesian Analysissupporting

confidence: 90%

Systematic KMTNet Planetary Anomaly Search, Paper I: OGLE-2019-BLG-1053Lb, A Buried Terrestrial Planet

Zang,

Hwang,

Udalski

et al. 2021

Preprint

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“…The estimated host and planet masses are (M 1 , M 2 ) ∼ (0.65 M ⊙ , 2 M J ) for KMT-2018-BLG-1976L, ∼ (0.69 M ⊙ , 1 M J ) for KMT-2018-BLG-1996L, and ∼ (0.80 M ⊙ , 14 M J ) for OGLE-2019-BLG-0954L. The estimated mass of OGLE-2019-BLG-0954L is in a good agreement with the θ E -M relation presented in Figure 7 of Kim et al (2021). According to the estimated masses, the hosts of planets are commonly K-type main-sequence stars.…”

Section: Physical Lens Parameterssupporting

confidence: 84%

Three microlensing planets with no caustic-crossing features

Han,

Udalski,

Kim

et al. 2021

Preprint

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Aims. We search for microlensing planets with signals exhibiting no caustic-crossing features, considering the possibility that such signals may be missed due to their weak and featureless nature. Methods. For this purpose, we reexamine the lensing events found by the KMTNet survey before the 2019 season. From this investigation, we find two new planetary lensing events, KMT-2018-BLG-1976 and KMT-2018-BLG-1996. We also present the analysis of the planetary event OGLE-2019-BLG-0954, for which the planetary signal was known, but no detailed analysis has been presented before. We identify the genuineness of the planetary signals by checking various interpretations that can generate short-term anomalies in lensing light curves. Results. From Bayesian analyses conducted with the constraint from available observables, we find that the host and planet masses are (M 1 , M 2 ) ∼ (0.65 M ⊙ , 2 M J ) for KMT-2018-BLG-1976L, ∼ (0.69 M ⊙ , 1 M J ) for KMT-2018-BLG-1996L, and ∼ (0.80 M ⊙ , 14 M J ) for OGLE-2019-BLG-0954L. The estimated distance to OGLE-2019-BLG-0954L, 3.63 +1.22 −1.64 kpc, indicates that it is located in the disk, and the brightness expected from the mass and distance matches well the brightness of the blend, indicating that the lens accounts for most of the blended flux. The lens of OGLE-2019-BLG-0954 could be resolved from the source by conducting high-resolution follow-up observations in and after 2024.

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“…If we adopt a snow-line scaling a snow = 2.7AU(M host /M ⊙ ), then the planets projected separation is a ⊥ ∼ 4 a snow . Kim et al (2021) have shown that, unless µ rel > 10 mas yr −1 (or there is additional information such as a microlens parallax measurement), the Bayesian mass estimate depends only on θ E . While this condition does not apply to KMT-2016-BLG-2605, if we nevertheless input θ E = 0.116 mas into their Figures 7, we obtain M = 0.08 +0.06 −0.04 M ⊙ .…”

Section: Physical Parametersmentioning

confidence: 99%

“…To this sample, we add KMT-BLG-2019-BLG-0371 (Kim et al 2021), which is not listed at NASA Exoplanet Archive because it has not yet been accepted for publication.…”

Section: Ensemble Of Short-timescale Planetsmentioning

confidence: 99%

Shortest Microlensing Event with a Bound Planet: KMT-2016-BLG-2605

Ryu,

Hwang,

Gould

et al. 2021

Preprint

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KMT-2016-BLG-2605, with planet-host mass ratio q = 0.012 ± 0.001, has the shortest Einstein timescale, t E = 3.41 ± 0.13 days, of any planetary microlensing event to date. This prompts us to examine the full sample of 7 short (t E < 7 day) planetary events with good q measurements. We find that six have clustered Einstein radii θ E = 115 ± 20 µas and lens-source relative proper motions µ rel ≃ 9.5 ± 2.5 mas yr −1 . For the seventh, these two quantities could not be measured. These distributions are consistent with a Galactic-bulge population of very low-mass (VLM) hosts near the hydrogen-burning limit. This conjecture could be verified by imaging at first adaptive-optics light on next-generation (30m) telescopes. Based on a preliminary assessment of the sample, "planetary" companions (i.e., below the deuterium-burning limit) are divided into "genuine planets", formed in their disks by core accretion, and very low-mass brown dwarfs, which form like stars. We discuss techniques for expanding the sample, which include taking account of the peculiar "anomaly dominated" morphology of the KMT-2016-BLG-2605 light curve.

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KMT-2019-BLG-0371 and the Limits of Bayesian Analysis

Cited by 3 publications

References 21 publications

Systematic KMTNet Planetary Anomaly Search, Paper I: OGLE-2019-BLG-1053Lb, A Buried Terrestrial Planet

Systematic KMTNet Planetary Anomaly Search, Paper I: OGLE-2019-BLG-1053Lb, A Buried Terrestrial Planet

Three microlensing planets with no caustic-crossing features

Shortest Microlensing Event with a Bound Planet: KMT-2016-BLG-2605

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