Browsing by Author "Qian Q"

Now showing 1 - 3 of 3
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    KMT-2021-BLG-1547Lb: Giant microlensing planet detected through a signal deformed due to source binarity
    (EDP Sciences, France, 2023-10) Han C; Zang W; Jung YK; Bond IA; Chung S-J; Albrow MD; Gould A; Hwang K-H; Ryu Y-H; Shin I-G; Shvartzvald Y; Yang H; Yee JC; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge RW; Monard B; Qian Q; Liu Z; Maoz D; Penny MT; Zhu W; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hamada R; Hirao Y; Ishitani Silva S; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Matsubara Y; Miyazaki S; Muraki Y; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Tomoyoshi M; Tristram PJ; Vandorou A; Yama H; Yamashita K
    Aims. We investigate the previous microlensing data collected by the KMTNet survey in search of anomalous events for which no precise interpretations of the anomalies had been suggested. From this investigation, we find that the anomaly in the lensing light curve of the event KMT-2021-BLG-1547 is approximately described by a binary-lens (2L1S) model with a lens possessing a giant planet, but the model leaves unexplained residuals. Methods. We investigated the origin of the residuals by testing more sophisticated models that include either an extra lens component (3L1S model) or an extra source star (2L2S model) on top of the 2L1S configuration of the lens system. From these analyses, we find that the residuals from the 2L1S model originate from the existence of a faint companion to the source. The 2L2S solution substantially reduces the residuals and improves the model fit by δ x 2 = 67.1 with respect to the 2L1S solution. The 3L1S solution also improves the fit, but its fit is worse than that of the 2L2S solution by δ x 2 = 24.7. Results. According to the 2L2S solution, the lens of the event is a planetary system with planet and host masses (Mp/MJ, Mh/M·) = (1.47-0.77+0.64, 0.72-0.38+0.32) lying at a distance DL = 5.07-1.50+0.98 kpc, and the source is a binary composed of a subgiant primary of a late G or an early K spectral type and a main-sequence companion of a K spectral type. The event demonstrates the need for sophisticated modeling of unexplained anomalies if one wants to construct a complete microlensing planet sample.
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    Systematic reanalysis of KMTNet microlensing events, paper I: Updates of the photometry pipeline and a new planet candidate
    (Oxford University Press on behalf of the Royal Astronomical Society., 2024-02-01) Yang H; Yee JC; Hwang K-H; Qian Q; Bond IA; Gould A; Hu Z; Zhang J; Mao S; Zhu W; Albrow MD; Chung S-J; Kim S-L; Park B-G; Han C; Jung YK; Ryu Y-H; Shin I-G; Shvartzvald Y; Cha S-M; Kim D-J; Kim H-W; Lee C-U; Lee D-J; Lee Y; Pogge RW; Zang W; Abe F; Barry R; Bennett DP; Bhattacharya A; Donachie M; Fujii H; Fukui A; Hirao Y; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Silva SI; Li MCA; Matsubara Y; Muraki Y; Suzuki D; Tristram PJ; Yonehara A; Ranc C; Miyazaki S; Olmschenk G; Rattenbury NJ; Satoh Y; Shoji H; Sumi T; Tanaka Y; Yamawaki T
    In this work, we update and develop algorithms for KMTNet tender-love care (TLC) photometry in order to create a new, mostly automated, TLC pipeline. We then start a project to systematically apply the new TLC pipeline to the historic KMTNet microlensing events, and search for buried planetary signals. We report the discovery of such a planet candidate in the microlensing event MOA-2019-BLG-421/KMT-2019-BLG-2991. The anomalous signal can be explained by either a planet around the lens star or the orbital motion of the source star. For the planetary interpretation, despite many degenerate solutions, the planet is most likely to be a Jovian planet orbiting an M or K dwarf, which is a typical microlensing planet. The discovery proves that the project can indeed increase the sensitivity of historic events and find previously undiscovered signals.
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    Systematic Reanalysis of KMTNet Microlensing Events. II. Two New Planets in Giant-source Events
    (IOP Publishing on behalf of the American Astronomical Society., 2025-06-01) Yang H; Yee JC; Zhang J; Lee C-U; Kim D-J; Bond IA; Udalski A; Hwang K-H; Zang W; Qian Q; Gould A; Mao S; Albrow MD; Chung S-J; Han C; Jung YK; Ryu Y-H; Shin I-G; Shvartzvald Y; Cha S-M; Kim H-W; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Abe F; Bando K; Bennett DP; Bhattacharya A; Fukui A; Hamada R; Hamada S; Hamasaki N; Hirao Y; Silva SI; Itow Y; Koshimoto N; Matsubara Y; Miyazaki S; Muraki Y; Nagai T; Nunota K; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Terry SK; Tristram PJ; Vandorou A; Yama H; Mróz P; Skowron J; Poleski R; Szymański MK; Soszyński I; Pietrukowicz P; Kozłowski S; Ulaczyk K; Rybicki KA; Iwanek P; Wrona M
    In this work, we continue to apply the updated KMTNet tender-love care photometric pipeline to historical microlensing events. We apply the pipeline to a subsample of events from the KMTNet database, which we refer to as the giant source sample. Leveraging the improved photometric data, we conduct a systematic search for anomalies within this sample. The search successfully uncovers four new planet-like anomalies and recovers two previously known planetary signals. After detailed analysis, two of the newly discovered anomalies are confirmed as clear planets: KMT-2019-BLG-0578 and KMT-2021-BLG-0736. Their planet-to-host mass ratios are q ∼ 4 × 10−3 and q ∼ 1 × 10−4, respectively. Another event, OGLE-2018-BLG-0421 (KMT-2018-BLG-0831), remains ambiguous. Both a stellar companion and a giant planet in the lens system could potentially explain the observed anomaly. The anomaly signal of the last event, MOA-2022-BLG-038 (KMT-2022-BLG-2342), is attributed to an extra source star. Within this sample, our procedure doubles the number of confirmed planets, demonstrating a significant enhancement in the survey sensitivity.