Browsing by Author "Gould, Andrew"

Now showing 1 - 5 of 5
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    A distant sample of halo wide binaries from SDSS
    (2018) Coronado, Johanna; Paz Sepulveda, Maria; Gould, Andrew; Chaname, Julio
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    Four microlensing giant planets detected through signals produced by minor-image perturbations
    (2024) Han, Cheongho; Bond, Ian A.; Lee, Chung-Uk; Gould, Andrew; Albrow, Michael D.; Chung, Sun-Ju; Hwang, Kyu-Ha; Jung, Youn Kil; Ryu, Yoon-Hyun; Shvartzvald, Yossi; Shin, In-Gu; Yee, Jennifer C.; Yang, Hongjing; Zang, Weicheng; Cha, Sang-Mok; Kim, Doeon; Kim, Dong-Jin; Kim, Seung-Lee; Lee, Dong-Joo; Lee, Yongseok; Park, Byeong-Gon; Pogge, Richard W.; Abe, Fumio; Bando, Ken; Barry, Richard; Bennett, David P.; Bhattacharya, Aparna; Fujii, Hirosame; Fukui, Akihiko; Hamada, Ryusei; Hamada, Shunya; Hamasaki, Naoto; Hirao, Yuki; Ishitani Silva, Stela; Itow, Yoshitaka; Kirikawa, Rintaro; Koshimoto, Naoki; Matsubara, Yutaka; Miyazaki, Shota; Muraki, Yasushi; Nagai, Tutumi; Nunota, Kansuke; Olmschenk, Greg; Ranc, Clement; Rattenbury, Nicholas J.; Satoh, Yuki; Sumi, Takahiro; Suzuki, Daisuke; Tomoyoshi, Mio; Tristram, Paul J.; Vandorou, Aikaterini; Yama, Hibiki; Yamashita, Kansuke; Bachelet, Etienne; Rota, Paolo; Bozza, Valerio; Zielinski, Pawel; Street, Rachel A.; Tsapras, Yiannis; Hundertmark, Markus; Wambsganss, Joachim; Wyrzykowski, Lukasz; Figuera Jaimes, Roberto; Cassan, Arnaud; Dominik, Martin; Rybicki, Krzysztof A.; Rabus, Markus
    Aims. We investigated the nature of the anomalies appearing in four microlensing events KMT-2020-BLG-0757, KMT-2022-BLG-0732, KMT-2022-BLG-1787, and KMT-2022-BLG-1852. The light curves of these events commonly exhibit initial bumps followed by subsequent troughs that extend across a substantial portion of the light curves. Methods. We performed thorough modeling of the anomalies to elucidate their characteristics. Despite their prolonged durations, which differ from the usual brief anomalies observed in typical planetary events, our analysis revealed that each anomaly in these events originated from a planetary companion located within the Einstein ring of the primary star. It was found that the initial bump arouse when the source star crossed one of the planetary caustics, while the subsequent trough feature occurred as the source traversed the region of minor image perturbations lying between the pair of planetary caustics. Results. The estimated masses of the host and planet, their mass ratios, and the distance to the discovered planetary systems are (M-host/M-circle dot, M-planet/M-J, q/10(-3), D-L/kpc) = (0.58(-0.30)(+0.33), 10.71(-5.61)(+6.17), 17.61 +/- 2.25, 6.67(-1.30)(+0.93)) for KMT-2020-BLG-0757, (0.53(-0.31)(+0.31), 1.12(-0.65)(+0.65), 2.01 +/- 0.07, 6.66(-1.84)(+1.19)) for KMT-2022-BLG-0732, (0.42(-0.23)(+0.32), 6.64(-3.64)(+4.98), 15.07 +/- 0.86, 7.55(-1.30)(+0.89)) for KMT-2022-BLG-1787, and (0.32(-0.19)(+0.34), 4.98(-2.94)(+5.42), 8.74 +/- 0.49, 6.27(-1.15)(+0.90)) for KMT-2022-BLG-1852. These parameters indicate that all the planets are giants with masses exceeding the mass of Jupiter in our solar system and the hosts are low-mass stars with masses substantially less massive than the Sun.
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    Gaia22dkvLb: A Microlensing Planet Potentially Accessible to Radial-velocity Characterization
    (2024) Wu, Zexuan; Dong, Subo; Yi, Tuan; Liu, Zhuokai; El-Badry, Kareem; Gould, Andrew; Wyrzykowski, L.; Rybicki, K. A.; Bachelet, Etienne; Christie, Grant W.; de Almeida, L.; Monard, L. A. G.; McCormick, J.; Natusch, Tim; Zielinski, P.; Chen, Huiling; Huang, Yang; Liu, Chang; Merand, A.; Mroz, Przemek; Shangguan, Jinyi; Udalski, Andrzej; Woillez, J.; Zhang, Huawei; Hambsch, Franz-Josef; Mikolajczyk, P. J.; Gromadzki, M.; Ratajczak, M.; Kruszynska, Katarzyna; Ihanec, N.; Pylypenko, Uliana; Sitek, M.; Howil, K.; Zola, Staszek; Michniewicz, Olga; Zejmo, Michal; Lewis, Fraser; Bronikowski, Mateusz; Potter, Stephen; Andrzejewski, Jan; Merc, Jaroslav; Street, Rachel; Fukui, Akihiko; Jaimes, R. Figuera; Bozza, V.; Rota, P.; Cassan, A.; Dominik, M.; Tsapras, Y.; Hundertmark, M.; Wambsganss, J.; Bakowska, K.; Slowikowska, A.
    We report discovering an exoplanet from following up a microlensing event alerted by Gaia. The event Gaia22dkv is toward a disk source rather than the traditional bulge microlensing fields. Our primary analysis yields a Jovian planet with Mp=0.59-0.05+0.15MJ at a projected orbital separation r perpendicular to=1.4-0.3+0.8 au, and the host is a similar to 1.1 M circle dot turnoff star at similar to 1.3 kpc. At r 'approximate to 14 , the host is far brighter than any previously discovered microlensing planet host, opening up the opportunity to test the microlensing model with radial velocity (RV) observations. RV data can be used to measure the planet's orbital period and eccentricity, and they also enable searching for inner planets of the microlensing cold Jupiter, as expected from the "inner-outer correlation" inferred from Kepler and RV discoveries. Furthermore, we show that Gaia astrometric microlensing will not only allow precise measurements of its angular Einstein radius theta E but also directly measure the microlens parallax vector and unambiguously break a geometric light-curve degeneracy, leading to the definitive characterization of the lens system.
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    OGLE-2019-BLG-0825: Constraints on the Source System and Effect on Binary-lens Parameters Arising from a Five-day Xallarap Effect in a Candidate Planetary Microlensing Event
    (2023) Satoh, Yuki; Koshimoto, Naoki; Bennett, David A.; Sumi, Takahiro; Rattenbury, Nicholas; Suzuki, Daisuke; Miyazaki, Shota; Bond, Ian; Udalski, Andrzej; Gould, Andrew; Bozza, Valerio; Dominik, Martin; Hirao, Yuki; Kondo, Iona; Kirikawa, Rintaro; Hamada, Ryusei; Abe, Fumio; Barry, Richard; Bhattacharya, Aparna; Fujii, Hirosane; Fukui, Akihiko; Fujita, Katsuki; Ikeno, Tomoya; Ishitani Silva, Stela; Itow, Yoshitaka; Matsubara, Yutaka; Matsumoto, Sho; Muraki, Yasushi; Niwa, Kosuke; Okamura, Arisa J.; Olmschenk, Greg; Ranc, Clement; Toda, Taiga; Tomoyoshi, Mio; Tristram, Paul; Vandorou, Aikaterini; Yama, Hibiki; Yamashita, Kansuke; Mroz, Przemek; Poleski, Radoslaw; Skowron, Jan; Szymanski, Michal K.; Poleski, Radek A.; Soszynski, Igor; Pietrukowicz, Pawel; Kozlowski, Szymon; Ulaczyk, Krzysztof D.; Rybicki, Krzysztof; Iwanek, Patryk; Wrona, Marcin; Gromadzki, Mariusz; Albrow, Michael; Chung, Sun-Ju; Han, Cheongho; Hwang, Kyu-Ha; Kim, Doeon; Jung, Youn Kil; Kim, Hyoun Woo C.; Ryu, Yoon-Hyun; Shin, In-Gu; Shvartzvald, Yossi; Yang, Hongjing; Yee, Jennifer; Zang, Weicheng; Cha, Sang-Mok; Kim, Dong-Jin; Kim, Seung-Lee W.; Lee, Chung-Uk G.; Lee, Dong-Joo; Lee, Yongseok; Park, Byeong-Gon; Pogge, Richard; Jorgensen, Uffe; Longa-Pena, Penelope; Sajadian, Sedighe; Skottfelt, Jesper; Snodgrass, Colin; Tregloan-Reed, Jeremy; Bach-Moller, Nanna; Burgdorf, Martin; D'Ago, Giuseppe; Haikala, Lauri; Hitchcock, James; Hundertmark, Markus; Khalouei, Elahe; Peixinho, Nuno; Rahvar, Sohrab; Southworth, John; Spyratos, Petros
    We present an analysis of microlensing event OGLE-2019-BLG-0825. This event was identified as a planetary candidate by preliminary modeling. We find that significant residuals from the best-fit static binary-lens model exist and a xallarap effect can fit the residuals very well and significantly improves chi (2) values. On the other hand, by including the xallarap effect in our models, we find that binary-lens parameters such as mass ratio, q, and separation, s, cannot be constrained well. However, we also find that the parameters for the source system such as the orbital period and semimajor axis are consistent between all the models we analyzed. We therefore constrain the properties of the source system better than the properties of the lens system. The source system comprises a G-type main-sequence star orbited by a brown dwarf with a period of P similar to 5 days. This analysis is the first to demonstrate that the xallarap effect does affect binary-lens parameters in planetary events. It would not be common for the presence or absence of the xallarap effect to affect lens parameters in events with long orbital periods of the source system or events with transits to caustics, but in other cases, such as this event, the xallarap effect can affect binary-lens parameters.
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    THE SPITZER MICROLENSING PROGRAM AS A PROBE FOR GLOBULAR CLUSTER PLANETS: ANALYSIS OF OGLE-2015-BLG-0448
    (2016) Poleski, Radoslaw; Zhu, Wei; Christie, Grant W.; Udalski, Andrzej; Gould, Andrew; Bachelet, Etienne; Skottfelt, Jesper; Novati, Sebastiano Calchi; Szymanski, M. K.; Soszynski, I.; Pietrzynski, G.; Wyrzykowski, L.; Ulaczyk, K.; Pietrukowicz, P.; Kozlowski, Szymon; Skowron, J.; Mroz, P.; Pawlak, M.; Beichman, C.; Bryden, G.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Pogge, R. W.; Shvartzvald, Y.; Wibking, B.; Yee, J. C.; Beatty, T. G.; Eastman, J. D.; Drummond, J.; Friedmann, M.; Henderson, M.; Johnson, J. A.; Kaspi, S.; Maoz, D.; McCormick, J.; McCrady, N.; Natusch, T.; Ngan, H.; Porritt, I.; Relles, H. M.; Sliski, D. H.; Tan, T. G.; Wittenmyer, R. A.; Wright, J. T.; Street, R. A.; Tsapras, Y.; Bramich, D. M.; Horne, K.; Snodgrass, C.; Steele, I. A.; Menzies, J.; Jaimes, R. Figuera; Wambsganss, J.; Schmidt, R.; Cassan, A.; Ranc, C.; Mao, S.; Bozza, V.; Dominik, M.; Hundertmark, M. P. G.; Jorgensen, U. G.; Andersen, M. I.; Burgdorf, M. J.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Gu, S. H.; Hinse, T. C.; Kains, N.; Kerins, E.; Korhonen, H.; Kuffmeier, M.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Rasmussen, R. T.; Scarpetta, G.; Southworth, J.; Surdej, J.; Unda-Sanzana, E.; Verma, P.; von Essen, C.; Wang, Y. B.; Wertz, O.
    The microlensing event OGLE-2015-BLG-0448 was observed by Spitzer and lay within the tidal radius of the globular cluster NGC 6558. The event had moderate magnification and was intensively observed, hence it had the potential to probe the distribution of planets in globular clusters. We measure the proper motion of NGC 6558 (mu(cl) (N, E) = (+0.36 +/- 0.10, +1.42 +/- 0.10) mas yr(-1)) as well as the source and show that the lens is not a cluster member. Even though this particular event does not probe the distribution of planets in globular clusters, other potential cluster lens events can be verified using our methodology. Additionally, we find that microlens parallax measured using Optical Gravitational Lens Experiment (OGLE) photometry is consistent with the value found based on the light curve displacement between the Earth and Spitzer.