Browsing by Author "Beichman C"
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- ItemAnalysis of the Full Spitzer Microlensing Sample. I. Dark Remnant Candidates and Gaia Predictions(American Astronomical Society, 2024-11-10) Rybicki KA; Shvartzvald Y; Yee JC; Novati SC; Ofek EO; Bond IA; Beichman C; Bryden G; Carey S; Henderson C; Zhu W; Fausnaugh MM; Wibking B; Udalski A; Poleski R; Mróz P; Szymański MK; Soszyński I; Pietrukowicz P; Kozłowski S; Skowron J; Ulaczyk K; Iwanek P; Wrona M; Ryu Y-H; Albrow MD; Chung S-J; Gould A; Han C-H; Hwang K-H; Jung YK; Shin I-G; Yang H; Zang W; Cha S-M; Kim D-J; Kim H-W; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge RW; Abe F; Barry R; Bennett DP; Bhattacharya A; Fukui A; Hamada R; Hamada S; Hamasaki N; Hirao Y; Ishitani Silva S; Itow Y; Kirikawa R; Koshimoto N; Matsubara Y; Miyazaki S; Muraki Y; Nagai T; Nunota K; Olmschenk G; Ranc C; Rattenbury NJ; Satoh YK; Sumi T; Suzuki D; Tristram PJ; Vandorou A; Yama H; Wyrzykowski Ł; Howil K; Kruszyńska KIn the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of ∼950 microlensing events observed by the Spitzer Space Telescope between 2014 and 2019. In this study we focus on a subsample of nine microlensing events, selected based on their long timescales, small microlensing parallaxes, and joint observations by the Gaia mission, to increase the probability that the chosen lenses are massive and the mass is measurable. Among the selected events we identify lensing black holes and neutron star candidates, with potential confirmation through forthcoming release of the Gaia time-series astrometry in 2026. Utilizing Bayesian analysis and Galactic models, along with the Gaia Data Release 3 proper-motion data, four good candidates for dark remnants were identified: OGLE-2016-BLG-0293, OGLE-2018-BLG-0483, OGLE-2018-BLG-0662, and OGLE-2015-BLG-0149, with lens masses of 3.0-1.3+1.8M☉, 4.7-2.1+3.2 M☉, 3.15-0.64+0..66 M☉ and 1.40-0.55+0.75 M☉, respectively. Notably, the first two candidates are expected to exhibit astrometric microlensing signals detectable by Gaia, offering the prospect of validating the lens masses. The methodologies developed in this work will be applied to the full Spitzer microlensing sample, populating and analyzing the timescale (tE) versus parallax (πE) diagram to derive constraints on the population of lenses in general and massive remnants in particular.
- ItemKepler K2 Campaign 9 – II. First space-based discovery of an exoplanet using microlensing(Oxford University Press, 2023-04-01) Specht D; Poleski R; Penny MT; Kerins E; McDonald I; Chung-Uk L; Udalski A; Bond IA; Shvartzvald Y; Zang W; Street RA; Hogg DW; Gaudi BS; Barclay T; Barentsen G; Howell SB; Mullally F; Henderson CB; Bryson ST; Caldwell DA; Haas MR; Van Cleve JE; Larson K; McCalmont K; Peterson C; Putnam D; Ross S; Packard M; Reedy L; Albrow MD; Sun-Ju C; Jung YK; Gould A; Han C; Kyu-Ha H; Yoon-Hyun R; In-Gu S; Yang H; Yee JC; Sang-Mok C; Dong-Jin K; Seung-Lee K; Dong-Joo L; Lee Y; Byeong-Gon P; Pogge RW; Szymański MK; Soszyński I; Ulaczyk K; Pietrukowicz P; Kozłowski SZ; Skowron J; Mróz P; Mao S; Fouqué P; Zhu W; Abe F; Barry R; Bennett DP; Bhattacharya A; Fukui A; Fujii H; Hirao Y; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Matsubara Y; Matsumoto S; Miyazaki S; Muraki Y; Olmschenk G; Ranc C; Okamura A; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Silva SI; Toda T; Tristram PJ; Vandorou A; Yama H; Beichman C; Bryden G; Novati SCWe present K2-2016-BLG-0005Lb, a densely sampled, planetary binary caustic-crossing microlensing event found from a blind search of data gathered from Campaign 9 of the Kepler K2 mission (K2C9). K2-2016-BLG-0005Lb is the first bound microlensing exoplanet discovered from space-based data. The event has caustic entry and exit points that are resolved in the K2C9 data, enabling the lens-source relative proper motion to be measured. We have fitted a binary microlens model to the Kepler data and to simultaneous observations from multiple ground-based surveys. Whilst the ground-based data only sparsely sample the binary caustic, they provide a clear detection of parallax that allows us to break completely the microlensing mass-position-velocity degeneracy and measure the planet’s mass directly. We find a host mass of 0.58 ± 0.04 M and a planetary mass of 1.1 ± 0.1 MJ. The system lies at a distance of 5.2 ± 0.2 kpc from Earth towards the Galactic bulge, more than twice the distance of the previous most distant planet found by Kepler. The sky-projected separation of the planet from its host is found to be 4.2 ± 0.3 au which, for circular orbits, deprojects to a host separation a = 4.4+−0149 au and orbital period P = 13+−29 yr. This makes K2-2016-BLG-0005Lb a close Jupiter analogue orbiting a low-mass host star. According to current planet formation models, this system is very close to the host mass threshold below which Jupiters are not expected to form. Upcoming space-based exoplanet microlensing surveys by NASA’s Nancy Grace Roman Space Telescope and, possibly, ESA’s Euclid mission, will provide demanding tests of current planet formation models.
- ItemSystematic KMTNet planetary anomaly search: V. Complete sample of 2018 prime-field(EDP Sciences, 2022-08-08) Gould A; Han C; Zang W; Yang H; Hwang K-H; Udalski A; Bond IA; Albrow MD; Chung S-J; Jung YK; Ryu Y-H; Shin I-G; Shvartzvald Y; Yee JC; Cha S-M; Kim D-J; Kim H-W; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge RW; Mróz P; Szymanski MK; Skowron J; Poleski R; Soszyński I; Pietrukowicz P; Kozłowski S; Ulaczyk K; Rybicki KA; Iwanek P; Wrona M; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hirao Y; Silva SI; Kirikawa R; Kondo I; Koshimoto N; Matsubara Y; Matsumoto S; Miyazaki S; Muraki Y; Okamura A; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Toda T; Tristram PJ; Vandorou A; Yama H; Beichman C; Bryden G; Novati SC; Gaudi BS; Henderson CB; Penny MT; Jacklin S; Stassun KGWe complete the analysis of all 2018 prime-field microlensing planets identified by the Korea Microlensing Telescope Network (KMTNet) Anomaly Finder. Among the ten previously unpublished events with clear planetary solutions, eight are either unambiguously planetary or are very likely to be planetary in nature: OGLE-2018-BLG-1126, KMT-2018-BLG-2004, OGLE-2018-BLG-1647, OGLE-2018-BLG-1367, OGLE-2018-BLG-1544, OGLE-2018-BLG-0932, OGLE-2018-BLG-1212, and KMT-2018-BLG-2718. Combined with the four previously published new Anomaly Finder events and 12 previously published (or in preparation) planets that were discovered by eye, this makes a total of 24 2018 prime-field planets discovered or recovered by Anomaly Finder. Together with a paper in preparation on 2018 subprime planets, this work lays the basis for the first statistical analysis of the planet mass-ratio function based on planets identified in KMTNet data. By systematically applying the heuristic analysis to each event, we identified the small modification in their formalism that is needed to unify the so-called close-wide and inner-outer degeneracies.