Rintaro Kirikawa
A5045035835- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Atmospheric Ozone and Climate
- Pulsars and Gravitational Waves Research
- Adaptive optics and wavefront sensing
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- Advanced Frequency and Time Standards
- Mechanics and Biomechanics Studies
- History and Developments in Astronomy
- SAS software applications and methods
- Geochemistry and Geologic Mapping
- Spacecraft Design and Technology
- Space Exploration and Technology
- Space Science and Extraterrestrial Life
- Galaxies: Formation, Evolution, Phenomena
Osaka University
2020-2025
Osaka Health Science University
2025
Ministry of Agriculture and Natural Resource
2021-2023
Abstract We present the analysis of five black hole candidates identified from gravitational microlensing surveys. Hubble Space Telescope astrometric data and densely sampled light curves ground-based surveys are fit with a single-source, single-lens model in order to measure mass luminosity each lens determine if it is hole. One targets (OGLE-2011-BLG-0462/MOA-2011-BLG-191 or OB110462 for short) shows significant >1 mas coherent shift, little no flux, has an inferred 1.6–4.4 M ⊙ . This...
Abstract We present the first measurement of mass function free-floating planets (FFPs), or very wide orbit down to an Earth mass, from MOA-II microlensing survey in 2006–2014. Six events are likely be due with Einstein radius crossing times t E < 0.5 days, and shortest has = 0.057 ± 0.016 days angular θ 0.90 0.14 μ as. measure detection efficiency depending on both image-level simulations for time. These short well modeled by a power-law function, <mml:math...
Abstract We report the discoveries of low-mass free-floating planet (FFP) candidates from analysis 2006–2014 MOA-II Galactic bulge survey data. In this data set, we found 6111 microlensing and identified a statistical sample consisting 3535 high-quality single-lens events with Einstein radius crossing times in range 0.057 < t E /days 757, including 13 that show clear finite-source effects angular radii 0.90 θ / μ as 332.54. Two 12 1 day have significant effects, one event, MOA-9y-5919, =...
Exoplanets classified as super-Earths are commonly observed on short-period orbits, close to their host stars, but abundance wider orbits is poorly constrained. Gravitational microlensing sensitive exoplanets wide orbits. We the event OGLE-2016-BLG-0007, which indicates an exoplanet with a planet-to-star mass ratio roughly double Earth-Sun ratio, orbit longer than Saturn's. combined this larger sample from survey determine distribution of ratios for planets infer that there ~0.35 super-Earth...
Abstract In order to exhume the buried signatures of “missing planetary caustics” in Korea Microlensing Telescope Network (KMTNet) data, we conducted a systematic anomaly search residuals from point-source point-lens fits, based on modified version KMTNet EventFinder algorithm. This revealed lowest-mass-ratio caustic date microlensing event OGLE-2019-BLG-1053, for which signal had not been noticed before. The system has planet–host mass ratio q = (1.25 ± 0.13) × 10 −5 . A Bayesian analysis...
Abstract We apply the automated AnomalyFinder algorithm of Paper I to 2018–2019 light curves from ≃13 deg 2 covered by six KMTNet prime fields, with cadences Γ ≥ hr −1 . find a total 11 planets mass ratios q < × 10 −4 , including 6 newly discovered planets, 1 planet that was reported in I, and recovery 4 previously planets. One new OGLE-2018-BLG-0977Lb, is planetary caustic event, while other five (OGLE-2018-BLG-0506Lb, OGLE-2018-BLG-0516Lb, OGLE-2019-BLG-1492Lb, KMT-2019-BLG-0253,...
We complete the analysis of all 2018 prime-field microlensing planets identified by Korea Microlensing Telescope Network (KMTNet) Anomaly Finder. Among ten previously unpublished events with clear planetary solutions, eight are either unambiguously or very likely to be 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 four published new Finder 12 (or...
Abstract We report the analysis of OGLE-2019-BLG-0960, which contains smallest mass-ratio microlensing planet found to date ( q = 1.2–1.6 × 10 −5 at 1 σ ). Although there is substantial uncertainty in satellite parallax measured by Spitzer, measurement annual effect combined with finite source allows us determine mass host star M L 0.3–0.6 ⊙ ), its m p 1.4–3.1 ⊕ projected separation between and a ⊥ 1.2–2.3 au), distance lens system D 0.6–1.2 kpc). The plausibly blend, could be checked...
ABSTRACT 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 project systematically apply the new pipeline historic microlensing events, search buried planetary signals. report discovery of such planet candidate event MOA-2019-BLG-421/KMT-2019-BLG-2991. The anomalous signal can be explained by either around lens star or orbital motion source star. For interpretation, despite many...
An Earth-mass planet in a time of COVID-19: KMT-2020-BLG-0414Lb, Weicheng Zang, Cheongho Han, Iona Kondo, Jennifer C. Yee, Chung-Uk Lee, Andrew Gould, Shude Mao, Leandro de Almeida, Yossi Shvartzvald, Xiangyu Zhang, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Seung-Lee Dong-Joo Yongseok Byeong-Gon Park, Richard W. Pogge, John Drummond, Thiam-Guan Tan, José Dias do Nascimento Júnior, Dan Maoz, Matthew T. Penny,...
Abstract As a part of the “Systematic KMTNet Planetary Anomaly Search” series, we report five new planets (namely, OGLE-2016-BLG-1635Lb, MOA-2016-BLG-532Lb, KMT-2016-BLG-0625Lb, OGLE-2016-BLG-1850Lb, and KMT-2016-BLG-1751Lb) one planet candidate (KMT-2016-BLG-1855), which were found by searching 2016 prime fields. These buried show wide range masses from Earth-class to super-Jupiter-class are located in both disk bulge. The ultimate goal this series is build complete sample. Because our work...
We examined the anomalies in light curves of lensing events MOA-2022-BLG-033, KMT-2023-BLG-0119, and KMT-2023-BLG-1896. conducted detailed modeling to uncover nature anomalies. This revealed that all signals originated from planetary companions primary lens. The planet-to-host mass ratios are very low: $q\sim 7.5\times 10^{-5}$ for 3.6\times 10^{-4}$ 6.9\times occurred as source passed through negative deviation region behind central caustic along planet-host axis. solutions subject a common...
We examined the anomalies in light curves of lensing events MOA-2022-BLG-033, KMT-2023-BLG-0119, and KMT-2023-BLG-1896. These share similar traits: they occur near peak moderately to highly magnified display a distinct short-term dip feature. conducted detailed modeling uncover nature anomalies. This revealed that all signals originated from planetary companions primary lens. The planet-to-host mass ratios are very low: q∼ 7.5 for $q∼ 3.6 $ 6.9 occurred as source passed through negative...
Aims. We analyze the anomalies appearing in light curves of three microlensing events MOA-2022-BLG-563, KMT-2023-BLG-0469, and KMT-2023-BLG-0735. The exhibit common short-term dip features that appear near peak. Methods. From detailed analyses curves, we find were produced by planets accompanied lenses events. For all events, estimated mass ratios between planet host are on order 10 −4 : q ~ 8 × for MOA-2022-BLG-563L, 2.5 KMT-2023-BLG-0469L, 1.9 KMT-2023-BLG-0735L. interpretations subject to...
Abstract Following Shin et al. (2023b), which is a part of the “Systematic KMTNet Planetary Anomaly Search” series (i.e., search for planets in 2016 prime fields), we conduct systematic subprime fields using semi-machine-based algorithm to identify hidden anomalous events missed by conventional by-eye search. We find four new and seven planet candidates that were buried archive. The are OGLE-2016-BLG-1598Lb, OGLE-2016-BLG-1800Lb, MOA-2016-BLG-526Lb, KMT-2016-BLG-2321Lb, show typical...
The high-magnification microlensing event KMT-2021-BLG-1077 exhibits a subtle and complex anomaly pattern in the region around peak. We analyze lensing light curve of with aim revealing nature anomaly. test various models combination several interpretations. find that cannot be explained by usual three-body (2L1S 1L2S) models. 2L2S model improves fit compared to models, but it still leaves noticeable residuals. On other hand, 3L1S interpretation yields explaining all major anomalous features...
Follow-up observations of high-magnification gravitational microlensing events can fully exploit their intrinsic sensitivity to detect extrasolar planets, especially those with small mass ratios. To make followup more uniform and efficient, we develop a system, HighMagFinder, based on the real-time data from Korean Microlensing Telescope Network (KMTNet) automatically alert possible ongoing events. We started new phase follow-up help HighMagFinder in 2021. Here report discovery two planets...
We describe the optical alignment method for Prime-focus Infrared Microlensing Experiment (PRIME) telescope which is a prime-focus near-infrared (NIR) with wide field of view microlensing planet survey toward Galactic center that major task PRIME project. There are three steps alignment: preliminary by laser tracker, fine intra- and extra-focal (IFEF) image analysis technique, complementary Hartmann test. demonstrated first two work well test conducted in laboratory Japan. The was installed...
We present the first measurement of mass function free-floating planets (FFP) or very wide orbit down to an Earth mass, from MOA-II microlensing survey in 2006-2014. Six events are likely be due with Einstein radius crossing times, $t_{\rm E}<0.5$days, and shortest has E} = 0.057\pm 0.016$days angular $\theta_{\rm 0.90\pm 0.14\mu$as. measure detection efficiency depending on both E}$ image level simulations for time. These short well modeled by a power-law function, $dN_4/d\log M...
We present the analysis of a very high-magnification ($A\sim 900$) microlensing event KMT-2019-BLG-1953. A single-lens single-source (1L1S) model appears to approximately delineate observed light curve, but residuals from exhibit small obvious deviations in peak region. binary lens (2L1S) with mass ratio $q\sim 2\times 10^{-3}$ improves fits by $\Delta\chi^2=181.8$, indicating that possesses planetary companion. From additional modeling introducing an extra component (3L1S model) and source...
We report the analysis of planetary microlensing event OGLE-2018-BLG-1185, which was observed by a large number ground-based telescopes and $Spitzer$ Space Telescope. The light curve indicates low planet-host star mass ratio $q = (6.9 \pm 0.2) \times 10^{-5}$, is near peak wide-orbit exoplanet mass-ratio distribution. estimate host planet masses with Bayesian using measured angular Einstein radius under assumption that stars all have an equal probability to this planet. flux variation...
We investigate the gravitational microlensing event KMT-2019-BLG-1715, of which light curve shows two short-term anomalies from a caustic-crossing binary-lensing curve: one with large deviation and other small deviation. identify five pairs solutions, in are explained by adding an extra lens or source component addition to base binary-lens model. resolve degeneracies applying method, measured flux ratio between first second stars is compared deduced radii. Applying this method leaves single...
Abstract We show that the perturbation at peak of light curve microlensing event KMT-2019-BLG-0371 is explained by a model with mass ratio between host star and planet q ∼ 0.08. Due to short duration ( t E 6.5 days), secondary object in this system could potentially be massive giant planet. A Bayesian analysis shows most likely consists <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mi...
With the aim of finding short-term planetary signals, we investigated data collected from high-cadence microlensing surveys. From this investigation, found four systems with low planet-to-host mass ratios, including OGLE-2017-BLG-1691L, KMT-2021-BLG-0320L, KMT-2021-BLG-1303L, and KMT-2021-BLG-1554L. Despite short durations, ranging a few hours to couple days, signals were clearly detected by combined lensing It is that three have ratios order $10^{-4}$ other has ratio slightly greater than...
We report the discoveries of low-mass free-floating planet (FFP) candidates from analysis 2006-2014 MOA-II Galactic bulge survey data. In this dataset, we found 6,111 microlensing and identified a statistical sample consisting 3,535 high quality single lens events with Einstein radius crossing times in range $0.057 < t_{\rm E}/{\rm days} 757$, including 13 that show clear finite source effects angular radii $0.90<\theta_{\rm \mu as} <332.54$. Two 12 $t_{\rm E} 1$ day have significant...