Four microlensing giant planets detected through signals produced by minor-image perturbations

¹ Department of Physics, Chungbuk National University, Cheongju 28644, Republic of Korea
e-mail: cheongho@astroph.chungbuk.ac.kr
² Institute of Natural and Mathematical Science, Massey University, Auckland 0745, New Zealand
³ Korea Astronomy and Space Science Institute, Daejon 34055, Republic of Korea
⁴ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁵ Department of Astronomy, The Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USA
⁶ University of Canterbury, Department of Physics and Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
⁷ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel
⁸ Center for Astrophysics | Harvard & Smithsonian 60 Garden St., Cambridge, MA 02138, USA
⁹ Department of Astronomy and Tsinghua Centre for Astrophysics, Tsinghua University, Beijing 100084, PR China
¹⁰ School of Space Research, Kyung Hee University, Yongin, Kyeonggi 17104, Republic of Korea
¹¹ Institute for Space-Earth Environmental Research, Nagoya University, Nagoya 464-8601, Japan
¹² Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
¹³ Code 667, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
¹⁴ Department of Astronomy, University of Maryland, College Park, MD 20742, USA
¹⁵ Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
¹⁶ Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
¹⁷ Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan
¹⁸ Oak Ridge Associated Universities, Oak Ridge, TN 37830, USA
¹⁹ Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210, Japan
²⁰ Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
²¹ Department of Physics, University of Auckland, Private Bag 92019, Auckland, New Zealand
²² University of Canterbury Mt. John Observatory, PO Box 56, Lake Tekapo 8770, New Zealand
²³ IPAC, Mail Code 100-22, Caltech, 1200 E. California Blvd., Pasadena, CA 91125, USA
²⁴ Dipartimento di Fisica “E.R. Caianiello”, Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy
²⁵ Instituto Nazionale di Fisica Nucleare, Sezione di Napoli, Via Cintia, 80126 Napoli, Italy
²⁶ Institute of Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, 87-100 Toruń, Poland
²⁷ Las Cumbres Observatory Global Telescope Network, Inc., 6740 Cortona Drive, Suite 102, Goleta, CA 93117, USA
²⁸ Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut, Mönchhofstr. 12–14, 69120 Heidelberg, Germany
²⁹ Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
³⁰ Millennium Institute of Astrophysics MAS, Nuncio Monsenor Sotero Sanz 100, Of. 104, Providencia, Santiago, Chile
³¹ Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
³² Institut d’Astrophysique de Paris, Sorbonne Université, CNRS, UMR 7095, 98 bis bd Arago, 75014 Paris, France
³³ University of St Andrews, Centre for Exoplanet Science, School of Physics & Astronomy, North Haugh, St Andrews KY16 9SS, UK
³⁴ Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
³⁵ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel
³⁶ Departamento de Matemática y Física Aplicadas, Facultad de Ingeniería, Universidad Católica de la Santísima Concepción, Alonso de Rivera 2850, Concepción, Chile

Received: 3 April 2024
Accepted: 10 June 2024

Abstract

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_⊙, 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.