One Planet or Two Planets? The Ultra-sensitive Extreme-magnification Microlensing Event KMT-2019-BLG-1953. (arXiv:2002.05310v1 [astro-ph.EP])

One Planet or Two Planets? The Ultra-sensitive Extreme-magnification Microlensing Event KMT-2019-BLG-1953. (arXiv:2002.05310v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Han_C/0/1/0/all/0/1">Cheongho Han</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_D/0/1/0/all/0/1">Doeon Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jung_Y/0/1/0/all/0/1">Youn Kil Jung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gould_A/0/1/0/all/0/1">Andrew Gould</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bond_I/0/1/0/all/0/1">Ian A. Bond</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Albrow_M/0/1/0/all/0/1">Michael D. Albrow</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chung_S/0/1/0/all/0/1">Sun-Ju Chung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hwang_K/0/1/0/all/0/1">Kyu-Ha Hwang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_C/0/1/0/all/0/1">Chung-Uk Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ryu_Y/0/1/0/all/0/1">Yoon-Hyun Ryu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shin_I/0/1/0/all/0/1">In-Gu Shin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shvartzvald_Y/0/1/0/all/0/1">Yossi Shvartzvald</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yee_J/0/1/0/all/0/1">Jennifer C. Yee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zang_W/0/1/0/all/0/1">Weicheng Zang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cha_S/0/1/0/all/0/1">Sang-Mok Cha</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_D/0/1/0/all/0/1">Dong-Jin Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_H/0/1/0/all/0/1">Hyoun-Woo Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_S/0/1/0/all/0/1">Seung-Lee Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_D/0/1/0/all/0/1">Dong-Joo Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_Y/0/1/0/all/0/1">Yongseok Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Park_B/0/1/0/all/0/1">Byeong-Gon Park</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pogge_R/0/1/0/all/0/1">Richard W. Pogge</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_W/0/1/0/all/0/1">Woong-Tae Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Abe_F/0/1/0/all/0/1">Fumio Abe</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barry_R/0/1/0/all/0/1">Richard Barry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bennett_D/0/1/0/all/0/1">David P. Bennett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bhattacharya_A/0/1/0/all/0/1">Aparna Bhattacharya</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Donachie_M/0/1/0/all/0/1">Martin Donachie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fujii_H/0/1/0/all/0/1">Hirosane Fujii</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fukui_A/0/1/0/all/0/1">Akihiko Fukui</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Itow_Y/0/1/0/all/0/1">Yoshitaka Itow</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hirao_Y/0/1/0/all/0/1">Yuki Hirao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kirikawa_R/0/1/0/all/0/1">Rintaro Kirikawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kondo_I/0/1/0/all/0/1">Iona Kondo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Koshimoto_N/0/1/0/all/0/1">Naoki Koshimoto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_M/0/1/0/all/0/1">Man Cheung Alex Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Matsubara_Y/0/1/0/all/0/1">Yutaka Matsubara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Muraki_Y/0/1/0/all/0/1">Yasushi Muraki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miyazaki_S/0/1/0/all/0/1">Shota Miyazaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nagakane_M/0/1/0/all/0/1">Masayuki Nagakane</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ranc_C/0/1/0/all/0/1">Cl&#xe9;ment Ranc</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rattenbury_N/0/1/0/all/0/1">Nicholas J. Rattenbury</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Satoh_Y/0/1/0/all/0/1">Yuki Satoh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shoji_H/0/1/0/all/0/1">Hikaru Shoji</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Suematsu_H/0/1/0/all/0/1">Haruno Suematsu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sumi_T/0/1/0/all/0/1">Takahiro Sumi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Suzuki_D/0/1/0/all/0/1">Daisuke Suzuki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tanaka_Y/0/1/0/all/0/1">Yuzuru Tanaka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tristram_P/0/1/0/all/0/1">Paul J. Tristram</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yamawaki_T/0/1/0/all/0/1">Tsubasa Yamawaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yonehara_A/0/1/0/all/0/1">Atsunori Yonehara</a>

We report a strong candidate multiplanetary system found by analyzing a very
high-magnification ($Asim 900$) microlensing event KMT-2019-BLG-1953. A
single-lens single-source (1L1S) model appears to approximately delineate the
observed light curve, but the residuals from the model exhibit small but
obvious deviations in the peak region. Although models with a binary lens
(2L1S) and binary source (1L2S) improve the fit, there still remain small
residuals from the models, and these residuals can be explained by either
triple-lens (3L1S) or binary-lens binary-source (2L2S) models. Among the two
models, we judge that the 3L1S model provides a more plausible interpretation
first because the signature of the second planet according to the 3L1S solution
appears in the region where it is expected, i.e., around the peak of a very
high-magnification event, and second because the 2L2S model is physically
implausible. From the 3L1S modeling, we find four sets of solutions caused by
the close/wide degeneracies in the planet separations from the host, $s_2$ and
$s_3$. From Bayesian analysis, we estimate that the host of the planets has a
mass of $M_{rm host}=0.31^{+0.37}_{-0.17}~M_odot$ and that the planetary
system is located at a distance of $D_{rm L}=7.04^{+1.10}_{-1.33}~{rm kpc}$
toward the Galactic center. The mass of the first planet, $M_2$, is in the
range of $0.42 lesssim M_2/M_{rm J}lesssim 0.62$ and that of the second
planet, $M_3$, is in the ranges of $0.27 lesssim M_3/M_{rm J}lesssim 0.48$
for solutions with $s_3<1.0$ and $2.1 lesssim M_3/M_{rm J} lesssim 2.8$ for
solutions with $s_3>1.0$.

We report a strong candidate multiplanetary system found by analyzing a very
high-magnification ($Asim 900$) microlensing event KMT-2019-BLG-1953. A
single-lens single-source (1L1S) model appears to approximately delineate the
observed light curve, but the residuals from the model exhibit small but
obvious deviations in the peak region. Although models with a binary lens
(2L1S) and binary source (1L2S) improve the fit, there still remain small
residuals from the models, and these residuals can be explained by either
triple-lens (3L1S) or binary-lens binary-source (2L2S) models. Among the two
models, we judge that the 3L1S model provides a more plausible interpretation
first because the signature of the second planet according to the 3L1S solution
appears in the region where it is expected, i.e., around the peak of a very
high-magnification event, and second because the 2L2S model is physically
implausible. From the 3L1S modeling, we find four sets of solutions caused by
the close/wide degeneracies in the planet separations from the host, $s_2$ and
$s_3$. From Bayesian analysis, we estimate that the host of the planets has a
mass of $M_{rm host}=0.31^{+0.37}_{-0.17}~M_odot$ and that the planetary
system is located at a distance of $D_{rm L}=7.04^{+1.10}_{-1.33}~{rm kpc}$
toward the Galactic center. The mass of the first planet, $M_2$, is in the
range of $0.42 lesssim M_2/M_{rm J}lesssim 0.62$ and that of the second
planet, $M_3$, is in the ranges of $0.27 lesssim M_3/M_{rm J}lesssim 0.48$
for solutions with $s_3<1.0$ and $2.1 lesssim M_3/M_{rm J} lesssim 2.8$ for
solutions with $s_3>1.0$.

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