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OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing

Research output: Contribution to journalArticle

  • Shun-Sheng Li
  • Weicheng Zang
  • Andrzej Udalski
  • Yossi Shvartzvald
  • Daniel Huber
  • Chung-Uk Lee
  • Takahiro Sumi
  • Andrew Gould
  • Shude Mao
  • Pascal Fouqué
  • Tianshu Wang
  • Subo Dong
  • Uffe G. Jørgensen
  • Andrew Cole
  • Przemek Mróz
  • Michał K. Szymański
  • Jan Skowron
  • Radosław Poleski
  • Igor Soszyński
  • Paweł Pietrukowicz
  • Szymon Kozłowski
  • Krzysztof Ulaczyk
  • Krzysztof A. Rybicki
  • Patryk Iwanek
  • Jennifer C. Yee
  • Sebastiano Calchi Novati
  • Charles A. Beichman
  • Geoffery Bryden
  • Sean Carey
  • B. Scott Gaudi
  • Calen B. Henderson
  • Wei Zhu
  • Michael D. Albrow
  • Sun-Ju Chung
  • Cheongho Han
  • Kyu-Ha Hwang
  • Youn Kil Jung
  • Yoon-Hyun Ryu
  • In-Gu Shin
  • Sang-Mok Cha
  • Dong-Jin Kim
  • Hyoun-Woo Kim
  • Seung-Lee Kim
  • Dong-Joo Lee
  • Yongseok Lee
  • Byeong-Gon Park
  • Richard W. Pogge
  • Ian A. Bond
  • Fumio Abe
  • Richard Barry
  • David P. Bennett
  • Aparna Bhattacharya
  • Martin Donachie
  • Akihiko Fukui
  • Yuki Hirao
  • Yoshitaka Itow
  • Iona Kondo
  • Naoki Koshimoto
  • Man Cheung Alex Li
  • Yutaka Matsubara
  • Yasushi Muraki
  • Shota Miyazaki
  • Masayuki Nagakane
  • Clément Ranc
  • Nicholas J. Rattenbury
  • Haruno Suematsu
  • Denis J. Sullivan
  • Daisuke Suzuki
  • Paul J. Tristram
  • Atsunori Yonehara
  • Grant Christie
  • John Drummond
  • Jonathan Green
  • Steve Hennerley
  • Tim Natusch
  • Ian Porritt
  • Etienne Bachelet
  • Dan Maoz
  • Rachel A. Street
  • Yiannis Tsapras
  • Valerio Bozza
  • Martin Dominik
  • Markus Hundertmark
  • Nuno Peixinho
  • Sedighe Sajadian
  • Martin J. Burgdorf
  • Daniel F. Evans
  • Roberto Figuera Jaimes
  • Yuri I. Fujii
  • Lauri K. Haikala
  • Christiane Helling
  • Thomas Henning
  • Tobias C. Hinse
  • Luigi Mancini
  • Penelope Longa-Peña
  • Sohrab Rahvar
  • Markus Rabus
  • Jesper Skottfelt
  • John Southworth
  • Eduardo Unda-Sanzana
  • Carolina von Essen
  • Jean-Phillipe Beaulieu
  • Joshua Blackman
  • Kym Hill

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Original languageEnglish
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Early online date10 Jul 2019
DOIs
Publication statusPublished - 1 Sep 2019

Abstract

We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 Spitzer microlensing campaign. This is a remarkable microlensing event because its source is photometrically bright and variable, which makes it possible to perform an asteroseismic analysis using ground-based data. We find that the source star is an oscillating red giant with average timescale of $\sim 9$ d. The asteroseismic analysis also provides us source properties including the source angular size ($\sim 27~\mu{\rm as}$) and distance ($\sim 11.5$ kpc), which are essential for inferring the properties of the lens. When fitting the light curve, we test the feasibility of Gaussian Processes (GPs) in handling the correlated noise caused by the variable source. We find that the parameters from the GP model are generally more loosely constrained than those from the traditional $\chi^2$ minimization method. We note that this event is the first microlensing system for which asteroseismology and GPs have been used to account for the variable source. With both finite-source effect and microlens parallax measured, we find that the lens is likely a $\sim 0.045~M_{\odot}$ brown dwarf at distance $\sim 9.0$ kpc, or a $\sim 0.073~M_{\odot}$ ultracool dwarf at distance $\sim 9.8$ kpc. Combining the estimated lens properties with a Bayesian analysis using a Galactic model, we find a $\sim 35$ per cent probability for the lens to be a bulge object and $\sim 65$ per cent to be a background disc object.

    Research areas

  • astro-ph.SR, astro-ph.EP

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