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

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Li, S-S and Zang, W and Udalski, A and Shvartzvald, Y and Huber, D and Lee, C-U and Sumi, T and Gould, A and Mao, S and Fouque, P and Wang, T and Dong, S and Jorgensen, UG and Ciole, A and Mroz, P and Szymanski, MK and Skowron, J and Poleski, R and Soszynski, I and Pietrukowicz, P and Kozlowski, S and Ulaczyk, K and Rybicki, KA and Iwanek, P and Yee, JC and Novati, SC and Beichman, CA and Bryden, G and Carey, S and Gaudi, BS and Henderson, CB and Zhu, W and Albrow, MD and Chung, S-J and Han, C and Hwang, K-H and Jung, YK and Ryu, Y-H and Shin, I-G and Cha, S-M and Kim, D-J and Kim, H-W and Kim, S-L and Lee, D-J and Lee, Y and Park, B-G and Pogge, RW and Bond, IA and Abe, F and Barry, R and Bennett, DP and Bhattacharya, A and Donachie, M and Fukui, A and Hirao, Y and Itow, Y and Kondo, I and Koshimoto, N and Li, MCA and Matsubara, Y and Muraki, Y and Miyazaki, S and Nagakane, M and Ranc, C and Rattenbury, NJ and Suematsu, H and Sullivan, DJ and Suzuki, D and Tristram, PJ and Yonehara, A and Christie, G and Drummond, J and Green, J and Hennerley, S and Natusch, T and Porritt, I and Bachelet, E and Maoz, D and Street, RA and Tsapras, Y and Bozza, V and Dominik, M and Hundertmark, M and Peixinho, N and Sajadian, S and Burgdorf, MJ and Evans, DF and Jaimes, RF and Fujii, YI and Haikala, LK and Helling, C and Henning, T and Hinse, TC and Mancini, L and Longa-Pena, P and Rahvar, S and Rabus, M and Skottfelt, J and Snodgrass, C and Southworth, J and Unda-Sanzana, E and von Essen, C and Beaulieu, J-P and Blackman, J and Hill, K, OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing, Monthly Notices of the Royal Astronomical Society, 488, (3) pp. 3308-3323. ISSN 0035-8711 (2019) [Refereed Article]


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Copyright 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

DOI: doi:10.1093/mnras/stz1873

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 time-scale of ∼9 d. The asteroseismic analysis also provides us source properties including the source angular size (∼27 μas) and distance (∼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 χ2 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 ∼0.045 M brown dwarf at distance ∼9.0 kpc, or a ∼0.073 M ultracool dwarf at distance ∼9.8 kpc. Combining the estimated lens properties with a Bayesian analysis using a Galactic model, we find a ∼35 per cent probability for the lens to be a bulge object and ∼65 per cent to be a background disc object.

Item Details

Item Type:Refereed Article
Keywords:asteroseismology, gravitational lensing: micro, stars: fundamental parameters, stars: oscillations
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Stellar Astronomy and Planetary Systems
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
UTAS Author:Ciole, A (Associate Professor Andrew Cole)
ID Code:136288
Year Published:2019
Funding Support:Australian Research Council (LE110100055)
Web of Science® Times Cited:2
Deposited By:Physics
Deposited On:2019-12-12
Last Modified:2020-06-02
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