OGLE-2014-BLG-0289: Precise Characterization of a Quintuple-peak Gravitational Microlensing Event

Y Matsubara,N J Rattenbury ,S Kozłowski,Richard Barry ,A Fukui,J Wambsganß ,M Donachie,S Calchi Novati,Jennifer C Yee ,Cheongho Han ,Woong-Tae Kim ,C Snodgrass,P Mróz,Ł Wyrzykowski,N Kains,John Menzies ,A Yonehara,Wei Zhu ,Tōru Yamada ,P Evans,Naoki Koshimoto ,J Skowron,Charles Beichman ,M C A Li,P J Tristram,Sean Carey ,K Masuda,F Abe,Kohei Kawasaki ,Yuki Hirao ,G D’ago ,Y Itow,T Sumi,In-Gu Shin ,Aparna Bhattacharya ,R W Schmidt ,Shota Miyazaki ,V Bozza,R Poleski,M K Szymański,I A Steele,A Sharan,E Bachelet,D M Bramich,Clément Ranc ,K Ulaczyk,Y K Jung,Richard W Pogge ,D J Sullivan,I A Bond,D P Bennett,Koji Ohnishi ,M Dominik,I Soszyński,R Figuera Jaimes,D Suzuki,M Nagakane,A Udalski,C H Ling,M Hundertmark,Y Muraki,Andrew Gould ,Hisaaki Munakata ,To Saito ,K Horne

doi:10.3847/1538-4357/aaa295

Abstract

Abstract We present the analysis of the binary-microlensing event OGLE-2014-BLG-0289. The event light curve exhibits five very unusual peaks, four of which were produced by caustic crossings and the other by a cusp approach. It is found that the quintuple-peak features of the light curve provide tight constraints on the source trajectory, enabling us to precisely and accurately measure the microlensing parallax π E . Furthermore, the three resolved caustics allow us to measure the angular Einstein radius θ E . From the combination of π E and θ E , the physical lens parameters are uniquely determined. It is found that the lens is a binary composed of two M dwarfs with masses M 1 = 0.52 ± 0.04 M ⊙ and M 2 = 0.42 ± 0.03 M ⊙ separated in projection by a ⊥ = 6.4 ± 0.5 au . The lens is located in the disk with a distance of D L = 3.3 ± 0.3 kpc . The reason for the absence of a lensing signal in the Spitzer data is that the time of observation corresponds to the flat region of the light curve.

Highlights

Since commencing in the early 1990s (Udalski et al 1994; Alcock et al 1995; Aubourg et al 1995), massive surveys have detected numerous microlensing events
Measurements of annual microlens parallaxes are in many cases subject to large uncertainty both in precision and accuracy. It was pointed out by An & Gould (2001) that the chance to determine the lens mass by measuring both pE and qE is high for a subclass of binary lensing events with three wellmeasured peaks where two peaks are produced by caustic crossings and the other by a cusp approach
To show the variation of the lens positions and the resulting caustic due to lens-orbital effects, we present the caustics corresponding to four different times of the caustic crossings, it is difficult to see the variation due to the minor lens-orbital effects

Summary

Introduction

Since commencing in the early 1990s (Udalski et al 1994; Alcock et al 1995; Aubourg et al 1995), massive surveys have detected numerous microlensing events. Measurements of annual microlens parallaxes are in many cases subject to large uncertainty both in precision and accuracy It was pointed out by An & Gould (2001) that the chance to determine the lens mass by measuring both pE and qE is high for a subclass of binary lensing events with three wellmeasured peaks where two peaks are produced by caustic crossings and the other by a cusp approach. This is because the individual peaks provide tight constraints on the source trajectory, enabling one to measure the microlens parallax. The well-resolved multiple peaks enable us to measure the microlens parallax, leading to an accurate and precise measurement of the lens mass

Observation and Data

Light Curve Modeling

Is the Blend the Lens?

Discussion

Conclusion