A POSSIBLE BINARY SYSTEM OF A STELLAR REMNANT IN THE HIGH-MAGNIFICATION GRAVITATIONAL MICROLENSING EVENT OGLE-2007-BLG-514

N. Miyake*, A. Udalski, T. Sumi, D. P. Bennett, S. Dong, R. A. Street, J. Greenhill, I. A. Bond, A. Gould, M. Kubiak, M. K. Szymanski, G. Pietrzynski, I. Soszynski, K. Ulaczyk, L. Wyrzykowski, F. Abe, A. Fukui, K. Furusawa, S. Holderness, Y. ItowA. Korpela, C. H. Ling, K. Masuda, Y. Matsubara, Y. Muraki, T. Nagayama, K. Ohnishi, N. Rattenbury, To Saito, T. Sako, D. J. Sullivan, W. L. Sweatman, P. J. Tristram, P. C. M. Yock, W. Allen, G. W. Christie, D. L. DePoy, B. S. Gaudi, C. Han, C. -U. Lee, J. McCormick, B. Monard, T. Natusch, B. -G. Park, R. W. Pogge, A. Allan, M. Bode, D. M. Bramich, N. Clay, M. Dominik, K. D. Horne, N. Kains, C. Mottram, C. Snodgrass, I. Steele, Y. Tsapras, M. D. Albrow, V. Batista, J. P. Beaulieu, S. Brillant, M. Burgdorf, J. A. R. Caldwell, A. Cassan, A. Cole, K. H. Cook, Ch Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, P. Fouque, U. G. Jorgensen, S. Kane, D. Kubas, J. B. Marquette, R. Martin, J. Menzies, K. R. Pollard, K. C. Sahu, J. Wambsganss, A. Williams, M. Zub

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

We report the extremely high-magnification (A > 1000) binary microlensing event OGLE-2007-BLG-514. We obtained good coverage around the double peak structure in the light curve via follow-up observations from different observatories. The binary lens model that includes the effects of parallax (known orbital motion of the Earth) and orbital motion of the lens yields a binary lens mass ratio of q = 0.321 +/- 0.007 and a projected separation of s = 0.072 +/- 0.001 in units of the Einstein radius. The parallax parameters allow us to determine the lens distance D-L = 3.11 +/- 0.39 kpc and total mass M-L = 1.40 +/- 0.18 M-circle dot; this leads to the primary and secondary components having masses of M-1 = 1.06 +/- 0.13 M-circle dot and M-2 = 0.34 +/- 0.04 M-circle dot, respectively. The parallax model indicates that the binary lens system is likely constructed by the main-sequence stars. On the other hand, we used a Bayesian analysis to estimate probability distributions by the model that includes the effects of xallarap (possible orbital motion of the source around a companion) and parallax (q = 0.270 +/- 0.005, s = 0.083 +/- 0.001). The primary component of the binary lens is relatively massive, with M-1 = 0.9(-0.3)(+4.6) M-circle dot and it is at a distance of D-L = 2.6(-0.9)(+3.8) kpc. Given the secure mass ratio measurement, the companion mass is therefore M-2 = 0.2(-0.1)(+1.2) M-circle dot. The xallarap model implies that the primary lens is likely a stellar remnant, such as a white dwarf, a neutron star, or a black hole.

Original languageEnglish
Article number82
Number of pages12
JournalAstrophysical Journal
Volume752
Issue number2
DOIs
Publication statusPublished - 20 Jun 2012

Keywords

  • binaries: general
  • Galaxy: bulge
  • gravitational lensing: micro
  • GALACTIC BULGE
  • CHEMICAL EVOLUTION
  • LENSING EXPERIMENT
  • MASS-DISTRIBUTION
  • BLACK-HOLES
  • DWARF
  • PHOTOMETRY
  • PLANET
  • STARS
  • ATMOSPHERE

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