SPITZER MICROLENS MEASUREMENT of A MASSIVE REMNANT in A WELL-SEPARATED BINARY

Y. Shvartzvald, A. Udalski, A. Gould, C. Han, V. Bozza, M. Friedmann, M. Hundertmark, C. Beichman, G. Bryden, S. Calchi Novati, S. Carey, M. Fausnaugh, B. S. Gaudi, C. B. Henderson, T. Kerr, R. W. Pogge, W. Varricatt, B. Wibking, J. C. Yee, W. ZhuR. Poleski, M. Pawlak, M. K. Szymański, J. Skowron, P. Mróz, S. Kozłowski, [No Value] Wyrzykowski, P. Pietrukowicz, G. Pietrzyński, I. Soszyński, K. Ulaczyk, J. Y. Choi, H. Park, Y. K. Jung, I. G. Shin, M. D. Albrow, B. G. Park, S. L. Kim, C. U. Lee, S. M. Cha, D. J. Kim, Y. Lee, D. Maoz, S. Kaspi, R. A. Street, Y. Tsapras, E. Bachelet, M. Dominik, D. M. Bramich, Keith Horne, C. Snodgrass, I. A. Steele, J. Menzies, R. Figuera Jaimes, J. Wambsganss, R. Schmidt, A. Cassan, C. Ranc, S. Mao, Subo Dong, G. D'Ago, G. Scarpetta, P. Verma, U. G. Jørgensen, E. Kerins, J. Skottfelt

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Abstract

We report the detection and mass measurement of a binary lens OGLE-2015-BLG-1285La,b, with the more massive component having M1 > 1.35 Mo (80% probability). A main-sequence star in this mass range is ruled out by limits on blue light, meaning that a primary in this mass range must be a neutron star (NS) or black hole (BH). The system has a projected separation r = 6.1 ± 0.4 AU and lies in the Galactic bulge. These measurements are based on the "microlens parallax" effect, i.e., comparing the microlensing light curve as seen from Spitzer, which lay at 1.25 AU projected from Earth, to the light curves from four ground-based surveys, three in the optical and one in the near-infrared. Future adaptive optics imaging of the companion by 30 m class telescopes will yield a much more accurate measurement of the primary mass. This discovery both opens the path and defines the challenges to detecting and characterizing BHs and NSs in wide binaries, with either dark or luminous companions. In particular, we discuss lessons that can be applied to future Spitzer and Kepler K2 microlensing parallax observations.

Original languageEnglish
Article number111
JournalAstrophysical Journal
Volume814
Issue number2
DOIs
Publication statusPublished - 1 Dec 2015

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Keywords

  • binaries: general
  • black hole physics
  • Galaxy: bulge
  • gravitational lensing: micro
  • stars: neutron

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Shvartzvald, Y., Udalski, A., Gould, A., Han, C., Bozza, V., Friedmann, M., Hundertmark, M., Beichman, C., Bryden, G., Novati, S. C., Carey, S., Fausnaugh, M., Gaudi, B. S., Henderson, C. B., Kerr, T., Pogge, R. W., Varricatt, W., Wibking, B., Yee, J. C., ... Skottfelt, J. (2015). SPITZER MICROLENS MEASUREMENT of A MASSIVE REMNANT in A WELL-SEPARATED BINARY. Astrophysical Journal, 814(2), [111]. https://doi.org/10.1088/0004-637X/814/2/111