Binary Lenses in OGLE-II 1997-1999 Database. A Preliminary Study

• Autorzy: Jaroszyński M.
• Języki publikacji: EN

Abstrakty

EN

We present 18 binary lens candidates from OGLE-II database for seasons 1997-1999. The candidates have been selected by visual light curves inspection from the subsample of strong transient events; the same procedure gives 215 single lens candidates. Among the double lenses there are 12 cases interpreted as caustic crossing events. We compare the mass ratio and separation distributions obtained for binary lenses with the predictions based on stellar double systems observations. We take into account the selection bias, which causes over-representation of binary lenses of similar mass and separation close to the Einstein radius. There is no strong discrepancy between the expected and observed distributions of the mass ratio or the binary separations. We find one or two cases of binary lens candidates, SC20_1793 and SC20_3525, with extreme mass ratios, which may suggest presence of planets or brown dwarf companions. Unfortunately, neither case is very strong, as alternative solutions provide fits to the data which are only unsubstantially worse. Binary lenses provide a modest contribution to the overall optical depth to microlensing.

Słowa kluczowe

EN

gravitational lensing; galaxy: center; galaxy: structure

• Wydawca: Copernicus Foundation for Polish Astronomy
• Czasopismo: Acta Astronomica
• Rocznik: 2002
• Tom: Vol. 52, No. 1
• Strony: 39--60
• Opis fizyczny: Bibliogr. 27 poz., tab., wykr.

Twórcy

autor

Jaroszyński M.

• Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

Bibliografia

• Abt, H.A. 1983, Ann. Rev. Astron. Astrophys., 21, 343.
• Alard, C. 2000, Astron. Astrophys. Suppl. Ser., 144, 363.
• Alard, C., and Lupton, R.H. 1998, Astrophys. J., 503, 325.
• Albrow, M.D., et al. 1999a, Astrophys. J., 512, 672.
• Albrow, M.D., et al. 1999b, Astrophys. J., 522, 1011.
• Albrow, M.D., et al. 1999c, Astrophys. J., 522, 1022.
• Alcock, C., et al. 2000, Astrophys. J., 541, 270.
• An, J.H., et al. 2001, Astrophys. J..submitted, astro-ph/0110095
• Blandford, R.D., and Narayan, R. 1992, Ann. Rev. Astron. Astrophys., 30, 311.
• DiStefano, R., and Mao, S. 1996, Astrophys. J., 457, 93.
• Dominik, M. 1998, Astron. Astrophys., 333, L79.
• Dominik, M. 1999, Astron. Astrophys., 341, 943.
• Jaroszy´nski, M., and Mao, S. 2001, MNRAS, 325, 1546.
• Mao, S., and DiStefano, R. 1995, Astrophys. J., 440, 22.
• Mao, S., and Loeb, A. 2001, Astrophys. J. Letters, 547, L97.
• Mao, S., and Paczyński, B. 1991, Astrophys. J. Letters, 374, L37.
• Paczy´nski, B. 1996, Ann. Rev. Astron. Astrophys., 34, 419.
• Press W.H., Teukolsky S.A., Vetterling W.T., and Flannery B.P. 1992, in: “Numerical Recipes in Fortran” (NY: CUP).
• Schneider, P., Ehlers, J., and Falco, E.E. 1992, “Gravitational Lenses”, Springer, Berlin.
• Schneider, P., and Weiss, A. 1986, Astron. Astrophys., 164, 237.
• Trimble, V. 1990, MNRAS, 242, 79.
• Udalski, A. et al. 1994a, Astrophys. J. Letters, 436, L103.
• Udalski, A., Szymański, M., Kałużny, J., Kubiak, M., Mateo, M., Krzemiński, W., and Paczyński, B. 1994b, Acta Astron., 44, 227.
• Udalski, A., Żebruń, K., Szymański, M., Kubiak, M., Pietrzyński, G., Soszyński, I., and Woźniak, P. 2000, Acta Astron., 50, 1.
• Woźniak, P.R. 2000, Acta Astron., 50, 421.
• Woźniak, P.R., and Paczyński, B. 1997, Astrophys. J., 487, 55.
• Woźniak, P.R.,Udalski, A., Szymański, M., Kubiak, M., Pietrzyński, G., Soszyński, I., and Żebruń, K. 2001, Acta Astron., 51, 175.