Difference Image Analysis of the OGLE-II Bulge Data. II. Microlensing Events

• Autorzy: Woźniak P. R. , Udalski A. , Szymański M. , Kubiak M. , Pietrzyński G. , Soszyński I. , Żebruń K.
• Języki publikacji: EN

Abstrakty

EN

We present a sample of microlensing events discovered in the Difference Image Analysis (DIA) of the OGLE-II images collected during three observing seasons, 1997-1999. 4424 light curves pass our criteria on the presence of a brightening episode on top of a constant baseline. Among those, 512 candidate microlensing events were selected visually. We designed an automated procedure, which unambiguously selects up to 237 best events. Including eight candidate events recovered by other means, a total of 520 light curves are presented in this work. In addition to microlensing events, the larger sample contains certain types of transients, but is also strongly contaminated by artifacts. All 4424 light curves in the weakly filtered group are available electronically, with the intent of showing the gray zone between microlensing events and variable stars, as well as artifacts, to some extent inevitable in massive data reductions. We welcome suggestions for improving the selection process before the full analysis of complete four seasons of the OGLE-II bulge data. Selection criteria for binary events can also be investigated with our extended sample.

Słowa kluczowe

EN

gravitational lensing; dark matter; galaxy: center; catalogs

• Wydawca: Copernicus Foundation for Polish Astronomy
• Czasopismo: Acta Astronomica
• Rocznik: 2001
• Tom: Vol. 51, No. 3
• Strony: 175--219
• Opis fizyczny: Bibliogr. 23 poz., rys., tab., wykr.

Twórcy

autor

Woźniak P. R.

• Princeton University Observatory, Princeton, NJ08544, USA
• Los Alamos National Laboratory, MS-D436, Los Alamos, NM 87545, USA

autor

Udalski A.

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

autor

Szymański M.

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

autor

Kubiak M.

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

autor

Pietrzyński G.

• Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
• Universidad de Concepción, Departamento de Fisica, Casilla, 160-C, Concepción, Chile

autor

Soszyński I.

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

autor

Żebruń K.

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

Bibliografia

• Afonso, C. et al. 1999, Astron. Astrophys., 344, L63.
• Alard, C., and Lupton, R.H. 1998, Astrophys. J., 503, 325.
• Alard, C. 2000, Astron. Astrophys. Suppl. Ser., 144, 363.
• Alcock, C. et al. 1997, Astrophys. J., 479, 119.
• Alcock, C. et al. 1999a, Astrophys. J., 521, 602.
• Alcock, C. et al. 1999b, Astrophys. J. Suppl. Ser., 124, 171.
• Alcock, C. et al. 2000a, Astrophys. J., 541, 270.
• Alcock, C. et al. 2000b, Astrophys. J., 541, 734.
• Bond, I.A. et al. 2001, MNRAS, submitted, astro-ph/0102184.
• Di Stefano, R. 2000, Astrophys. J., 541, 587.
• Eyer, L., and Woźniak, P. 2001, MNRAS, in press, astro-ph/0102027.
• Gould, A. 1995, Astrophys. J. Letters, 441, L21.
• Han, C., and Gould, A. 1995, Astrophys. J., 449, 521.
• Mao, S., and Paczyński, B. 1991, Astrophys. J. Letters, 374, L37.
• Paczyński, B. 1986, Astrophys. J., 304, 1.
• Paczyński, B. 1996, Ann. Rev. Astron. Astrophys, 34, 419.
• Popowski, P. et al. 2000, ASP Conf. Series, in press, "Microlensing 2000: A New Era ofMicrolensing Astrophysics", Ed. J.W. Menzies and P.D. Sackett, astro-ph/0005466.
• Tomaney, A.B., and Crotts, A.P. 1996, Astron. J., 112, 2872.
• Udalski, A., Szymański, M., Stanek, K.Z., Kałużny, J., Kubiak, M., Mateo, M., Krzemiński, W., Paczyński, B., and Venkat, R. 1994a, Acta Astron., 44, 165.
• Udalski, A., Szymański, M., Kałużny, J., Kubiak, M., Mateo, M., Krzemiński, W., Paczyński, B. 1994b, Acta Astron., 44, 227.
• Udalski, A., Kubiak, M., and Szymański, M. 1997, Acta Astron., 47, 319.
• Udalski, A., Żebruń, K., Szymański, M., Kubiak, M., Pietrzyński, G. Soszyński, I., and Woźniak, P.R. 2000, Acta Astron., 50, 1.
• Woźniak, P.R. 2000, Acta Astron., 50, 421.