Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source stars

J. Y. Choi, I. G. Shin, S. Y. Park, C. Han, A. Gould, T. Sumi, A. Udalski, J. P. Beaulieu, R. Street, M. Dominik, W. Allen, L. A. Almeida, M. Bos, G. W. Christie, D. L. Depoy, S. Dong, J. Drummond, A. Gal-Yam, B. S. Gaudi, C. B. Henderson & 131 others L. W. Hung, F. Jablonski, J. Janczak, C. U. Lee, F. Mallia, A. Maury, J. McCormick, D. McGregor, L. A G Monard, D. Moorhouse, J. A. Muñoz, T. Natusch, C. Nelson, B. G. Park, R. W. Pogge, T. G. Tg Tan, G. Thornley, J. C. Yee, F. Abe, E. Barnard, J. Baudry, D. P. Bennett, I. A. Bond, C. S. Botzler, M. Freeman, A. Fukui, K. Furusawa, F. Hayashi, J. B. Hearnshaw, S. Hosaka, Y. Itow, K. Kamiya, P. M. Kilmartin, S. Kobara, A. Korpela, W. Lin, C. H. Ling, S. Makita, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, M. Nagaya, K. Nishimoto, K. Ohnishi, T. Okumura, K. Omori, Y. C. Perrott, N. Rattenbury, To Saito, L. Skuljan, D. J. Sullivan, D. Suzuki, K. Suzuki, W. L. Sweatman, S. Takino, P. J. Tristram, K. Wada, P. C M Yock, M. K. Szymański, M. Kubiak, G. Pietrzyński, I. Soszyński, R. Poleski, K. Ulaczyk, Wyrzykowski, S. Kozłowski, P. Pietrukowicz, M. D. Albrow, E. Bachelet, V. Batista, C. S. Bennett, R. Bowens-Rubin, S. Brillant, A. Cassan, A. Cole, E. Corrales, Ch Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, P. Fouqué, J. Greenhill, S. R. Kane, J. Menzies, K. C. Sahu, J. Wambsganss, A. Williams, M. Zub, A. Allan, D. M. Bramich, P. Browne, N. Clay, S. Fraser, K. Horne, N. Kains, C. Mottram, C. Snodgrass, I. Steele, Y. Tsapras, Khalid Al-Subai, V. Bozza, M. J. Burgdorf, S. Calchi Novati, P. Dodds, S. Dreizler, F. Finet, T. Gerner, M. Glitrup, F. Grundahl, S. Hardis, K. Harpsoe, T. C. Hinse, M. Hundertmark, U. G. Jorgensen, E. Kerins, C. Liebig, G. Maier, L. Mancini, M. Mathiasen, M. T. Penny, S. Proft, S. Rahvar, D. Ricci, G. Scarpetta, S. Schäfer, F. Schönebeck, J. Skottfelt, J. Surdej, J. Southworth, F. Zimmer

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE- 2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/ MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of θE 0.08 mas combined with the short timescale of t E 2.7days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of 0.84 M is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio.

Original languageEnglish
Article number41
JournalAstrophysical Journal
Volume751
Issue number1
DOIs
Publication statusPublished - 20 May 2012

Fingerprint

gravitational lenses
magnification
lenses
stars
planet
limb
diagram
light curve
radii
timescale
planets
limb darkening
parallax
proper motion
exclusion
mass ratios
floating
confidence
brightness
diagrams

Keywords

  • Galaxy: bulge
  • gravitational lensing: micro

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source stars. / Choi, J. Y.; Shin, I. G.; Park, S. Y.; Han, C.; Gould, A.; Sumi, T.; Udalski, A.; Beaulieu, J. P.; Street, R.; Dominik, M.; Allen, W.; Almeida, L. A.; Bos, M.; Christie, G. W.; Depoy, D. L.; Dong, S.; Drummond, J.; Gal-Yam, A.; Gaudi, B. S.; Henderson, C. B.; Hung, L. W.; Jablonski, F.; Janczak, J.; Lee, C. U.; Mallia, F.; Maury, A.; McCormick, J.; McGregor, D.; Monard, L. A G; Moorhouse, D.; Muñoz, J. A.; Natusch, T.; Nelson, C.; Park, B. G.; Pogge, R. W.; Tg Tan, T. G.; Thornley, G.; Yee, J. C.; Abe, F.; Barnard, E.; Baudry, J.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Furusawa, K.; Hayashi, F.; Hearnshaw, J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.; Kilmartin, P. M.; Kobara, S.; Korpela, A.; Lin, W.; Ling, C. H.; Makita, S.; Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki, Y.; Nagaya, M.; Nishimoto, K.; Ohnishi, K.; Okumura, T.; Omori, K.; Perrott, Y. C.; Rattenbury, N.; Saito, To; Skuljan, L.; Sullivan, D. J.; Suzuki, D.; Suzuki, K.; Sweatman, W. L.; Takino, S.; Tristram, P. J.; Wada, K.; Yock, P. C M; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Poleski, R.; Ulaczyk, K.; Wyrzykowski; Kozłowski, S.; Pietrukowicz, P.; Albrow, M. D.; Bachelet, E.; Batista, V.; Bennett, C. S.; Bowens-Rubin, R.; Brillant, S.; Cassan, A.; Cole, A.; Corrales, E.; Coutures, Ch; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Greenhill, J.; Kane, S. R.; Menzies, J.; Sahu, K. C.; Wambsganss, J.; Williams, A.; Zub, M.; Allan, A.; Bramich, D. M.; Browne, P.; Clay, N.; Fraser, S.; Horne, K.; Kains, N.; Mottram, C.; Snodgrass, C.; Steele, I.; Tsapras, Y.; Al-Subai, Khalid; Bozza, V.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dreizler, S.; Finet, F.; Gerner, T.; Glitrup, M.; Grundahl, F.; Hardis, S.; Harpsoe, K.; Hinse, T. C.; Hundertmark, M.; Jorgensen, U. G.; Kerins, E.; Liebig, C.; Maier, G.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Proft, S.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Schäfer, S.; Schönebeck, F.; Skottfelt, J.; Surdej, J.; Southworth, J.; Zimmer, F.

In: Astrophysical Journal, Vol. 751, No. 1, 41, 20.05.2012.

Research output: Contribution to journalArticle

Choi, JY, Shin, IG, Park, SY, Han, C, Gould, A, Sumi, T, Udalski, A, Beaulieu, JP, Street, R, Dominik, M, Allen, W, Almeida, LA, Bos, M, Christie, GW, Depoy, DL, Dong, S, Drummond, J, Gal-Yam, A, Gaudi, BS, Henderson, CB, Hung, LW, Jablonski, F, Janczak, J, Lee, CU, Mallia, F, Maury, A, McCormick, J, McGregor, D, Monard, LAG, Moorhouse, D, Muñoz, JA, Natusch, T, Nelson, C, Park, BG, Pogge, RW, Tg Tan, TG, Thornley, G, Yee, JC, Abe, F, Barnard, E, Baudry, J, Bennett, DP, Bond, IA, Botzler, CS, Freeman, M, Fukui, A, Furusawa, K, Hayashi, F, Hearnshaw, JB, Hosaka, S, Itow, Y, Kamiya, K, Kilmartin, PM, Kobara, S, Korpela, A, Lin, W, Ling, CH, Makita, S, Masuda, K, Matsubara, Y, Miyake, N, Muraki, Y, Nagaya, M, Nishimoto, K, Ohnishi, K, Okumura, T, Omori, K, Perrott, YC, Rattenbury, N, Saito, T, Skuljan, L, Sullivan, DJ, Suzuki, D, Suzuki, K, Sweatman, WL, Takino, S, Tristram, PJ, Wada, K, Yock, PCM, Szymański, MK, Kubiak, M, Pietrzyński, G, Soszyński, I, Poleski, R, Ulaczyk, K, Wyrzykowski, Kozłowski, S, Pietrukowicz, P, Albrow, MD, Bachelet, E, Batista, V, Bennett, CS, Bowens-Rubin, R, Brillant, S, Cassan, A, Cole, A, Corrales, E, Coutures, C, Dieters, S, Dominis Prester, D, Donatowicz, J, Fouqué, P, Greenhill, J, Kane, SR, Menzies, J, Sahu, KC, Wambsganss, J, Williams, A, Zub, M, Allan, A, Bramich, DM, Browne, P, Clay, N, Fraser, S, Horne, K, Kains, N, Mottram, C, Snodgrass, C, Steele, I, Tsapras, Y, Al-Subai, K, Bozza, V, Burgdorf, MJ, Calchi Novati, S, Dodds, P, Dreizler, S, Finet, F, Gerner, T, Glitrup, M, Grundahl, F, Hardis, S, Harpsoe, K, Hinse, TC, Hundertmark, M, Jorgensen, UG, Kerins, E, Liebig, C, Maier, G, Mancini, L, Mathiasen, M, Penny, MT, Proft, S, Rahvar, S, Ricci, D, Scarpetta, G, Schäfer, S, Schönebeck, F, Skottfelt, J, Surdej, J, Southworth, J & Zimmer, F 2012, 'Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source stars', Astrophysical Journal, vol. 751, no. 1, 41. https://doi.org/10.1088/0004-637X/751/1/41
Choi, J. Y. ; Shin, I. G. ; Park, S. Y. ; Han, C. ; Gould, A. ; Sumi, T. ; Udalski, A. ; Beaulieu, J. P. ; Street, R. ; Dominik, M. ; Allen, W. ; Almeida, L. A. ; Bos, M. ; Christie, G. W. ; Depoy, D. L. ; Dong, S. ; Drummond, J. ; Gal-Yam, A. ; Gaudi, B. S. ; Henderson, C. B. ; Hung, L. W. ; Jablonski, F. ; Janczak, J. ; Lee, C. U. ; Mallia, F. ; Maury, A. ; McCormick, J. ; McGregor, D. ; Monard, L. A G ; Moorhouse, D. ; Muñoz, J. A. ; Natusch, T. ; Nelson, C. ; Park, B. G. ; Pogge, R. W. ; Tg Tan, T. G. ; Thornley, G. ; Yee, J. C. ; Abe, F. ; Barnard, E. ; Baudry, J. ; Bennett, D. P. ; Bond, I. A. ; Botzler, C. S. ; Freeman, M. ; Fukui, A. ; Furusawa, K. ; Hayashi, F. ; Hearnshaw, J. B. ; Hosaka, S. ; Itow, Y. ; Kamiya, K. ; Kilmartin, P. M. ; Kobara, S. ; Korpela, A. ; Lin, W. ; Ling, C. H. ; Makita, S. ; Masuda, K. ; Matsubara, Y. ; Miyake, N. ; Muraki, Y. ; Nagaya, M. ; Nishimoto, K. ; Ohnishi, K. ; Okumura, T. ; Omori, K. ; Perrott, Y. C. ; Rattenbury, N. ; Saito, To ; Skuljan, L. ; Sullivan, D. J. ; Suzuki, D. ; Suzuki, K. ; Sweatman, W. L. ; Takino, S. ; Tristram, P. J. ; Wada, K. ; Yock, P. C M ; Szymański, M. K. ; Kubiak, M. ; Pietrzyński, G. ; Soszyński, I. ; Poleski, R. ; Ulaczyk, K. ; Wyrzykowski ; Kozłowski, S. ; Pietrukowicz, P. ; Albrow, M. D. ; Bachelet, E. ; Batista, V. ; Bennett, C. S. ; Bowens-Rubin, R. ; Brillant, S. ; Cassan, A. ; Cole, A. ; Corrales, E. ; Coutures, Ch ; Dieters, S. ; Dominis Prester, D. ; Donatowicz, J. ; Fouqué, P. ; Greenhill, J. ; Kane, S. R. ; Menzies, J. ; Sahu, K. C. ; Wambsganss, J. ; Williams, A. ; Zub, M. ; Allan, A. ; Bramich, D. M. ; Browne, P. ; Clay, N. ; Fraser, S. ; Horne, K. ; Kains, N. ; Mottram, C. ; Snodgrass, C. ; Steele, I. ; Tsapras, Y. ; Al-Subai, Khalid ; Bozza, V. ; Burgdorf, M. J. ; Calchi Novati, S. ; Dodds, P. ; Dreizler, S. ; Finet, F. ; Gerner, T. ; Glitrup, M. ; Grundahl, F. ; Hardis, S. ; Harpsoe, K. ; Hinse, T. C. ; Hundertmark, M. ; Jorgensen, U. G. ; Kerins, E. ; Liebig, C. ; Maier, G. ; Mancini, L. ; Mathiasen, M. ; Penny, M. T. ; Proft, S. ; Rahvar, S. ; Ricci, D. ; Scarpetta, G. ; Schäfer, S. ; Schönebeck, F. ; Skottfelt, J. ; Surdej, J. ; Southworth, J. ; Zimmer, F. / Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source stars. In: Astrophysical Journal. 2012 ; Vol. 751, No. 1.
@article{faa0b2769a2d48b3a36e94740e3da95e,
title = "Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source stars",
abstract = "We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE- 2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/ MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of θE 0.08 mas combined with the short timescale of t E 2.7days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of 0.84 M ⊙ is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio.",
keywords = "Galaxy: bulge, gravitational lensing: micro",
author = "Choi, {J. Y.} and Shin, {I. G.} and Park, {S. Y.} and C. Han and A. Gould and T. Sumi and A. Udalski and Beaulieu, {J. P.} and R. Street and M. Dominik and W. Allen and Almeida, {L. A.} and M. Bos and Christie, {G. W.} and Depoy, {D. L.} and S. Dong and J. Drummond and A. Gal-Yam and Gaudi, {B. S.} and Henderson, {C. B.} and Hung, {L. W.} and F. Jablonski and J. Janczak and Lee, {C. U.} and F. Mallia and A. Maury and J. McCormick and D. McGregor and Monard, {L. A G} and D. Moorhouse and Mu{\~n}oz, {J. A.} and T. Natusch and C. Nelson and Park, {B. G.} and Pogge, {R. W.} and {Tg Tan}, {T. G.} and G. Thornley and Yee, {J. C.} and F. Abe and E. Barnard and J. Baudry and Bennett, {D. P.} and Bond, {I. A.} and Botzler, {C. S.} and M. Freeman and A. Fukui and K. Furusawa and F. Hayashi and Hearnshaw, {J. B.} and S. Hosaka and Y. Itow and K. Kamiya and Kilmartin, {P. M.} and S. Kobara and A. Korpela and W. Lin and Ling, {C. H.} and S. Makita and K. Masuda and Y. Matsubara and N. Miyake and Y. Muraki and M. Nagaya and K. Nishimoto and K. Ohnishi and T. Okumura and K. Omori and Perrott, {Y. C.} and N. Rattenbury and To Saito and L. Skuljan and Sullivan, {D. J.} and D. Suzuki and K. Suzuki and Sweatman, {W. L.} and S. Takino and Tristram, {P. J.} and K. Wada and Yock, {P. C M} and Szymański, {M. K.} and M. Kubiak and G. Pietrzyński and I. Soszyński and R. Poleski and K. Ulaczyk and Wyrzykowski and S. Kozłowski and P. Pietrukowicz and Albrow, {M. D.} and E. Bachelet and V. Batista and Bennett, {C. S.} and R. Bowens-Rubin and S. Brillant and A. Cassan and A. Cole and E. Corrales and Ch Coutures and S. Dieters and {Dominis Prester}, D. and J. Donatowicz and P. Fouqu{\'e} and J. Greenhill and Kane, {S. R.} and J. Menzies and Sahu, {K. C.} and J. Wambsganss and A. Williams and M. Zub and A. Allan and Bramich, {D. M.} and P. Browne and N. Clay and S. Fraser and K. Horne and N. Kains and C. Mottram and C. Snodgrass and I. Steele and Y. Tsapras and Khalid Al-Subai and V. Bozza and Burgdorf, {M. J.} and {Calchi Novati}, S. and P. Dodds and S. Dreizler and F. Finet and T. Gerner and M. Glitrup and F. Grundahl and S. Hardis and K. Harpsoe and Hinse, {T. C.} and M. Hundertmark and Jorgensen, {U. G.} and E. Kerins and C. Liebig and G. Maier and L. Mancini and M. Mathiasen and Penny, {M. T.} and S. Proft and S. Rahvar and D. Ricci and G. Scarpetta and S. Sch{\"a}fer and F. Sch{\"o}nebeck and J. Skottfelt and J. Surdej and J. Southworth and F. Zimmer",
year = "2012",
month = "5",
day = "20",
doi = "10.1088/0004-637X/751/1/41",
language = "English",
volume = "751",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source stars

AU - Choi, J. Y.

AU - Shin, I. G.

AU - Park, S. Y.

AU - Han, C.

AU - Gould, A.

AU - Sumi, T.

AU - Udalski, A.

AU - Beaulieu, J. P.

AU - Street, R.

AU - Dominik, M.

AU - Allen, W.

AU - Almeida, L. A.

AU - Bos, M.

AU - Christie, G. W.

AU - Depoy, D. L.

AU - Dong, S.

AU - Drummond, J.

AU - Gal-Yam, A.

AU - Gaudi, B. S.

AU - Henderson, C. B.

AU - Hung, L. W.

AU - Jablonski, F.

AU - Janczak, J.

AU - Lee, C. U.

AU - Mallia, F.

AU - Maury, A.

AU - McCormick, J.

AU - McGregor, D.

AU - Monard, L. A G

AU - Moorhouse, D.

AU - Muñoz, J. A.

AU - Natusch, T.

AU - Nelson, C.

AU - Park, B. G.

AU - Pogge, R. W.

AU - Tg Tan, T. G.

AU - Thornley, G.

AU - Yee, J. C.

AU - Abe, F.

AU - Barnard, E.

AU - Baudry, J.

AU - Bennett, D. P.

AU - Bond, I. A.

AU - Botzler, C. S.

AU - Freeman, M.

AU - Fukui, A.

AU - Furusawa, K.

AU - Hayashi, F.

AU - Hearnshaw, J. B.

AU - Hosaka, S.

AU - Itow, Y.

AU - Kamiya, K.

AU - Kilmartin, P. M.

AU - Kobara, S.

AU - Korpela, A.

AU - Lin, W.

AU - Ling, C. H.

AU - Makita, S.

AU - Masuda, K.

AU - Matsubara, Y.

AU - Miyake, N.

AU - Muraki, Y.

AU - Nagaya, M.

AU - Nishimoto, K.

AU - Ohnishi, K.

AU - Okumura, T.

AU - Omori, K.

AU - Perrott, Y. C.

AU - Rattenbury, N.

AU - Saito, To

AU - Skuljan, L.

AU - Sullivan, D. J.

AU - Suzuki, D.

AU - Suzuki, K.

AU - Sweatman, W. L.

AU - Takino, S.

AU - Tristram, P. J.

AU - Wada, K.

AU - Yock, P. C M

AU - Szymański, M. K.

AU - Kubiak, M.

AU - Pietrzyński, G.

AU - Soszyński, I.

AU - Poleski, R.

AU - Ulaczyk, K.

AU - Wyrzykowski,

AU - Kozłowski, S.

AU - Pietrukowicz, P.

AU - Albrow, M. D.

AU - Bachelet, E.

AU - Batista, V.

AU - Bennett, C. S.

AU - Bowens-Rubin, R.

AU - Brillant, S.

AU - Cassan, A.

AU - Cole, A.

AU - Corrales, E.

AU - Coutures, Ch

AU - Dieters, S.

AU - Dominis Prester, D.

AU - Donatowicz, J.

AU - Fouqué, P.

AU - Greenhill, J.

AU - Kane, S. R.

AU - Menzies, J.

AU - Sahu, K. C.

AU - Wambsganss, J.

AU - Williams, A.

AU - Zub, M.

AU - Allan, A.

AU - Bramich, D. M.

AU - Browne, P.

AU - Clay, N.

AU - Fraser, S.

AU - Horne, K.

AU - Kains, N.

AU - Mottram, C.

AU - Snodgrass, C.

AU - Steele, I.

AU - Tsapras, Y.

AU - Al-Subai, Khalid

AU - Bozza, V.

AU - Burgdorf, M. J.

AU - Calchi Novati, S.

AU - Dodds, P.

AU - Dreizler, S.

AU - Finet, F.

AU - Gerner, T.

AU - Glitrup, M.

AU - Grundahl, F.

AU - Hardis, S.

AU - Harpsoe, K.

AU - Hinse, T. C.

AU - Hundertmark, M.

AU - Jorgensen, U. G.

AU - Kerins, E.

AU - Liebig, C.

AU - Maier, G.

AU - Mancini, L.

AU - Mathiasen, M.

AU - Penny, M. T.

AU - Proft, S.

AU - Rahvar, S.

AU - Ricci, D.

AU - Scarpetta, G.

AU - Schäfer, S.

AU - Schönebeck, F.

AU - Skottfelt, J.

AU - Surdej, J.

AU - Southworth, J.

AU - Zimmer, F.

PY - 2012/5/20

Y1 - 2012/5/20

N2 - We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE- 2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/ MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of θE 0.08 mas combined with the short timescale of t E 2.7days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of 0.84 M ⊙ is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio.

AB - We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE- 2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/ MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of θE 0.08 mas combined with the short timescale of t E 2.7days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of 0.84 M ⊙ is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio.

KW - Galaxy: bulge

KW - gravitational lensing: micro

UR - http://www.scopus.com/inward/record.url?scp=84860768882&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84860768882&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/751/1/41

DO - 10.1088/0004-637X/751/1/41

M3 - Article

VL - 751

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 41

ER -