A new type of ambiguity in the planet and binary interpretations of central perturbations of high-magnification gravitational microlensing events

J. Y. Choi, I. G. Shin, C. Han, A. Udalski, T. Sumi, A. Gould, V. Bozza, M. Dominik, P. Fouqué, K. Horne, M. K. Szymański, M. Kubiak, I. Soszyński, G. Pietrzyński, R. Poleski, K. Ulaczyk, P. Pietrukowicz, S. Kozłowski, J. Skowron, Wyrzykowski & 100 others F. Abe, D. P. Bennett, I. A. Bond, C. S. Botzler, P. Chote, M. Freeman, A. Fukui, K. Furusawa, Y. Itow, S. Kobara, C. H. Ling, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, K. Ohmori, K. Ohnishi, N. J. Rattenbury, To Saito, D. J. Sullivan, D. Suzuki, K. Suzuki, W. L. Sweatman, S. Takino, P. J. Tristram, K. Wada, P. C M Yock, D. M. Bramich, C. Snodgrass, I. A. Steele, R. A. Street, Y. Tsapras, Khalid Al-Subai, P. Browne, M. J. Burgdorf, S. Calchi Novati, P. Dodds, S. Dreizler, X. S. Fang, F. Grundahl, C. H. Gu, S. Hardis, K. Harpsoe, T. C. Hinse, A. Hornstrup, M. Hundertmark, J. Jessen-Hansen, U. G. Jorgensen, N. Kains, E. Kerins, C. Liebig, M. Lund, M. Lunkkvist, L. Mancini, M. Mathiasen, M. T. Penny, S. Rahvar, D. Ricci, G. Scarpetta, J. Skottfelt, J. Southworth, J. Surdej, J. Tregloan-Reed, J. Wambsganss, O. Wertz, L. A. Almeida, V. Batista, G. Christie, D. L. Depoy, Subo Dong, B. S. Gaudi, C. Henderson, F. Jablonski, C. U. Lee, J. McCormick, D. McGregor, D. Moorhouse, T. Natusch, H. Ngan, R. W. Pogge, T. G. Tan, G. Thornley, J. C. Yee, M. D. Albrow, E. Bachelet, J. P. Beaulieu, S. Brillant, A. Cassan, A. A. Cole, E. Corrales, C. Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, J. Greenhill, D. Kubas, J. B. Marquette, J. W. Menzies, K. C. Sahu, M. Zub

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

High-magnification microlensing events provide an important channel to detect planets. Perturbations near the peak of a high-magnification event can be produced either by a planet or a binary companion. It is known that central perturbations induced by both types of companions can be generally distinguished due to the essentially different magnification pattern around caustics. In this paper, we present a case of central perturbations for which it is difficult to distinguish the planetary and binary interpretations. The peak of a lensing light curve affected by this perturbation appears to be blunt and flat. For a planetary case, this perturbation occurs when the source trajectory passes the negative perturbation region behind the back end of an arrowhead-shaped central caustic. For a binary case, a similar perturbation occurs for a source trajectory passing through the negative perturbation region between two cusps of an astroid-shaped caustic. We demonstrate the degeneracy for two high-magnification events of OGLE-2011-BLG-0526 and OGLE-2011-BLG-0950/MOA-2011- BLG-336. For OGLE-2011-BLG-0526, the χ2 difference between the planetary and binary model is 3, implying that the degeneracy is very severe. For OGLE-2011-BLG-0950/MOA-2011-BLG-336, the stellar binary model is formally excluded with Δχ2 105 and the planetary model is preferred. However, it is difficult to claim a planet discovery because systematic residuals of data from the planetary model are larger than the difference between the planetary and binary models. Considering that two events observed during a single season suffer from such a degeneracy, it is expected that central perturbations experiencing this type of degeneracy is common.

Original languageEnglish
Article number48
JournalAstrophysical Journal
Volume756
Issue number1
DOIs
Publication statusPublished - 24 Aug 2012

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magnification
ambiguity
planets
planet
perturbation
alkalies
trajectory
trajectories
cusps
light curve

Keywords

  • Galaxy: bulge
  • gravitational lensing: micro

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

A new type of ambiguity in the planet and binary interpretations of central perturbations of high-magnification gravitational microlensing events. / Choi, J. Y.; Shin, I. G.; Han, C.; Udalski, A.; Sumi, T.; Gould, A.; Bozza, V.; Dominik, M.; Fouqué, P.; Horne, K.; Szymański, M. K.; Kubiak, M.; Soszyński, I.; Pietrzyński, G.; Poleski, R.; Ulaczyk, K.; Pietrukowicz, P.; Kozłowski, S.; Skowron, J.; Wyrzykowski; Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Chote, P.; Freeman, M.; Fukui, A.; Furusawa, K.; Itow, Y.; Kobara, S.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki, Y.; Ohmori, K.; Ohnishi, K.; Rattenbury, N. J.; Saito, To; Sullivan, D. J.; Suzuki, D.; Suzuki, K.; Sweatman, W. L.; Takino, S.; Tristram, P. J.; Wada, K.; Yock, P. C M; Bramich, D. M.; Snodgrass, C.; Steele, I. A.; Street, R. A.; Tsapras, Y.; Al-Subai, Khalid; Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dreizler, S.; Fang, X. S.; Grundahl, F.; Gu, C. H.; Hardis, S.; Harpsoe, K.; Hinse, T. C.; Hornstrup, A.; Hundertmark, M.; Jessen-Hansen, J.; Jorgensen, U. G.; Kains, N.; Kerins, E.; Liebig, C.; Lund, M.; Lunkkvist, M.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Surdej, J.; Tregloan-Reed, J.; Wambsganss, J.; Wertz, O.; Almeida, L. A.; Batista, V.; Christie, G.; Depoy, D. L.; Dong, Subo; Gaudi, B. S.; Henderson, C.; Jablonski, F.; Lee, C. U.; McCormick, J.; McGregor, D.; Moorhouse, D.; Natusch, T.; Ngan, H.; Pogge, R. W.; Tan, T. G.; Thornley, G.; Yee, J. C.; Albrow, M. D.; Bachelet, E.; Beaulieu, J. P.; Brillant, S.; Cassan, A.; Cole, A. A.; Corrales, E.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Greenhill, J.; Kubas, D.; Marquette, J. B.; Menzies, J. W.; Sahu, K. C.; Zub, M.

In: Astrophysical Journal, Vol. 756, No. 1, 48, 24.08.2012.

Research output: Contribution to journalArticle

Choi, JY, Shin, IG, Han, C, Udalski, A, Sumi, T, Gould, A, Bozza, V, Dominik, M, Fouqué, P, Horne, K, Szymański, MK, Kubiak, M, Soszyński, I, Pietrzyński, G, Poleski, R, Ulaczyk, K, Pietrukowicz, P, Kozłowski, S, Skowron, J, Wyrzykowski, Abe, F, Bennett, DP, Bond, IA, Botzler, CS, Chote, P, Freeman, M, Fukui, A, Furusawa, K, Itow, Y, Kobara, S, Ling, CH, Masuda, K, Matsubara, Y, Miyake, N, Muraki, Y, Ohmori, K, Ohnishi, K, Rattenbury, NJ, Saito, T, Sullivan, DJ, Suzuki, D, Suzuki, K, Sweatman, WL, Takino, S, Tristram, PJ, Wada, K, Yock, PCM, Bramich, DM, Snodgrass, C, Steele, IA, Street, RA, Tsapras, Y, Al-Subai, K, Browne, P, Burgdorf, MJ, Calchi Novati, S, Dodds, P, Dreizler, S, Fang, XS, Grundahl, F, Gu, CH, Hardis, S, Harpsoe, K, Hinse, TC, Hornstrup, A, Hundertmark, M, Jessen-Hansen, J, Jorgensen, UG, Kains, N, Kerins, E, Liebig, C, Lund, M, Lunkkvist, M, Mancini, L, Mathiasen, M, Penny, MT, Rahvar, S, Ricci, D, Scarpetta, G, Skottfelt, J, Southworth, J, Surdej, J, Tregloan-Reed, J, Wambsganss, J, Wertz, O, Almeida, LA, Batista, V, Christie, G, Depoy, DL, Dong, S, Gaudi, BS, Henderson, C, Jablonski, F, Lee, CU, McCormick, J, McGregor, D, Moorhouse, D, Natusch, T, Ngan, H, Pogge, RW, Tan, TG, Thornley, G, Yee, JC, Albrow, MD, Bachelet, E, Beaulieu, JP, Brillant, S, Cassan, A, Cole, AA, Corrales, E, Coutures, C, Dieters, S, Dominis Prester, D, Donatowicz, J, Greenhill, J, Kubas, D, Marquette, JB, Menzies, JW, Sahu, KC & Zub, M 2012, 'A new type of ambiguity in the planet and binary interpretations of central perturbations of high-magnification gravitational microlensing events', Astrophysical Journal, vol. 756, no. 1, 48. https://doi.org/10.1088/0004-637X/756/1/48
Choi, J. Y. ; Shin, I. G. ; Han, C. ; Udalski, A. ; Sumi, T. ; Gould, A. ; Bozza, V. ; Dominik, M. ; Fouqué, P. ; Horne, K. ; Szymański, M. K. ; Kubiak, M. ; Soszyński, I. ; Pietrzyński, G. ; Poleski, R. ; Ulaczyk, K. ; Pietrukowicz, P. ; Kozłowski, S. ; Skowron, J. ; Wyrzykowski ; Abe, F. ; Bennett, D. P. ; Bond, I. A. ; Botzler, C. S. ; Chote, P. ; Freeman, M. ; Fukui, A. ; Furusawa, K. ; Itow, Y. ; Kobara, S. ; Ling, C. H. ; Masuda, K. ; Matsubara, Y. ; Miyake, N. ; Muraki, Y. ; Ohmori, K. ; Ohnishi, K. ; Rattenbury, N. J. ; Saito, To ; Sullivan, D. J. ; Suzuki, D. ; Suzuki, K. ; Sweatman, W. L. ; Takino, S. ; Tristram, P. J. ; Wada, K. ; Yock, P. C M ; Bramich, D. M. ; Snodgrass, C. ; Steele, I. A. ; Street, R. A. ; Tsapras, Y. ; Al-Subai, Khalid ; Browne, P. ; Burgdorf, M. J. ; Calchi Novati, S. ; Dodds, P. ; Dreizler, S. ; Fang, X. S. ; Grundahl, F. ; Gu, C. H. ; Hardis, S. ; Harpsoe, K. ; Hinse, T. C. ; Hornstrup, A. ; Hundertmark, M. ; Jessen-Hansen, J. ; Jorgensen, U. G. ; Kains, N. ; Kerins, E. ; Liebig, C. ; Lund, M. ; Lunkkvist, M. ; Mancini, L. ; Mathiasen, M. ; Penny, M. T. ; Rahvar, S. ; Ricci, D. ; Scarpetta, G. ; Skottfelt, J. ; Southworth, J. ; Surdej, J. ; Tregloan-Reed, J. ; Wambsganss, J. ; Wertz, O. ; Almeida, L. A. ; Batista, V. ; Christie, G. ; Depoy, D. L. ; Dong, Subo ; Gaudi, B. S. ; Henderson, C. ; Jablonski, F. ; Lee, C. U. ; McCormick, J. ; McGregor, D. ; Moorhouse, D. ; Natusch, T. ; Ngan, H. ; Pogge, R. W. ; Tan, T. G. ; Thornley, G. ; Yee, J. C. ; Albrow, M. D. ; Bachelet, E. ; Beaulieu, J. P. ; Brillant, S. ; Cassan, A. ; Cole, A. A. ; Corrales, E. ; Coutures, C. ; Dieters, S. ; Dominis Prester, D. ; Donatowicz, J. ; Greenhill, J. ; Kubas, D. ; Marquette, J. B. ; Menzies, J. W. ; Sahu, K. C. ; Zub, M. / A new type of ambiguity in the planet and binary interpretations of central perturbations of high-magnification gravitational microlensing events. In: Astrophysical Journal. 2012 ; Vol. 756, No. 1.
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title = "A new type of ambiguity in the planet and binary interpretations of central perturbations of high-magnification gravitational microlensing events",
abstract = "High-magnification microlensing events provide an important channel to detect planets. Perturbations near the peak of a high-magnification event can be produced either by a planet or a binary companion. It is known that central perturbations induced by both types of companions can be generally distinguished due to the essentially different magnification pattern around caustics. In this paper, we present a case of central perturbations for which it is difficult to distinguish the planetary and binary interpretations. The peak of a lensing light curve affected by this perturbation appears to be blunt and flat. For a planetary case, this perturbation occurs when the source trajectory passes the negative perturbation region behind the back end of an arrowhead-shaped central caustic. For a binary case, a similar perturbation occurs for a source trajectory passing through the negative perturbation region between two cusps of an astroid-shaped caustic. We demonstrate the degeneracy for two high-magnification events of OGLE-2011-BLG-0526 and OGLE-2011-BLG-0950/MOA-2011- BLG-336. For OGLE-2011-BLG-0526, the χ2 difference between the planetary and binary model is 3, implying that the degeneracy is very severe. For OGLE-2011-BLG-0950/MOA-2011-BLG-336, the stellar binary model is formally excluded with Δχ2 105 and the planetary model is preferred. However, it is difficult to claim a planet discovery because systematic residuals of data from the planetary model are larger than the difference between the planetary and binary models. Considering that two events observed during a single season suffer from such a degeneracy, it is expected that central perturbations experiencing this type of degeneracy is common.",
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TY - JOUR

T1 - A new type of ambiguity in the planet and binary interpretations of central perturbations of high-magnification gravitational microlensing events

AU - Choi, J. Y.

AU - Shin, I. G.

AU - Han, C.

AU - Udalski, A.

AU - Sumi, T.

AU - Gould, A.

AU - Bozza, V.

AU - Dominik, M.

AU - Fouqué, P.

AU - Horne, K.

AU - Szymański, M. K.

AU - Kubiak, M.

AU - Soszyński, I.

AU - Pietrzyński, G.

AU - Poleski, R.

AU - Ulaczyk, K.

AU - Pietrukowicz, P.

AU - Kozłowski, S.

AU - Skowron, J.

AU - Wyrzykowski,

AU - Abe, F.

AU - Bennett, D. P.

AU - Bond, I. A.

AU - Botzler, C. S.

AU - Chote, P.

AU - Freeman, M.

AU - Fukui, A.

AU - Furusawa, K.

AU - Itow, Y.

AU - Kobara, S.

AU - Ling, C. H.

AU - Masuda, K.

AU - Matsubara, Y.

AU - Miyake, N.

AU - Muraki, Y.

AU - Ohmori, K.

AU - Ohnishi, K.

AU - Rattenbury, N. J.

AU - Saito, To

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 - Bramich, D. M.

AU - Snodgrass, C.

AU - Steele, I. A.

AU - Street, R. A.

AU - Tsapras, Y.

AU - Al-Subai, Khalid

AU - Browne, P.

AU - Burgdorf, M. J.

AU - Calchi Novati, S.

AU - Dodds, P.

AU - Dreizler, S.

AU - Fang, X. S.

AU - Grundahl, F.

AU - Gu, C. H.

AU - Hardis, S.

AU - Harpsoe, K.

AU - Hinse, T. C.

AU - Hornstrup, A.

AU - Hundertmark, M.

AU - Jessen-Hansen, J.

AU - Jorgensen, U. G.

AU - Kains, N.

AU - Kerins, E.

AU - Liebig, C.

AU - Lund, M.

AU - Lunkkvist, M.

AU - Mancini, L.

AU - Mathiasen, M.

AU - Penny, M. T.

AU - Rahvar, S.

AU - Ricci, D.

AU - Scarpetta, G.

AU - Skottfelt, J.

AU - Southworth, J.

AU - Surdej, J.

AU - Tregloan-Reed, J.

AU - Wambsganss, J.

AU - Wertz, O.

AU - Almeida, L. A.

AU - Batista, V.

AU - Christie, G.

AU - Depoy, D. L.

AU - Dong, Subo

AU - Gaudi, B. S.

AU - Henderson, C.

AU - Jablonski, F.

AU - Lee, C. U.

AU - McCormick, J.

AU - McGregor, D.

AU - Moorhouse, D.

AU - Natusch, T.

AU - Ngan, H.

AU - Pogge, R. W.

AU - Tan, T. G.

AU - Thornley, G.

AU - Yee, J. C.

AU - Albrow, M. D.

AU - Bachelet, E.

AU - Beaulieu, J. P.

AU - Brillant, S.

AU - Cassan, A.

AU - Cole, A. A.

AU - Corrales, E.

AU - Coutures, C.

AU - Dieters, S.

AU - Dominis Prester, D.

AU - Donatowicz, J.

AU - Greenhill, J.

AU - Kubas, D.

AU - Marquette, J. B.

AU - Menzies, J. W.

AU - Sahu, K. C.

AU - Zub, M.

PY - 2012/8/24

Y1 - 2012/8/24

N2 - High-magnification microlensing events provide an important channel to detect planets. Perturbations near the peak of a high-magnification event can be produced either by a planet or a binary companion. It is known that central perturbations induced by both types of companions can be generally distinguished due to the essentially different magnification pattern around caustics. In this paper, we present a case of central perturbations for which it is difficult to distinguish the planetary and binary interpretations. The peak of a lensing light curve affected by this perturbation appears to be blunt and flat. For a planetary case, this perturbation occurs when the source trajectory passes the negative perturbation region behind the back end of an arrowhead-shaped central caustic. For a binary case, a similar perturbation occurs for a source trajectory passing through the negative perturbation region between two cusps of an astroid-shaped caustic. We demonstrate the degeneracy for two high-magnification events of OGLE-2011-BLG-0526 and OGLE-2011-BLG-0950/MOA-2011- BLG-336. For OGLE-2011-BLG-0526, the χ2 difference between the planetary and binary model is 3, implying that the degeneracy is very severe. For OGLE-2011-BLG-0950/MOA-2011-BLG-336, the stellar binary model is formally excluded with Δχ2 105 and the planetary model is preferred. However, it is difficult to claim a planet discovery because systematic residuals of data from the planetary model are larger than the difference between the planetary and binary models. Considering that two events observed during a single season suffer from such a degeneracy, it is expected that central perturbations experiencing this type of degeneracy is common.

AB - High-magnification microlensing events provide an important channel to detect planets. Perturbations near the peak of a high-magnification event can be produced either by a planet or a binary companion. It is known that central perturbations induced by both types of companions can be generally distinguished due to the essentially different magnification pattern around caustics. In this paper, we present a case of central perturbations for which it is difficult to distinguish the planetary and binary interpretations. The peak of a lensing light curve affected by this perturbation appears to be blunt and flat. For a planetary case, this perturbation occurs when the source trajectory passes the negative perturbation region behind the back end of an arrowhead-shaped central caustic. For a binary case, a similar perturbation occurs for a source trajectory passing through the negative perturbation region between two cusps of an astroid-shaped caustic. We demonstrate the degeneracy for two high-magnification events of OGLE-2011-BLG-0526 and OGLE-2011-BLG-0950/MOA-2011- BLG-336. For OGLE-2011-BLG-0526, the χ2 difference between the planetary and binary model is 3, implying that the degeneracy is very severe. For OGLE-2011-BLG-0950/MOA-2011-BLG-336, the stellar binary model is formally excluded with Δχ2 105 and the planetary model is preferred. However, it is difficult to claim a planet discovery because systematic residuals of data from the planetary model are larger than the difference between the planetary and binary models. Considering that two events observed during a single season suffer from such a degeneracy, it is expected that central perturbations experiencing this type of degeneracy is common.

KW - Galaxy: bulge

KW - gravitational lensing: micro

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U2 - 10.1088/0004-637X/756/1/48

DO - 10.1088/0004-637X/756/1/48

M3 - Article

VL - 756

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 48

ER -