Binary microlensing events from the MACHO Project

C. Alcock, R. A. Allsman, D. Alves, T. S. Axelrod, D. Baines, A. C. Becker, D. P. Bennett, A. Bourke, A. Brakel, K. H. Cook, B. Crook, A. Crouch, J. Dan, A. J. Drake, P. C. Fragile, K. C. Freeman, A. Gal-Yam, M. Geha, J. Gray, K. GriestA. Gurtierrez, A. Heller, J. Howard, B. R. Johnson, S. Kaspi, M. Keane, O. Kovo, C. Leach, T. Leach, E. M. Leibowitz, M. J. Lehner, Y. Lipkin, D. Maoz, S. L. Marshall, M. Mcdowell, S. Mckeown, H. Mendelson, B. Messenger, D. Minniti, C. Nelson, B. A. Peterson, P. Popowski, E. Pozza, P. Purcell, M. R. Pratt, J. Quinn, P. J. Quinn, S. H. Rhie, A. W. Rodgers, A. Salmon, O. Shemmer, P. Stetson, C. W. Stubbs, W. Sutherland, S. Thomson, A. Tomaney, T. Vandehei, A. Walker, K. Ward, G. Wyper

Resultado de la investigación: Article

66 Citas (Scopus)

Resumen

We present the light curves of 21 gravitational microlensing events from the first six years of the MACHO Project gravitational microlensing survey that are likely examples of lensing by binary systems. These events were manually selected from a total sample of ∼350 candidate microlensing events that were either detected by the MACHO Alert System or discovered through retrospective analyses of the MACHO database. At least 14 of these 21 events exhibit strong (caustic) features, and four of the events are well fit with lensing by large mass ratio (brown dwarf or planetary) systems, although these fits are not necessarily unique. The total binary event rate is roughly consistent with predictions based upon our knowledge of the properties of binary stars, but a precise comparison cannot be made without a determination of our binary lens event detection efficiency. Toward the Galactic bulge, we find a ratio of caustic crossing to noncaustic crossing binary lensing events of 12:4, excluding one event for which we present two fits. This suggests significant incompleteness in our ability to detect and characterize non-caustic crossing binary lensing. The distribution of mass ratios, N(q), for these binary lenses appears relatively flat. We are also able to reliably measure source-face crossing times in four of the bulge caustic crossing events, and recover from them a distribution of lens proper motions, masses, and distances consistent with a population of Galactic bulge lenses at a distance of 7 ± 1 kpc. This analysis yields two systems with companions of ∼0.05 M.

Idioma originalEnglish
Páginas (desde-hasta)270-297
Número de páginas28
PublicaciónAstrophysical Journal
Volumen541
N.º1 PART 1
EstadoPublished - 20 sep 2000

Huella dactilar

massive compact halo objects
lenses
alkalies
galactic bulge
mass ratios
prediction
project
planetary systems
binary stars
proper motion
distribution
light curve

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Citar esto

Alcock, C., Allsman, R. A., Alves, D., Axelrod, T. S., Baines, D., Becker, A. C., ... Wyper, G. (2000). Binary microlensing events from the MACHO Project. Astrophysical Journal, 541(1 PART 1), 270-297.
Alcock, C. ; Allsman, R. A. ; Alves, D. ; Axelrod, T. S. ; Baines, D. ; Becker, A. C. ; Bennett, D. P. ; Bourke, A. ; Brakel, A. ; Cook, K. H. ; Crook, B. ; Crouch, A. ; Dan, J. ; Drake, A. J. ; Fragile, P. C. ; Freeman, K. C. ; Gal-Yam, A. ; Geha, M. ; Gray, J. ; Griest, K. ; Gurtierrez, A. ; Heller, A. ; Howard, J. ; Johnson, B. R. ; Kaspi, S. ; Keane, M. ; Kovo, O. ; Leach, C. ; Leach, T. ; Leibowitz, E. M. ; Lehner, M. J. ; Lipkin, Y. ; Maoz, D. ; Marshall, S. L. ; Mcdowell, M. ; Mckeown, S. ; Mendelson, H. ; Messenger, B. ; Minniti, D. ; Nelson, C. ; Peterson, B. A. ; Popowski, P. ; Pozza, E. ; Purcell, P. ; Pratt, M. R. ; Quinn, J. ; Quinn, P. J. ; Rhie, S. H. ; Rodgers, A. W. ; Salmon, A. ; Shemmer, O. ; Stetson, P. ; Stubbs, C. W. ; Sutherland, W. ; Thomson, S. ; Tomaney, A. ; Vandehei, T. ; Walker, A. ; Ward, K. ; Wyper, G. / Binary microlensing events from the MACHO Project. En: Astrophysical Journal. 2000 ; Vol. 541, N.º 1 PART 1. pp. 270-297.
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title = "Binary microlensing events from the MACHO Project",
abstract = "We present the light curves of 21 gravitational microlensing events from the first six years of the MACHO Project gravitational microlensing survey that are likely examples of lensing by binary systems. These events were manually selected from a total sample of ∼350 candidate microlensing events that were either detected by the MACHO Alert System or discovered through retrospective analyses of the MACHO database. At least 14 of these 21 events exhibit strong (caustic) features, and four of the events are well fit with lensing by large mass ratio (brown dwarf or planetary) systems, although these fits are not necessarily unique. The total binary event rate is roughly consistent with predictions based upon our knowledge of the properties of binary stars, but a precise comparison cannot be made without a determination of our binary lens event detection efficiency. Toward the Galactic bulge, we find a ratio of caustic crossing to noncaustic crossing binary lensing events of 12:4, excluding one event for which we present two fits. This suggests significant incompleteness in our ability to detect and characterize non-caustic crossing binary lensing. The distribution of mass ratios, N(q), for these binary lenses appears relatively flat. We are also able to reliably measure source-face crossing times in four of the bulge caustic crossing events, and recover from them a distribution of lens proper motions, masses, and distances consistent with a population of Galactic bulge lenses at a distance of 7 ± 1 kpc. This analysis yields two systems with companions of ∼0.05 M⊙.",
keywords = "Binaries: general, Dark matter, Gravitational lensing, Stars: low-mass, brown dwarfs",
author = "C. Alcock and Allsman, {R. A.} and D. Alves and Axelrod, {T. S.} and D. Baines and Becker, {A. C.} and Bennett, {D. P.} and A. Bourke and A. Brakel and Cook, {K. H.} and B. Crook and A. Crouch and J. Dan and Drake, {A. J.} and Fragile, {P. C.} and Freeman, {K. C.} and A. Gal-Yam and M. Geha and J. Gray and K. Griest and A. Gurtierrez and A. Heller and J. Howard and Johnson, {B. R.} and S. Kaspi and M. Keane and O. Kovo and C. Leach and T. Leach and Leibowitz, {E. M.} and Lehner, {M. J.} and Y. Lipkin and D. Maoz and Marshall, {S. L.} and M. Mcdowell and S. Mckeown and H. Mendelson and B. Messenger and D. Minniti and C. Nelson and Peterson, {B. A.} and P. Popowski and E. Pozza and P. Purcell and Pratt, {M. R.} and J. Quinn and Quinn, {P. J.} and Rhie, {S. H.} and Rodgers, {A. W.} and A. Salmon and O. Shemmer and P. Stetson and Stubbs, {C. W.} and W. Sutherland and S. Thomson and A. Tomaney and T. Vandehei and A. Walker and K. Ward and G. Wyper",
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Alcock, C, Allsman, RA, Alves, D, Axelrod, TS, Baines, D, Becker, AC, Bennett, DP, Bourke, A, Brakel, A, Cook, KH, Crook, B, Crouch, A, Dan, J, Drake, AJ, Fragile, PC, Freeman, KC, Gal-Yam, A, Geha, M, Gray, J, Griest, K, Gurtierrez, A, Heller, A, Howard, J, Johnson, BR, Kaspi, S, Keane, M, Kovo, O, Leach, C, Leach, T, Leibowitz, EM, Lehner, MJ, Lipkin, Y, Maoz, D, Marshall, SL, Mcdowell, M, Mckeown, S, Mendelson, H, Messenger, B, Minniti, D, Nelson, C, Peterson, BA, Popowski, P, Pozza, E, Purcell, P, Pratt, MR, Quinn, J, Quinn, PJ, Rhie, SH, Rodgers, AW, Salmon, A, Shemmer, O, Stetson, P, Stubbs, CW, Sutherland, W, Thomson, S, Tomaney, A, Vandehei, T, Walker, A, Ward, K & Wyper, G 2000, 'Binary microlensing events from the MACHO Project', Astrophysical Journal, vol. 541, n.º 1 PART 1, pp. 270-297.

Binary microlensing events from the MACHO Project. / Alcock, C.; Allsman, R. A.; Alves, D.; Axelrod, T. S.; Baines, D.; Becker, A. C.; Bennett, D. P.; Bourke, A.; Brakel, A.; Cook, K. H.; Crook, B.; Crouch, A.; Dan, J.; Drake, A. J.; Fragile, P. C.; Freeman, K. C.; Gal-Yam, A.; Geha, M.; Gray, J.; Griest, K.; Gurtierrez, A.; Heller, A.; Howard, J.; Johnson, B. R.; Kaspi, S.; Keane, M.; Kovo, O.; Leach, C.; Leach, T.; Leibowitz, E. M.; Lehner, M. J.; Lipkin, Y.; Maoz, D.; Marshall, S. L.; Mcdowell, M.; Mckeown, S.; Mendelson, H.; Messenger, B.; Minniti, D.; Nelson, C.; Peterson, B. A.; Popowski, P.; Pozza, E.; Purcell, P.; Pratt, M. R.; Quinn, J.; Quinn, P. J.; Rhie, S. H.; Rodgers, A. W.; Salmon, A.; Shemmer, O.; Stetson, P.; Stubbs, C. W.; Sutherland, W.; Thomson, S.; Tomaney, A.; Vandehei, T.; Walker, A.; Ward, K.; Wyper, G.

En: Astrophysical Journal, Vol. 541, N.º 1 PART 1, 20.09.2000, p. 270-297.

Resultado de la investigación: Article

TY - JOUR

T1 - Binary microlensing events from the MACHO Project

AU - Alcock, C.

AU - Allsman, R. A.

AU - Alves, D.

AU - Axelrod, T. S.

AU - Baines, D.

AU - Becker, A. C.

AU - Bennett, D. P.

AU - Bourke, A.

AU - Brakel, A.

AU - Cook, K. H.

AU - Crook, B.

AU - Crouch, A.

AU - Dan, J.

AU - Drake, A. J.

AU - Fragile, P. C.

AU - Freeman, K. C.

AU - Gal-Yam, A.

AU - Geha, M.

AU - Gray, J.

AU - Griest, K.

AU - Gurtierrez, A.

AU - Heller, A.

AU - Howard, J.

AU - Johnson, B. R.

AU - Kaspi, S.

AU - Keane, M.

AU - Kovo, O.

AU - Leach, C.

AU - Leach, T.

AU - Leibowitz, E. M.

AU - Lehner, M. J.

AU - Lipkin, Y.

AU - Maoz, D.

AU - Marshall, S. L.

AU - Mcdowell, M.

AU - Mckeown, S.

AU - Mendelson, H.

AU - Messenger, B.

AU - Minniti, D.

AU - Nelson, C.

AU - Peterson, B. A.

AU - Popowski, P.

AU - Pozza, E.

AU - Purcell, P.

AU - Pratt, M. R.

AU - Quinn, J.

AU - Quinn, P. J.

AU - Rhie, S. H.

AU - Rodgers, A. W.

AU - Salmon, A.

AU - Shemmer, O.

AU - Stetson, P.

AU - Stubbs, C. W.

AU - Sutherland, W.

AU - Thomson, S.

AU - Tomaney, A.

AU - Vandehei, T.

AU - Walker, A.

AU - Ward, K.

AU - Wyper, G.

PY - 2000/9/20

Y1 - 2000/9/20

N2 - We present the light curves of 21 gravitational microlensing events from the first six years of the MACHO Project gravitational microlensing survey that are likely examples of lensing by binary systems. These events were manually selected from a total sample of ∼350 candidate microlensing events that were either detected by the MACHO Alert System or discovered through retrospective analyses of the MACHO database. At least 14 of these 21 events exhibit strong (caustic) features, and four of the events are well fit with lensing by large mass ratio (brown dwarf or planetary) systems, although these fits are not necessarily unique. The total binary event rate is roughly consistent with predictions based upon our knowledge of the properties of binary stars, but a precise comparison cannot be made without a determination of our binary lens event detection efficiency. Toward the Galactic bulge, we find a ratio of caustic crossing to noncaustic crossing binary lensing events of 12:4, excluding one event for which we present two fits. This suggests significant incompleteness in our ability to detect and characterize non-caustic crossing binary lensing. The distribution of mass ratios, N(q), for these binary lenses appears relatively flat. We are also able to reliably measure source-face crossing times in four of the bulge caustic crossing events, and recover from them a distribution of lens proper motions, masses, and distances consistent with a population of Galactic bulge lenses at a distance of 7 ± 1 kpc. This analysis yields two systems with companions of ∼0.05 M⊙.

AB - We present the light curves of 21 gravitational microlensing events from the first six years of the MACHO Project gravitational microlensing survey that are likely examples of lensing by binary systems. These events were manually selected from a total sample of ∼350 candidate microlensing events that were either detected by the MACHO Alert System or discovered through retrospective analyses of the MACHO database. At least 14 of these 21 events exhibit strong (caustic) features, and four of the events are well fit with lensing by large mass ratio (brown dwarf or planetary) systems, although these fits are not necessarily unique. The total binary event rate is roughly consistent with predictions based upon our knowledge of the properties of binary stars, but a precise comparison cannot be made without a determination of our binary lens event detection efficiency. Toward the Galactic bulge, we find a ratio of caustic crossing to noncaustic crossing binary lensing events of 12:4, excluding one event for which we present two fits. This suggests significant incompleteness in our ability to detect and characterize non-caustic crossing binary lensing. The distribution of mass ratios, N(q), for these binary lenses appears relatively flat. We are also able to reliably measure source-face crossing times in four of the bulge caustic crossing events, and recover from them a distribution of lens proper motions, masses, and distances consistent with a population of Galactic bulge lenses at a distance of 7 ± 1 kpc. This analysis yields two systems with companions of ∼0.05 M⊙.

KW - Binaries: general

KW - Dark matter

KW - Gravitational lensing

KW - Stars: low-mass, brown dwarfs

UR - http://www.scopus.com/inward/record.url?scp=0034692202&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0034692202

VL - 541

SP - 270

EP - 297

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 PART 1

ER -

Alcock C, Allsman RA, Alves D, Axelrod TS, Baines D, Becker AC y otros. Binary microlensing events from the MACHO Project. Astrophysical Journal. 2000 sep 20;541(1 PART 1):270-297.