Microlensing Constraints on the Frequency of Jupiter-Mass Companions: Analysis of 5 Years of PLANET Photometry

B S Gaudi, M D Albrow, J An, J-P Beaulieu, J A R Caldwell, D L DePoy, Martin Dominik, A Gould, J Greenhill, K Hill, S Kane, R Martin, J Menzies, R M Naber, J-W Pel, R W Pogge, K R Pollard, P D Sackett, K C Sahu, P VermaakP M Vreeswijk, R Watson, A Williams, PLANET Collaboration

Research output: Contribution to journalArticlepeer-review

104 Citations (Scopus)

Abstract

We analyze 5 years of PLANET photometry of microlensing events toward the Galactic bulge to search for the short-duration deviations from single-lens light curves that are indicative of the presence of planetary companions to the primary microlenses. Using strict event-selection criteria, we construct a well-defined sample of 43 intensively monitored events. We search for planetary perturbations in these events over a densely sampled region of parameter space spanning two decades in mass ratio and projected separation, but find no viable planetary candidates. By combining the detection efficiencies of the events, we find that, at 95% confidence, less than 25% of our primary lenses have companions with mass ratio q=10(-2) and separations in the lensing zone, [0.6-1.6]theta(E), where theta(E) is the Einstein ring radius. Using a model of the mass, velocity, and spatial distribution of bulge lenses, we infer that the majority of our lenses are likely M dwarfs in the Galactic bulge. We conclude that less than 33% of M dwarfs in the Galactic bulge have companions with mass m(p)=M-J between 1.5 and 4 AU, and less than 45% have companions with m(p)=3M(J) between 1 and 7 AU, the first significant limits on planetary companions to M dwarfs. We consider the effects of the finite size of the source stars and changing our detection criterion, but find that these do not alter our conclusions substantially.

Original languageEnglish
Pages (from-to)463-499
Number of pages37
JournalAstrophysical Journal
Volume566
Issue number1
DOIs
Publication statusPublished - 10 Feb 2002

Keywords

  • gravitational lensing
  • planetary systems
  • stars : low-mass, brown dwarfs
  • GRAVITATIONAL LENSING EXPERIMENT
  • EVENT MACHO 98-SMC-1
  • GALACTIC-BULGE
  • EXTRASOLAR PLANETS
  • LIGHT CURVES
  • BINARY LENS
  • MULTIPLE LENSES
  • STARS
  • SYSTEMS
  • SEARCH

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