SIMBAD references

2004ApJ...606..319G - Astrophys. J., 606, 319-325 (2004/May-1)

Resolution of the MACHO-LMC-5 puzzle: the jerk-parallax microlens degeneracy.


Abstract (from CDS):

By extending the constant-acceleration analysis of Smith, Mao, & Paczy{nacute}ski to include jerk, I show that microlens parallax measurements are subject to a four-fold discrete degeneracy. The new degeneracy is characterized by a projected velocity v{d5}j=-(3/4)cscβec(cos\ul 2ψsin\ul 2βec+sin\ul 2ψ)3/2v, where βecis the ecliptic latitude, ψ is the phase of the Earth's orbit relative to opposition at the time of the event maximum, and v=30km/s is the speed of the Earth. The degeneracy becomes important when the lens projected velocity v{d5} is of order v{d5}j. For events toward the Large Magellanic Cloud, v{d5}j≃(3/4)v, so this degeneracy is important primarily for lenses in the Milky Way disk. In particular, it solves the puzzle of MACHO-LMC-5, whose microlens parallax measurement had yielded mass and distance determinations for the lens that were inconsistent with photometric estimates. Toward the Galactic bulge, v{d5}jranges from ∼0.2 km/s at the summer solstice to ∼200 km/s at the equinoxes, so the effect of the degeneracy depends strongly on the peak time of the event. The degeneracy applies mainly to events with Einstein timescales, tE≲yr/2π.

Abstract Copyright:

Journal keyword(s): Cosmology: Gravitational Lensing - Stars: Low-Mass, Brown Dwarfs

Simbad objects: 3

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