DIFFRACTION EFFECTS IN MICROLENSING OF Q2237+0305

Abstract

Geometrical optics provides an excellent description for quasar images crossing caustics which are formed by gravitational microlensing of objects like Q2237+0305. Within this approximation the source size can be estimated from the maximum magnification reached at caustic crossings. We evaluate the limitations imposed by diffraction on caustics using the formalism developed by Ulmer & Goodman (1995). Close to a caustic a new characteristic length, smaller that the Fresnel length, enters the problem, limiting the angular resolution to about 0.2 pico arcsecond, or equivalently about 3*10^9 cm at the source. To achieve this resolution the brightness must be monitored at time intervals of a few seconds. If a significant fraction of quasar luminosity comes from sources smaller than those limits then interference effects would make the observed intensity oscillate, in a close analogy with a two slit experiment. The characteristic period of such oscillations is expected to be about one tenth of a minute. If such oscillations are detected then photometry carried out at a single site may permit the determination of the caustic transverse velocity, and therefore may permit a direct conversion of the time units of brightness variations to the linear units at the source. Subject headings: Gravitational lensing - dark matter - quasars: structure -quasars: Q2237+0305

10 pages, plain TEX file, no figures. Submitted to ApJ postscript available at by anonymous ftp at ftp://astro.princeton.edu/library/preprint/pop615.ps.Z

Cited by in corpus (10)

• Formalism for testing theories of gravity using lensing by compact objects. III: Braneworld gravity
• The Optical Gravitational Lensing Experiment. A Hunt for Caustic Crossings in QSO 2237+0305
• Wave effects in the microlensing of pulsars and FRBs by point masses
• Probing Structures of Distant Extrasolar Planets with Microlensing
• Diffractive Microlensing I: Flickering Planetesimals at the Edge of the Solar System
• Studying wave optics in the light curve of exoplanet microlensing
• Gravitational Wave detection through microlensing?
• Extended Source Diffraction Effects Near Gravitational Lens Fold Caustics
• Primordial black hole detection through diffractive microlensing
• Probing Binary Lens Caustics with Gravitational Waves: A Uniform Approximation Approach