Femtolensing: Beyond the semiclassical approximation

Andrew Ulmer, Jeremy Goodman

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


Femtolensing is a gravitational lensing effect in which the magnification is a function not only of the positions and sizes of the source and lens, but also of the wavelength of light. Femtolensing is the only known effect of(10-13-10-16 M) dark-matter objects and may possibly be detectable in cosmological gamma-ray burst spectra. We present a new and efficient algorithm for femtolensing calculations in general potentials. The physical optics results presented here differ at low frequencies from the semiclassical approximation, in which the flux is attributed to a finite number of mutually coherent images. At higher frequencies, our results agree well with the semiclassical predictions. Applying our method to a point-mass lens with external shear, we find complex events that have structure at both large and small spectral resolution. In this way, we show that femtolensing may be observable for lenses up to 10-11 M, much larger than previously believed. Additionally, we discuss the possibility of a search for femtolensing of white dwarfs in the Large Magellanic Cloud at optical wavelengths.

Original languageEnglish (US)
Pages (from-to)67-75
Number of pages9
JournalAstrophysical Journal
Issue number1
StatePublished - Mar 20 1995

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Dark matter
  • Gamma rays: bursts
  • Gravitational lensing
  • Methods: numerical


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