Microlensing by cosmic strings

Konrad Kuijken, Xavier Siemens, Tanmay Vachaspati

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


We consider the signature and detectability of gravitational microlensing of distant quasars by cosmic strings. Because of the simple image configuration such events will have a characteristic lightcurve, in which a source would appear to brighten by exactly a factor of 2, before reverting to its original apparent brightness. We calculate the optical depth and event rate, and conclude that current predictions and limits on the total length of strings on the sky imply optical depths of ≲ 10-8 and event rates of fewer than one event per 109 sources per year. Disregarding those predictions but replacing them with limits on the density of cosmic strings from the cosmic microwave background fluctuation spectrum, leaves only a small region of parameter space (in which the sky contains about 3 × 105 strings with deficit angle of the order of 0.3 milli-seconds) for which a microlensing survey of exposure 107 source years, spanning a 20-40-year period, might reveal the presence of cosmic strings.

Original languageEnglish (US)
Pages (from-to)161-164
Number of pages4
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Feb 2008
Externally publishedYes


  • Cosmology: miscellaneous
  • Gravitational lensing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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