Microlensing by cosmic strings |
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| Authors: | Konrad Kuijken Xavier Siemens Tanmay Vachaspati |
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| Institution: | Leiden Observatory, Leiden University, PO Box 9513, 2300RA Leiden, the Netherlands;LIGO Laboratory, California Institute of Technology, Pasadena, California 91125, USA Theoretical Astrophysics, California Institute of Technology, Pasadena, California 91125, USA;CERCA, Department of Physics, Case Western Reserve University, Cleveland, OH 44106-7079, USA |
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| Abstract: | 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. |
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| Keywords: | gravitational lensing cosmology: miscellaneous |
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