Microlensing by Cosmic Strings

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 light curve, in which a source would appear to brighten by exactly a factor of two, 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 $\la 10^{-8}$ and event rates of fewer than one event per $10^9$ sources per year. Disregarding those predictions but replacing them with limits on the density of cosmic strings from the CMB fluctuation spectrum, leaves only a small region of parameter space (in which the sky contains about $3\times 10^5$ strings with deficit angle of order 0.3 milli-arcseconds) for which a microlensing survey of exposure $10^7$ source-years, spanning a 20--40-year period, might reveal the presence of cosmic strings.

4 pages, accepted for publication in MNRAS

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• Cosmic strings
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• Seeking String Theory in the Cosmos
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• First LIGO search for gravitational wave bursts from cosmic (super)strings
• The signature of primordial black holes in the dark matter halos of galaxies
• Cosmic Strings as the Source of Small-Scale Microwave Background Anisotropy
• Cosmic Superstrings
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• Observational constraints on light cosmic strings from photometry and pulsar timing
• String Vertex Operators and Cosmic Strings
• The effect of extra dimensions on gravity wave bursts from cosmic string cusps
• Magnetogenesis from Cosmic String Loops
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• Probing Cosmic Strings with Satellite CMB measurements
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• Clustering of Superstring Loops
• Perturbations of Spacetime around a Stationary Rotating Cosmic String
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• Covariant Vertex Operators for Cosmic Strings
• Femto-lensing due to a Cosmic String
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• Formation & evolution of cosmic superstrings: a short review
• Prospects of Cosmic Superstring Detection through Microlensing of Extragalactic Point-Like Sources
• Constraints on Flows in Horava-Lifshitz Gravity by Classical Solutions
• Radio Jets and Galaxies as Cosmic String Probes
• Weak lensing from self-ordering scalar fields
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