Direct observation of cosmic strings via their strong gravitational lensing effect – I. Predictions for high-resolution imaging surveys |
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Authors: | M Alice Gasparini Phil Marshall Tommaso Treu Eric Morganson Florian Dubath |
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Institution: | Physics Department, University of California, Santa Barbara, CA 93106, USA;KIPAC, PO Box 20450, MS29, Stanford, CA 94309, USA;KITP, University of California, Santa Barbara, CA 93106, USA |
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Abstract: | We use present theoretical estimates for the density of long cosmic strings to predict the number of strong gravitational lensing events in astronomical imaging surveys as a function of the angular resolution and survey area. We show that angular resolution is the single most important factor, and that interesting limits on the dimensionless string tension G μ/ c 2 can be obtained by existing and planned surveys. At the resolution of the Hubble Space Telescope ( HST ) (0.14 arcsec), it is sufficient to survey of the order of a few square degrees – well within reach of the current HST archive – to probe the regime G μ/ c 2∼ 10−7 . If lensing by cosmic strings is not detected, such a survey would improve the limit on the string tension by a factor of two over that available from the cosmic microwave background. Future high resolution imaging surveys, covering a few hundred square degrees or more, either from space in the optical or from large-format radio telescopes on the ground, would be able to further lower this limit to G μ/ c 2∼ 10−8 . These limits will not be improved significantly by increasing the solid angle of the survey. |
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Keywords: | gravitational lensing surveys cosmology: observations |
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