Search for cosmic strings in the COSMOS survey

Christiansen, J. L.; Albin, Eric; Fletcher, Thomas J.; Goldman, James A.; Teng, I. P.W.; Foley, Michael; Smoot, George F.

doi:10.1103/physrevd.83.122004

Cited by 27 publications

(25 citation statements)

References 41 publications

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“…Such events have special features which can distinguish them from "normal" lenses (that is, no magnification, identical images, odd number of images) and can be observed in searches for gravitational lenses. The most recent constraint set from such searches was in [115,116] where the authors used archival data from the HST (GOODS and COSMOS surveys respectively) to search for lensing events that could have been caused by straight cosmic strings, managing to set a bound slightly weaker than the CMB one Gµ/c 2 < 3.0 × 10 −7 , at 95% confidence level. We note, that these constraints are also sensitive to some of the modeling issues which are important in the CMB case.…”

Section: Discussionmentioning

confidence: 99%

Constraints on cosmic string tension imposed by the limit on the stochastic gravitational wave background from the European Pulsar Timing Array

2012

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We investigate the constraints that can be placed on the cosmic string tension by using the current Pulsar Timing Array (PTA) limits on the gravitational wave background. We have developed a code to compute the spectrum of gravitational waves (GWs) based on the widely accepted one-scale model. In its simplest form the one-scale model for cosmic strings allows one to vary: (i) the string tension, Gµ/c 2 ; (ii) the size of cosmic string loops relative to the horizon at birth, α; (iii) the spectral index of the emission spectrum, q; (iv) the cut-off in the emission spectrum, n * ; and (v) the intercommutation probability, p. The amplitude and slope of the spectrum in the nHz frequency range is very sensitive to these unknown parameters. We have also investigated the impact of more complicated scenarios with multiple initial loop sizes α, in particular the 2-α models proposed in the literature and a log-normal distribution for α. We have computed the constraint on Gµ/c 2 due to the limit on a stochastic background of GWs imposed by the European Pulsar Timing Array (EPTA). Taking into account all the possible uncertainties in the parameters we find a conservative upper limit of Gµ/c 2 < 5.3 × 10 −7 which typically occurs when the loop production scale is close to the gravitational backreaction scale, α ≈ ΓGµ/c 2 . Stronger limits are possible for specific values of the parameters which typically correspond to the extremal cases α ≪ ΓGµ/c 2 and α ≫ ΓGµ/c 2 . This limit is less stringent than the previously published limits which are based on cusp emission, an approach which does not necessarily model all the possible uncertainties. We discuss the prospects for lowering this limit by two orders of magnitude, or even a detection of the GW background, in the very near future in the context of the Large European Array for Pulsars (LEAP) and the Square Kilometre Array (SKA).

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Section: Discussionmentioning

confidence: 99%

Constraints on cosmic string tension imposed by the limit on the stochastic gravitational wave background from the European Pulsar Timing Array

2012

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“…Limits from optical lensing in fields of background galaxies rely on the theoretically well-understood deficit angle geometry of a string in spacetime but require a precise accounting for observational selection effects. Analysis of the GOODS and COSMOS optical surveys [90,91] yields Gµ < 3 × 10 −7 . Taken together these observations imply Gµ < ∼ 1-3 × 10 −7 .…”

Section: Current Bounds On String Tensionmentioning

confidence: 99%

Inflation, string theory and cosmic strings

Chernoff

Tye

2015

Int. J. Mod. Phys. D

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At its very beginning, the universe is believed to have grown exponentially in size via the mechanism of inflation. The almost scale-invariant density perturbation spectrum predicted by inflation is strongly supported by cosmological observations, in particular the cosmic microwave background radiation. However, the universe's precise inflationary scenario remains a profound problem for cosmology and for fundamental physics. String theory, the most-studied theory as the final physical theory of nature, should provide an answer to this question. Some of the proposals on how inflation is realized in string theory are reviewed. Since everything is made of strings, some string loops of cosmological sizes are likely to survive in the hot big bang that followed inflation. They appear as cosmic strings, which can have intricate properties. Because of the warped geometry in flux compactification of the extra spatial dimensions in string theory, some of the cosmic strings may have tensions substantially below the Planck or string scale. Such strings cluster in a manner similar to dark matter leading to hugely enhanced densities. As a result, numerous fossil remnants of the low tension cosmic strings may exist within the galaxy. They can be revealed through the optical lensing of background stars in the near future and studied in detail through gravitational wave emission. We anticipate that these cosmic strings will permit us to address central questions about the properties of string theory as well as the birth of our universe.

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“…e.g. [574]), but microlensing of stars within the galaxy [575] (rather than of distant quasars [576]) could probe very low tensions, particularly if the string loops cluster substantially [577]. 24 Cosmic strings of even lower tension might be detectable if they passed through the Earth [590], causing devastating earthquakes while simultaneously providing a window on Planck-scale physics.…”

Section: Cosmic Stringsmentioning

confidence: 99%