Discovery of cosmic strings: evidence for the existence of defects in the universe

A team of astrophysicists has announced that they have found evidence for the existence of cosmic strings, which are hypothesized defects in the universe resulting from its initial expansion. Cosmic strings were first proposed in the 1970s by theoretical physicist Tom W. B. Kibble and later taken up in string theory. These one-dimensional strings, much thinner than a proton, are thought to have formed in the first second of the universe and could span its entire length.

So far, cosmic strings have not been detected, although there have been some ideas about how to find them. However, when strings cross, they may provide an opportunity to find them. Once formed, a loop is expected to disappear over time, oscillating, radiating gravity, shrinking, and eventually evaporating. The pinch points of the loop, called cusps, are expected to produce powerful bursts of gravitational waves. In addition, cosmic strings are believed to be detectable in the cosmic microwave background (CMB), the remnant radiation from the Big Bang that pervades the entire known universe.

A team of astrophysicists recently found several potential candidates for cosmic strings, focusing on a region called CSc-1. If cosmic strings exist, they would be extremely dense and potentially detectable as a source of gravitational waves. They could also cause gravitational lensing, in which immensely heavy objects distort space-time, making distant objects appear larger to astronomers.

The team observed two galaxies in the region identified as the best candidate and found evidence of gravitational lensing. The two galaxies, which appear close together, may actually be one galaxy. Analyzing the data, the researchers found similar spectra between the two (or one) galaxies. Modeling the observational data showed that a large number of pairs can be explained by the complex geometry of the string. In particular, modeling of one pair of galaxies showed that the observed angle between the components of the pair can be explained if the string is strongly tilted with respect to the line of sight and curved in the image plane.

The team is cautious, as cosmic strings have not yet been detected, and plans to observe further potential evidence with more powerful telescopes. The study has been published on the arXiv preprint server and accepted for publication in the Bulletin de la Société Royale des Sciences de Liège.