Yes. I don't recall the upper limits, though.twistor said:So they could be out there (cosmic strings), but would have little contribution to structure formation. Is that right?
Cosmic strings are hypothetical one-dimensional objects proposed by string theory as a possible explanation for the formation of large-scale structures in the universe. Stringy inflation is a type of cosmic inflation driven by scalar fields in string theory. Currently, there is no direct evidence for the existence of cosmic strings or stringy inflation, but they are still actively studied and debated among scientists.
Cosmic strings are considered a potential outcome of stringy inflation, as they could have been formed during the rapid expansion of the universe in the early stages of the Big Bang. Stringy inflation also provides a theoretical framework for understanding the properties and behavior of cosmic strings.
One proposed method is to look for gravitational lensing effects caused by the presence of cosmic strings. Another method is to search for distortions in the cosmic microwave background radiation, which could be a result of cosmic strings interacting with the radiation. Additionally, some scientists are investigating the possibility of detecting gravitational waves produced by cosmic string collisions.
There have been some possible observational hints, such as the alignment of quasars and galaxies along the same direction, which could be caused by the gravitational effects of cosmic strings. However, these hints are still subject to debate and further investigation is needed to confirm the existence of cosmic strings.
The study of cosmic strings and stringy inflation is important because it provides a deeper understanding of the fundamental laws and forces that govern the universe. It also offers potential explanations for some of the biggest mysteries in cosmology, such as the origin of large-scale structures and the nature of dark matter and dark energy. Additionally, it allows for the development of new theories and models to be tested and refined through observations and experiments.