Introduction to Cosmic F- and D-Strings

TL;DR

This paper explores the theoretical possibility and observational prospects of superstrings of cosmic length, including gauge theory solitons and superstrings from string theory, emphasizing their potential detectability via gravitational waves.

Contribution

It provides a comprehensive, pedagogical overview of cosmic superstrings, their formation conditions, network properties, and observational signatures, especially in the context of string theory models of inflation.

Findings

Cosmic superstrings could be observable through gravitational wave signals.

Different types of superstrings may have distinguishable network properties.

Some string theory inflation models naturally produce observable cosmic superstrings.

Abstract

In these lectures I discuss the possibility that superstrings of cosmic length might exist and be observable. I first review the original idea of cosmic strings arising as gauge theory solitons, and discuss in particular their network properties and the observational bounds that rule out cosmic strings as the principal origin of structure in our universe. I then consider cosmic superstrings, including the `fundamental' F-strings and also D-strings and strings arising from wrapped branes. I discuss the conditions under which these will exist and be observable, and ways in which different kinds of string might be distinguished. We will see that each of these issues is model-dependent, but that some of the simplest models of inflation in string theory do lead to cosmic superstrings. Moreover, these could be the first objects seen in gravitational wave astronomy, and might have distinctive network properties. The outline of these lectures follows hep-th/0410082, but the treatment is more detailed and pedagogical.