# Physics Beyond the Standard Model With Pulsar Timing Arrays

## TL;DR

Pulsar timing arrays are poised to detect nanohertz gravitational waves, offering insights into supermassive black holes, exotic physics, early universe phenomena, modified gravity theories, and dark matter models within the next decade.

## Contribution

This paper discusses the potential of PTAs to explore new physics beyond the Standard Model, including gravitational waves from cosmic strings, inflation, phase transitions, and dark matter.

## Key findings

- PTAs can detect GWs from supermassive black hole binaries within 3-7 years.
- PTAs provide a unique probe for cosmic strings, inflation, and early universe phase transitions.
- PTAs enable tests of alternative gravitational theories and dark matter models.

## Abstract

Pulsar timing arrays (PTAs) will enable the detection of nanohertz gravitational waves (GWs) from a population of supermassive binary black holes (SMBBHs) in the next $\sim 3-7$ years. In addition, PTAs provide a rare opportunity to probe exotic physics. Potential sources of GWs in the nanohertz band include, cosmic strings and cosmic superstrings, inflation and, phase transitions in the early universe. GW observations will also make possible tests of gravitational theories that, by modifying Einstein's theory of general relativity, attempt to explain the origin of cosmic acceleration and reconcile quantum mechanics and gravity, two of the most profound challenges facing fundamental physics today. Finally, PTAs also provide a new means to probe certain dark matter models.