# The Transient program of the Cherenkov Telescope Array

## TL;DR

The CTA Transient program aims to utilize the Cherenkov Telescope Array's advanced capabilities to explore short-timescale high-energy phenomena, including gamma-ray bursts and multi-messenger astrophysics, enabling new discoveries in the violent universe.

## Contribution

This paper introduces the CTA Transients program, detailing its science goals and its role in multi-messenger astrophysics, highlighting its novel focus on high-energy transient phenomena.

## Key findings

- Enhanced sensitivity to gamma-ray transients up to 300 TeV
- First high-statistics measurements of GRBs above 10 GeV
- Integration with multi-messenger alerts for comprehensive observations

## Abstract

The Cherenkov Telescope Array (CTA) is the next generation high-energy gamma-ray observatory. It will improve the sensitivity of current instruments up to an order of magnitude, while providing energy coverage for photons from 20 GeV to at least 300 TeV to reach high redshifts and extreme accelerators and will give access to the shortest time-scale phenomena. CTA is thus a uniquely powerful instrument for the exploration of the violent and variable universe. The ability to probe short timescales at the highest energies will allow CTA to explore the connection between accretion and ejection phenomena surrounding compact objects, investigate the processes occurring in relativistic outflows, and open up significant phase space for serendipitous discoveries. Aiming at playing a central role in the era of multi-messenger astrophysics, the CTA Transient program includes follow-up observations of a broad range of multi-wavelength and multi-messenger alerts, ranging from Galactic compact object binary systems to novel phenomena like Fast Radio Bursts. A promising case is that of gamma-ray bursts (GRBs), where CTA will for the first time enable high-statistics measurements above $\sim$ 10 GeV, probing new spectral components and shedding light on the physical processes at work in these systems. Dedicated programs searching for very-high-energy (VHE) gamma-ray counterparts to gravitational waves and high-energy neutrinos complete the CTA transients program. This contribution will introduce and outline the CTA Transients program. We will provide an overview of the various science topics and discuss the links to multi-messenger and multi-wavelength observations.