Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) will be a next-generation ground-based observatory for very high energy gamma-ray astronomy. It will consist of two arrays of dishes, a southern-hemisphere array at ESO’s Paranal Observatory and a northern array on the island of La Palma, Spain. Gamma-rays are emitted by some of the hottest and most powerful objects in the Universe, such as supermassive black holes and supernovae.

CTA, with its large collecting area and wide sky coverage, will be the largest and most sensitive high-energy gamma-ray observatory in the world. The two arrays will detect gamma-rays with unprecedented accuracy and together will be 10 times more sensitive than existing instruments.

Three types of telescope are required to cover the full CTA energy range (20 gigaelectronvolts [GeV] to 300 teraelectronvolts [TeV]). Over its core energy range (100 GeV to 10 TeV), CTA will employ 40 Medium-Sized Telescopes distributed over the two array sites, accompanied by 8 Large-Sized Telescopes and 70 Small-Sized Telescopes (reaching below 100 GeV and above 10 TeV, respectively).

The current plan is that on completion, CTA will comprise 118 telescopes worldwide, with 19 dishes in the northern hemisphere and 99 dishes in the southern hemisphere. The northern hemisphere site is located at the Instituto de Astrofísica de Canarias Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands. The southern site is located at ESO’s Paranal Observatory, around ten kilometres southeast of the Very Large Telescope. This is one of the driest and most isolated regions on Earth — an astronomical paradise. Integrating CTA into the existing Paranal–Armazones infrastructure will allow it to take advantage of ESO’s state-of-the-art facilities.

Over 1400 scientists and engineers from five continents, 31 countries and over 200 research institutes are participating in the CTA project. The majority of ESO’s Member States are represented in the CTA Consortium.

Science with CTA

The Cherenkov Telescope Array will serve as an open facility to a wide astrophysics community. Its scientific potential is extremely broad, from understanding the role of relativistic cosmic particles to the search for dark matter. Observations made with CTA will aim to understand the influence of high-energy particles in the evolution of cosmic systems, and to study some of the most extreme and violent events that occur in the high-energy Universe. CTA will probe environments from the immediate neighbourhood of black holes to the cosmic voids on the largest scales. It may even lead to brand new physics as it studies the nature of matter and forces beyond the standard model.

Although the Earth’s atmosphere prevents gamma-rays from reaching the surface, their interactions with the atmosphere create ultra-high energy particles. These particles travel faster than the speed of light in air and as a result they emit a flash of eerie blue Cherenkov radiation — similar to a sonic boom created by an aircraft exceeding the speed of sound. CTA’s mirrors and high-speed cameras will capture these short-lived flashes and pinpoint their direction. This will allow each gamma-ray to be traced back to its cosmic source, allowing astronomers to address some of the most enduring mysteries in astrophysics.

CTA will have the capability to detect gamma-rays in the energy range from a few tens of GeV up to hundreds of TeV. At the lower energies, CTA will probe transient and time-variable gamma-ray events in the distant Universe; at the higher energies it will push observational astronomy into a previously unexplored part of the electromagnetic spectrum to give a completely new view of the sky.

CTA will see the sky in higher energy resolution than ever before, allowing it to search for annihilating dark matter particles, and it will also be able to slew rapidly to catch gamma-ray bursts as they explode.

More about CTA

• Read more on the Cherenkov Telescope Array website
• Paranal Observatory First Choice to Host World’s Largest Array of Gamma-ray Telescopes