Science with the Cherenkov Telescope Array (1709.07997v2)

Abstract: The Cherenkov Telescope Array, CTA, will be the major global observatory for very high energy gamma-ray astronomy over the next decade and beyond. The scientific potential of CTA is extremely broad: from understanding the role of relativistic cosmic particles to the search for dark matter. CTA is an explorer of the extreme universe, probing environments from the immediate neighbourhood of black holes to cosmic voids on the largest scales. Covering a huge range in photon energy from 20 GeV to 300 TeV, CTA will improve on all aspects of performance with respect to current instruments. The observatory will operate arrays on sites in both hemispheres to provide full sky coverage and will hence maximize the potential for the rarest phenomena such as very nearby supernovae, gamma-ray bursts or gravitational wave transients. With 99 telescopes on the southern site and 19 telescopes on the northern site, flexible operation will be possible, with sub-arrays available for specific tasks. CTA will have important synergies with many of the new generation of major astronomical and astroparticle observatories. Multi-wavelength and multi-messenger approaches combining CTA data with those from other instruments will lead to a deeper understanding of the broad-band non-thermal properties of target sources. The CTA Observatory will be operated as an open, proposal-driven observatory, with all data available on a public archive after a pre-defined proprietary period. Scientists from institutions worldwide have combined together to form the CTA Consortium. This Consortium has prepared a proposal for a Core Programme of highly motivated observations. The programme, encompassing approximately 40% of the available observing time over the first ten years of CTA operation, is made up of individual Key Science Projects (KSPs), which are presented in this document.

• The paper presents CTA's groundbreaking sensitivity improvements, achieving photon detection from 20 GeV to 300 TeV with up to 1 arc-minute resolution.
• The paper details an innovative infrastructure of 118 telescopes across both hemispheres, enabling full-sky coverage and rapid transient detection.
• The paper highlights a Core Programme dedicating 40% of early operations to key projects, targeting dark matter, cosmic-ray acceleration, and AGN monitoring.

An Overview of "Science with the Cherenkov Telescope Array"

The document "Science with the Cherenkov Telescope Array" provides a comprehensive analysis of the scientific objectives and operational logistics associated with the Cherenkov Telescope Array (CTA). Positioned to be a pivotal platform in the domain of very high energy (VHE) gamma-ray astronomy, the CTA promises substantial advancements in the observational astronomy landscape.

Technological Capabilities

The CTA is designed to extend the traditional capabilities of Imaging Atmospheric Cherenkov Telescopes (IACTs) by offering outstanding sensitivity across a photon energy range spanning from 20 GeV to 300 TeV. Notably, it will possess an angular resolution reaching 1 arc-minute at high energies. This level of detail facilitates unprecedented imaging clarity and sensitivity, which marks a significant upgrade over current-generation instruments. The accelerated survey capability, reportedly 100 times faster than any preceding TeV telescopes, is projected to contribute vastly to time-domain astrophysics, enhancing sensitivity by three orders of magnitude on hour timescales compared to Fermi-LAT at 30 GeV.

Infrastructure and Operational Strategy

Comprising 99 telescopes in the southern hemisphere and 19 in the northern hemisphere, the CTA's geographic distribution enables full-sky coverage, which is critical in capturing transient and rare cosmic events such as local supernovae, GRBs, and GW transients. The flexibility of operative sub-arrays augments its scientific utility, accommodating a diverse range of observational campaigns.

Key Science Projects

The paper delineates the CTA’s Core Programme, which devotes approximately 40% of the observatory's first decade of operational time to a series of Key Science Projects (KSPs). These projects target phenomena including but not limited to:

• Dark Matter Studies: Investigating WIMPs through their annihilation signatures, with a focus on particle masses in the 200 GeV to 20 TeV range.
• Cosmic Ray PeVinstates: Systematic exploration of particle acceleration mechanisms across a spectrum of astrophysical environments, emphasizing the detection of PeV-scale acceleration within our galaxy.
• Surveys: Comprehensive surveys, including extragalactic, Galactic plane, and Large Magellanic Cloud surveys, to delineate the population and emission characteristics of diverse gamma-ray sources.
• Transients and Variable Sources: Rapid, localized observations pertinent to explosive astrophysical phenomena such as gamma-ray bursts.
• AGN Monitoring: Continuous investigation of active galactic nuclei to understand the physics of supermassive black holes and jet phenomena.

Multimessenger and Multiwavelength Synergy

The paper underscores the strategic integration of CTA data with other astronomical observatories in a multiwavelength and multimessenger framework. This collaboration aims to provide a holistic understanding of the non-thermal emission processes and source characteristics.

Data Accessibility

CTA operations are geared towards inclusivity and collaboration, maintaining a commitment to open data access post a designated proprietary period—typically one year. This approach ensures that the CTA's legacy data products continue to yield scientific yields that transcend their initial exploratory scope.

Conclusion

The Cherenkov Telescope Array strategy elucidated in the paper presents a robust foundation for future astrophysical research. Its broad-spectrum capabilities in VHE gamma-ray observation, combined with inclusive scientific programs, set the stage for potential breakthroughs in understanding the extreme universe. The complementary nature of CTA with other observation modalities is especially significant for integrated astrophysical studies, promising transformative insights into dark matter, cosmic ray origins, and transient cosmic events.