Letters of Intent received in 2022

LoI 2024-2186
The High-Energy Gamma-ray Universe: Current observations and future perspectives with wide-field gamma-ray facilities

Date: 8 August 2024 to 9 August 2024
Category: Focus meetings (GA)
Location: Cape Town, South Africa
Contact: Ulisses Barres de Almeida (ulisses@cbpf.br)
Coordinating division: Division D High Energy Phenomena and Fundamental Physics
Other divisions: Division B Facilities, Technologies and Data Science
Co-Chairs of SOC: Ulisses Barres de Almeida (Centro Brasileiro de Pesquisas Físicas)
Felix Aharonian (Dublin Institute for Advanced Studies)
Elisa Prandini (Università Degli Studi di Padova)
Gustavo Romero (Instituto Argentino de Radioastronomía)
Marcos Santander (University of Alabama)
Chair of LOC: Markus Böttcher (North-West University)



Cosmic Rays
Ground-based Gamma-ray Astronomy
High Energy Astrophysics
Multi-messenger Astrophysics
Wide-Field Gamma-ray Observatories
High Altitude Water Cherenkov Experiment (HAWC)
Large High Altitude Air Shower Observatory (LHAASO)
Southern Wide-Field Gamma-ray Observatory (SWGO)



Ground-based gamma-ray astronomy is now an established field, accumulating a plethora of breakthrough results over the past decade thanks to the current generation of imaging atmospheric Cherenkov telescopes (IACTs). The lack of new gamma-ray space missions in the medium-term future brings the success achieved by these facilities into greater focus, and further increases the expectations towards the start of operations of the next-generation Cherenkov Telescope Array (CTA).

In more recent years, nevertheless, we have witnessed the coming of age of a second group of instruments for the observation of the ultra-high energy sky from the ground: the wide-field particle sampling arrays, chiefly represented by the Large High Altitude Air Shower Observatory (LHAASO) and the High Altitude Water Cherenkov Observatory (HAWC). Since these facilities are both located in the Northern Hemisphere, plans are now ongoing for the installation of the first instrument of the kind below the Equator, the Southern Wide-Field Gamma-ray Observatory (SWGO).

These wide-field ground-based gamma-ray observatories are transit facilities highly complementary to the more traditional IACTs. They represent a valuable new probe of the highest energy universe, expanding the observational reach of Astronomy up to the petalectronvolt scale, where they can study extreme cosmic ray accelerators and a number of topics of fundamental physics.

In addition to the PeV window, new instrumental developments are pushing the working range of these wide-field facilities well below the TeV threshold, thus bridging the gap with all-sky monitoring satellites such as Fermi-LAT, whose limited collecting area restrict detection efficacy to energies below 100 GeV. In so doing, wide-field instruments not only become powerful probes of multi-messenger and extreme transient events, but also primary triggers for the coordinated follow-up of variable phenomena.

The purpose of this Focus Meeting will be to present and review the current status of wide-field gamma-ray observatories and discuss the many astrophysical problems that can be probed from their unique vantage point. With LHAASO being only on its first years of operation, and SWGO still in development phase, it is the right time to promote the discussion of this emerging field, still little represented in the existing IAU Commissions.

The following scientists already agreed to serve in the meeting SOC: Felix Aharonian (co-chair, Ireland), Denis Bastieri (Italy / China), Alessandro de Angelis (Italy), Michele Doro (Italy), Jim Hinton (Germany), Petra Huentemeyer (USA), Elisa Prandini (co-chair, Italy), Andreas Reisenegger (Chile), Gustavo Romero (co-chair, Argentina) and Adrián Rovero (Argentina).

The LOC will be chaired by Markus Böttcher, (South Africa).
The event is proposed to take place at the next IAU General Assembly in Cape Town.