Multi-messenger study of the high energy universe
The direct detection of gravitational waves, achieved in 2015 for the first time and announced in early 2016, will open a new observational window on the Universe that will complement the investigations based on optical telescopes, cosmic rays and neutrino detection.
- Laser Interferometer Gravitational-Wave Observatory (LIGO, USA)
- VIRGO (Italy)
- Gravitational Wave Detector GEO6000 (GEO-HF, Germany)
Upgrades of first generation interferometers are underway, commissioning of second generation instruments starting in 2015:
- Advanced LIGO (USA)
- Advanced Virgo (Italy)
- KAGRA (Japan)
- Einstein Telescope (Europe)
High Energy Photons
Gamma ray studies from ground, in the energy band from typically 100 GeV up to 30 TeV, became mature in the last decade. Operation of imaging atmospheric Cherenkov telescope arrays H.E.S.S. at the Southern hemisphere, and MAGIC and VERITAS at the Northern hemisphere, enabled the discovery of more than 150 different astrophysical source from more than 10 source populations.
- High Energy Stereoscopic System (H.E.S.S., Namibia)
- MAGIC (La Palma, Spain)
- Very Energetic Radiation Imaging Telescope Array System (VERITAS, USA)
- Cherenkov Telescope Array (CTA, Germany)
With its large, medium and small size telescope sub-arrays it will operate as an open access observatory. This is a high-rank project which from 2020 to well beyond 2030 will serve as a powerful multifunctional tool for study of the non-thermal Universe through high energy gamma rays. With an order of magnitude improved sensitivity with respect to its predecessors and a broader spectral coverage (down to 20 GeV and up to 300 TeV), CTA is expected to increase dramatically the number of very high energy sources, and to provide deeper insight into several topical research areas such as the origin of cosmic rays, physics and astrophysics of relativistic outflows, the level of the Extragalactic Background Radiation, etc. Major astroparticle objectives of CTA are the detection of dark matter, search for evidence of violation of the Lorentz Invariance, probes of extreme environments characterized by huge gravitational and magnetic fields, relativistic shocks, highly turbulent plasma.
CTA is complementary to the wide field surveys LHAASO (china) and HAWC (Mexico, US).
High Energy Neutrinos
Four collaborations, the ANTARES, Baikal, IceCube and KM3NeT, have formed a “Global Neutrino Network”, GNN, with the aim of developing a coherent strategy and to exploit the synergistic effects of cooperation.
- IceCube South Pole Neutrino Observatory (Antarctica)
The cubic-kilometre detector in the deep ice below the South Pole was completed in 2010, mainly funded by the US NSF and significant contributions of several European nations. The 2013 detection of a flux of high-energy (PeV-scale) cosmic neutrinos represents a major breakthrough in the field.
- Astronomy with a Neutrino Telescope and Abyss environmental RESearch (ANTARES, France)
The detector is placed in the Mediterranean Sea and represents a proof of concept for a deep-sea neutrino telescope.
- KM3NeT (Europe)
The next generation deep-sea neutrino telescope is currently successfully deploying and operating prototypes in two sites, Toulon (France) and Capo Passero (Italy). It is preparing for a new construction phase at the two sites and possibly a third site at Pylos (Greece). The first KM3NeT construction phase is fully funded and will be completed in 2015. As a next step, an intermediate stage is prepared, Km3NeT Phase-1.5, dedicated to investigate the neutrino flux detected by IceCube with a complementary field of view and different systematics.
- Gigaton Volume Detector in Lake Baikal (BAIKAL-GVD)
A cubic-kilometer scale detector in Lake Baikal (Russia)
- ORCA: May be deployed at the French KM3NeT site between 2016-2019
- PINGU: An infill array of IceCube, could start deployment around 2019
Both ORCA and PINGU offer the possibility of an early determination of the neutrino mass hierarchy, by measuring the matter effects on atmospheric neutrinos propagating through the Earth. They will also yield a high precision measurement of the atmospheric parameters of the neutrino mixing matrix. Both facilities will cover the relevant 3-15 GeV energy range by deploying a denser instrumentation of optical sensors.
High Energy Cosmic Rays
- Pierre Auger Observatory (Argentina)
The largest and most sensitive surface array in the world, it has a substantial European involvement. The main achievements so far include (i) precise measurements of the energy spectrum from 3 1017 eV to 1020 eV with a clear evidence of two spectral features, (ii) evidence of increasingly heavier mass composition above the ‘ankle’; (iii) meaningful upper limits on the fluxes of EeV neutrinos and gamma rays; (iv) relevant contributions to particle physics, for instance by determining the proton–‐proton cross section at very high energy. For the period 2015-2018, the Auger collaboration plans include continued operation and a detector upgrade.
- Telescope Array (USA)
A smaller air-shower detector at the Northern hemisphere, sensitive to the same energy range. It is located in the US, with large US and Japanese contributions and small European participation. Plans include increasing the array by a factor four to reach sufficient statistics for studying large-scale anisotropies of cosmic rays at highest energies.
Auger and Telescope Array work in specific aspects already together on a combined data analysis.