Physics

Why neutrinos?

Neutrinos are the most abundant particles in the Universe.
The Universe is transparent for neutrinos.
Since neutrinos are electrically neutral, they are hardly absorbed by any matter or deflected by magnetic fields.
A tremendous flow of neutrinos arrives at the Earth along straight lines pointing back to its source. Neutrinos carry undistorted information about phenomena, objects, and events in which they were produced, even if the events took place far away, in the most distant cosmic corners.

What can neutrinos tell us?

Neutrinos can promote our understanding of the early stage of the Universe’s evolution, dark matter and dark energy, formation of chemical elements, evolution of stars, inner structure and composition of the Sun and the Earth, and of neutrino properties.

Where are neutrino telescopes placed?

Large neutrino telescopes are placed in different locations on Earth, deep in transparent natural media:

in Lake Baikal (fresh water),
at the South Pole (ice),
in the Mediterranean Sea (salt water).

What is the method for neutrino detection?

The method for deep underwater neutrino detection was first proposed by M. A. Markov in 1960 — recording Cherenkov radiation from secondary muons and/or high-energy showers produced by neutrinos during their interactions with matter in transparent natural media.

What is Baikal-GVD aimed at?

The Baikal-GVD Neutrino Telescope is aimed at investigating the most violent processes in the Universe which accelerate charged particles to the highest energies, far beyond the reach of laboratory experiments on Earth. It is believed that these processes are accompanied by neutrino emission.

What makes Baikal-GVD efficient?

A large detection volume combined with a very good angular and energy resolution and the moderate light background in the fresh water of Lake Baikal allows efficiently studying the diffuse neutrino flux and also neutrinos from individual astrophysical objects, steady or transient.

A high angular resolution for track-like or cascade-like events (~0.25° for muon tracks and ~2° for cascades, respectively) provides a high capability of identifying point-like cosmic-ray accelerators.

Baikal-GVD’s alert system will provide a fast online neutrino event reconstruction and – if predefined conditions are satisfied – send an alert message to other communities worldwide.

Baikal-GVD will substantially contribute to multimessenger studies.

Why does a multimessenger approach count?

Multimessenger astronomy is a combination of observations with cosmic rays, neutrinos, photons of all wavelengths, and even gravitational waves. It represents a powerful tool in providing a multifaceted picture of physical processes driving the non-thermal Universe.

Multimessenger methods will relate Baikal-GVD’s findings to those of classical astronomy and X-ray or gamma-ray observations.

Combined analyses of cosmic high-energy neutrinos with spatially or temporarily coinciding gamma rays (or spatially coinciding ultrahigh-energy cosmic rays) may lead to a higher significance of results.

What are astrophysical neutrino sources?

The closest (from the perspective of a terrestrial observer) astrophysical objects that are currently assumed to be capable of emitting high-intensity neutrino fluxes are mainly located in the vicinity of the Galactic Center and in the Galactic Plane.

The most promising galactic candidates for neutrino emission are supernova remnants, pulsars, the neighborhood of the black hole Sgr A* at the Galactic Center, binary systems comprising a black hole or a neutron star, and clusters of molecular clouds.

Other neutrino sources are extragalactic objects. Some of them will be targeted by Baikal-GVD – Active Galactic Nuclei (AGN), Gamma-Ray Bursts (GRB), starburst galaxies, and galaxy clusters.