The experimental setup of the ANTARES neutrino telescope: a dozen of detection lines of 450 m in length and separated by approximately 70 m from one another, with 75 photomultipliers each. Credit: F.Montanet, CNRS/IN2P3 and UJF for Antares. Produced with POV-ray.

 

The search for WIMP annihilation in the Sun

BY ELISA CHISARI . MARCH 2, 2013
FILED UNDER ANNIHILATION SIGNATURES, DARK MATTER, INSTRUMENTATION, NEUTRINOS, PARTICLE PHYSICS, WIMPS
Title: First Search for Dark Matter Annihilation in the Sun Using the ANTARES Neutrino Telescope
Authors: ANTARES Collaboration: S. Adrián-Martinez, I. Al Samarai, A. Albert, et al.
First Author Institution: Institut d’Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC) – Universitat Politècnica de València.

The quest for identifying the dark matter particle is well underway. Many experiments are relying on different detection methods to look for this elusive particle. In this paper, we discuss the work of the ANTARES (Astronomy with a Neutrino Telescope and Abyss environmental RESearch project) collaboration, which is using a neutrino telescope to search for signals of dark matter annihilation in the Sun.

Elusive WIMPs

Most of the matter in the Universe is not visible, it does not interact light. Think about it: casting light on something and seeing what we get back is the main physical mechanism we have of knowing it is there. In astronomy, we observe the light emitted by the object or the inverse, we notice light being absorbed by an object. However, most of the matter in the Universe will not allow us to perform that experiment. We know of its existence because of its gravitational influence on the evolution of the Universe, the dynamics of galaxies or its lensing signatures. The leading theory for “dark” matter is that it is made of WIMPs, weakly interacting massive particles that naturally arise in supersymmetry (SUSY), which is an extension of the Standard Model of particle physics.

In spite of all the gravitational evidence in favor of dark matter, we still have not had a definitive detection of dark matter particles. The literature on these searches is vast, with experiments looking for dark matter directly, through the recoil of targets that collide with dark matter particles or indirectly, through products of the annihilation or decay of dark matter particles. We gave a short overview of the recent advances of this field in this astrobite. We also described an interesting experimental design of a new type of dark matter detector here.

The WIMP annihilation signal

If dark matter is indeed a supersymmetric particle, when two dark matter particles collide, they annihilate into other particles (including photons, neutrinos and antimatter). Indirect dark matter experiments search for those products by looking at regions where we expect the dark matter density to be high. WIMPs can become gravitationally trapped in the center of the Sun, annihilate and produce neutrinos that can escape and reach the Earth. Neutrino telescopes, such as ANTARES, can be used to search for this signal.

How does ANTARES work?

Neutrino telescopes do not resemble optical telescopes at all. When neutrinos interact with the Earth or the atmosphere, they produce charged particles (muons). If the particles have very high energies (10 GeV-100TeV), they emit Cherenkov light as they traverse water.

The ANTARES telescope is located at ~2500 m underwater in the Mediterranean Sea. Its array of photomultipliers collects the Cherenkov light with the aim of reconstructing the direction of the original incoming muon. The figure below shows a diagram of the experiment underwater.

Read more: The search for WIMP annihilation in the Sun | astrobites.

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