MAGIC (Major Atmospheric Gamma Imaging Cherenkov Telescopes, later renamed to MAGIC Florian Goebel Telescopes) is a system of two

Imaging Atmospheric Cherenkov telescope IACT stands for Imaging Atmospheric (or Air) Cherenkov Telescope or Technique. It is a device or method to detect very-high-energy gamma ray photons in the photon energy range of 50 GeV to 50 TeV. There are four operating IACT system ...

s situated at the

Roque de los Muchachos Observatory Roque de los Muchachos Observatory ( es, Observatorio del Roque de los Muchachos, ORM) is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands, Spain. The observatory site is operated ...

La Palma La Palma (, ), also known as ''La isla bonita'' () and officially San Miguel de La Palma, is the most north-westerly island of the Canary Islands, Spain. La Palma has an area of making it the fifth largest of the eight main Canary Islands. The ...

, one of the

Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Mo ...

, at about 2200 m above sea level. MAGIC detects particle showers released by gamma rays, using the Cherenkov radiation, i.e., faint light radiated by the charged particles in the showers. With a diameter of 17 meters for the reflecting surface, it was the largest in the world before the construction of H.E.S.S. II. The first telescope was built in 2004 and operated for five years in standalone mode. A second MAGIC telescope (MAGIC-II), at a distance of 85 m from the first one, started taking data in July 2009. Together they integrate the MAGIC telescope stereoscopic system. MAGIC is sensitive to cosmic

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nucleus, atomic nuclei. It consists of the shortest wavelength electromagnetic wav ...

s with photon energies between 50

GeV GEV may refer to: * ''G.E.V.'' (board game), a tabletop game by Steve Jackson Games * Ashe County Airport, in North Carolina, United States * Gällivare Lapland Airport, in Sweden * Generalized extreme value distribution * Gev Sella, Israeli-South ...

(later lowered to 25 GeV) and 30 TeV due to its large mirror; other ground-based gamma-ray telescopes typically observe gamma energies above 200–300 GeV. Gamma-ray astronomy also utilizes satellite-based detectors, which can detect gamma-rays in the energy range from keV up to several GeV.

Aims

The goals of the telescope are to detect and study primarily photons coming from: *Accretion of black holes in

active galactic nuclei An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not prod ...

* Supernova remnants, due to their interest as sources of

cosmic rays Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our ow ...

. *Other galactic sources such as pulsar wind nebulae or X-ray binaries. *Unidentified

EGRET Egrets ( ) are herons, generally long-legged wading birds, that have white or buff plumage, developing fine plumes (usually milky white) during the breeding season. Egrets are not a biologically distinct group from herons and have the same buil ...

or Fermi sources * Gamma ray bursts *Annihilation of

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

Observations

MAGIC has found pulsed gamma-rays at energies higher than 25 GeV coming from the

Crab Pulsar The Crab Pulsar (PSR B0531+21) is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054.magnetosphere, in contradiction with many models. In 2006 MAGIC detected very high energy cosmic rays from the

quasar A quasar is an extremely luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a mass rangin ...

3C 279 3C 279 (also known as 4C–05.55, NRAO 413, and PKS 1253–05) is an optically violent variable quasar (OVV), which is known in the astronomical community for its variations in the visible, radio and x-ray bands. The quasar was observed to hav ...

, which is 5 billion light years from Earth. This doubles the previous record distance from which very high energy cosmic rays have been detected. The signal indicated that the universe is more transparent than previously thought based on data from optical and infrared telescopes. MAGIC did not observe cosmic rays resulting from dark matter decays in the dwarf galaxy Draco. This strengthens the known constraints on dark matter models. A much more controversial observation is an energy dependence in the speed of light of cosmic rays coming from a short burst of the

blazar A blazar is an active galactic nucleus (AGN) with a relativistic jet (a jet composed of ionized matter traveling at nearly the speed of light) directed very nearly towards an observer. Relativistic beaming of electromagnetic radiation from t ...

Markarian 501 on July 9, 2005. Photons with energies between 1.2 and 10 TeV arrived 4 minutes after those in a band between 0.25 and 0.6 TeV. The average delay was 30 ±12 ms per GeV of energy of the photon. If the relation between the space velocity of a photon and its energy is linear, then this translates into the fractional difference in the speed of light being equal to minus the photon's energy divided by 2×10¹⁷ GeV. The researchers have suggested that the delay could be explained by the presence of quantum foam, the irregular structure of which might slow down photons by minuscule amounts only detectable at cosmic distances such as in the case of the blazar.

Technical specifications

Each telescope has the following specifications: *A collecting area 236 m² consisting of 956 50 cm × 50 cm

aluminium Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...

individual reflectors *A lightweight

carbon fibre Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English The use of the English language in current and former member countries of the Commonwealth of Nations was largely inherited fro ...

frame *A detector consisting of 396 separate hexagonal photomultiplier detectors in the center (diameter: 2.54 cm) surrounded by 180 larger photomultiplier detectors (diameter: 3.81 cm). *Data are transferred in analogue form by fibre optic cables *Signal digitization is done via an ADC (analog-to-digital converter) with a 2 GHz sampling rate *Total weight of 40,000 kg *Reaction time to move to any position of the sky less than 22 seconds Each mirror of the reflector is a sandwich of an aluminum

honeycomb A honeycomb is a mass of hexagonal prismatic wax cells built by honey bees in their nests to contain their larvae and stores of honey and pollen. Beekeepers may remove the entire honeycomb to harvest honey. Honey bees consume about of honey t ...

, 5 mm plate of AlMgSi alloy, covered with a thin layer of

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

to protect the mirror surface from aging. The mirrors have spherical shape with a curvature corresponding to the position of the plate in the

paraboloid In geometry, a paraboloid is a quadric surface that has exactly one axis of symmetry and no center of symmetry. The term "paraboloid" is derived from parabola, which refers to a conic section that has a similar property of symmetry. Every pla ...

reflector. The

reflectivity The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electroni ...

of the mirrors is around 90%. The focal spot has a size of roughly half a pixel size (<0.05°). Directing the telescope to different elevation angles causes the reflector to deviate from its ideal shape due to the gravity. To counteract this deformation, the telescope is equipped with Active Mirror Control system. Four mirrors are mounted on each panel, which is equipped with

actuator An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening a valve. In simple terms, it is a "mover". An actuator requires a control device (controlled by control signal) a ...

s that can adjust its orientation in the frame. The signal from the detector is transmitted over 162 m optical fibers. The signal is digitized and stored in 32 kB ring buffer. The readout of the ring buffer results in a dead time 20 µs, which corresponds to about 2% dead time at the design trigger rate of 1 kHz. The readout is controlled by an

FPGA A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturinghence the term ''Field-programmability, field-programmable''. The FPGA configuration is generally specifi ...

(

Xilinx Xilinx, Inc. ( ) was an American technology and semiconductor company that primarily supplied programmable logic devices. The company was known for inventing the first commercially viable field-programmable gate array (FPGA) and creating the fi ...

) chip on a PCI (MicroEnable) card. The data are saved to a

RAID0 In computer storage, the standard RAID levels comprise a basic set of RAID ("redundant array of independent disks" or "redundant array of inexpensive disks") configurations that employ the techniques of striping, mirroring, or parity to create la ...

disk system at a rate up to 20 MB/s, which results in up to 800 GB raw data per night.

Collaborating institutions

Physicists from over twenty institutions in Germany, Spain, Italy, Switzerland, Croatia, Finland, Poland, India, Bulgaria and Armenia collaborate in using MAGIC; the largest groups are at *Institut de Física d'Altes Energies (

IFAE The Institute for High Energy Physics (Institut de Fisica d'Altes Energies, IFAE) of Barcelona, Spain, is a Public Consortium between the Generalitat de Catalunya (Government of the Autonomous Community of Catalonia) and the Universitat Autònoma ...

), Spain * Universitat Autònoma de Barcelona,

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' ( Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...

* Universidad Complutense de Madrid, Spain *Centro de Investigaciones Energéticas, MedioAmbientales y Tecnológicas ( CIEMAT), Spain * Instituto de Astrofísica de Andalucía, Spain * Instituto de Astrofísica de Canarias, Spain *ETHZ, Zürich, Switzerland *UNIGE, Geneva, Switzerland *Dipartimento di Fisica and INFN,

University of Padua The University of Padua ( it, Università degli Studi di Padova, UNIPD) is an Italian university located in the city of Padua, region of Veneto, northern Italy. The University of Padua was founded in 1222 by a group of students and teachers from ...

, Italy * Tuorla Observatory,

Piikkiö Piikkiö (; sv, Pikis), is a former municipality of Finland. Piikkiö was consolidated with Kaarina on 1 January 2009. It is located in the province of Western Finland and is part of the Southwest Finland region. The municipality had a populati ...

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bo ...

*Dipartimento di Fisica and INFN, University of Siena, Italy *Dipartimento di Fisica and INFN,

University of Udine The University of Udine ( Italian ''Università degli Studi di Udine'') is a university in the city of Udine, Italy. It was founded in 1978 as part of the reconstruction plan of Friuli after the earthquake in 1976. Its aim was to provide the F ...

, Italy * TU Dortmund University,

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

University of Würzburg The Julius Maximilian University of Würzburg (also referred to as the University of Würzburg, in German ''Julius-Maximilians-Universität Würzburg'') is a public research university in Würzburg, Germany. The University of Würzburg is one o ...

* Max Planck Institute for Physics,

*Institute for Particle Physics,

Zürich , neighboring_municipalities = Adliswil, Dübendorf, Fällanden, Kilchberg, Maur, Oberengstringen, Opfikon, Regensdorf, Rümlang, Schlieren, Stallikon, Uitikon, Urdorf, Wallisellen, Zollikon , twintowns = Kunming, San Francisco Zürich () i ...

, Switzerland *

National Institute for Astrophysics The National Institute for Astrophysics ( it, Istituto Nazionale di Astrofisica, or INAF) is an Italian research institute in astronomy and astrophysics, founded in 1999. INAF funds and operates twenty separate research facilities, which in turn ...

(INAF), Italy * Institute for Nuclear Research and Nuclear Energy,

Sofia Sofia ( ; bg, София, Sofiya, ) is the Capital city, capital and List of cities and towns in Bulgaria, largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain in the western parts of the country. ...

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Mac ...

*Croatian MAGIC Consortium ( Institute Ruđer Bošković,

Zagreb Zagreb ( , , , ) is the capital and largest city of Croatia. It is in the northwest of the country, along the Sava river, at the southern slopes of the Medvednica mountain. Zagreb stands near the international border between Croatia and Sl ...

; University of Split, Split; University of Rijeka,

Rijeka Rijeka ( , , ; also known as Fiume hu, Fiume, it, Fiume ; local Chakavian: ''Reka''; german: Sankt Veit am Flaum; sl, Reka) is the principal seaport and the third-largest city in Croatia (after Zagreb and Split). It is located in Prim ...

Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...

References

External links