Gamma-ray astronomy at low energies with high sensitivity

The MAGIC Collaboration has built in 2001–2003 a first large atmospheric imaging Cherenkov telescope, MAGIC-I, with a mirror surface of 236 sq.m. and equipped with photomultiplier tubes of optimal efficiency. In 2009, a second telescope of essentially the same characteristics was added; MAGIC-II was installed at a distance of 85m from MAGIC-I. With the accent of these instruments on large mirror surface and best light collection, cosmic gamma-rays at an energy threshold lower than any existing or planned terrestrial gamma-ray telescope have become accessible. So far achieved has been a threshold of 25 GeV.

Latest news

MAGIC detects a huge VHE flare from the flat spectrum radio quasar 4C +21.35 – In a recent Astronomer's Telegram, the MAGIC collaboration reports the detection of a gamma-ray outburst from the Flat Spectrum Radio Quasar 4C +21.35, located at a redshift of z=0.432. The observation was performed in stereoscopic mode during low intensity moon light using the two 17m diameter imaging Cherenkov telescopes on La Palma, Canary Islands, Spain. During only 0.5 hours on June 17, 2010, preliminary results indicate a significant gamma-ray signal of 120 excess events corresponding to >8 sigma level above the background. The integral flux for gamma-rays with energies above 100 GeV is estimated to be at >30% of the Crab nebula flux. MAGIC will continue to observe 4C +21.35. Issued as Astronomical Telegram #2684 on 19 June 2010. MAGIC and VERITAS detect dramatic flaring of the giant radio galaxy M87 at an unprecedented flux level – M87 is being observed in a coordinated effort in 2010 by the ground-based VHE gamma-ray observatories VERITAS and MAGIC; this effort is a continuation of the joint monitoring program which was initiated by VERITAS, MAGIC, and HESS in 2008. An increasing VHE gamma-ray flux level has been measured over several nights starting on 2010-04-05, reaching a historic high state of about 20% of the flux of the Crab Nebula during the observations on 2010-04-09. This flare follows a state of low average VHE flux from M87 over the past few months after a flare was reported by MAGIC earlier in 2010. Issued as Astronomical Telegram #2542 on 9 April 2010. MAGIC detects VHE gamma-ray emission from IC 310 – On March 25, 2010, the MAGIC Collaboration reported the discovery of VHE gamma-ray emission from the new source MAGIC J0317+413. The source was in the field of view of the MAGIC telescopes between October 2009 and February 2010. The emission position is consistent with the head-tail radio galaxy IC310 (z=0.0189) located in the outer region of the Perseus cluster of galaxies. A gamma-ray signal with a significance corresponding to more than 6 standard deviations was obtained from 20 hours taken in stereoscopic observation mode. An analysis of 38 hours of single telescope observations performed from 2008 to 2010 has confirmed the detection at ~6 sigma significance. Preliminary analysis indicates emission at the level of ~2.5% of the Crab Nebula flux above 300 GeV. The source was also recently detected in Fermi/LAT data. Issued as Astronomical Telegram #2510 on 25 March 2010.

The giant radio galaxy Messier 87 (upper left corner) and the 17-meter MAGIC gamma-ray telescope on the Canary island of La Palma. Picture credit: NASA; Hubble Heritage Team (STScI/AURA); R.Wagner (MPI für Physik).

MAGIC status

Located on a mountain top on the Canary island of La Palma, the construction of this world-wide largest telescope (MAGIC-I) has been completed in 2003. Fully operational since 2004, it is run by an international collaboration of 17 institutes (see MAGIC Collaboration). A second telescope, MAGIC-II, on the same site, has been completed and is presently (mid-2009) in the commissioning phase. In large parts, it is a copy of MAGIC-I, but has a more homogeneous camera with more pixels, and a refurbished readout.

The first light ceremony of the MAGIC-II telescope took place on 2009 April 24-25. MAGIC-II is located at a distance of 85 m from the first MAGIC telescope, which has been in operation since 2004. It is expected that the stereo operation of both telescopes will increase the sensitivity of the observatory by ~3 times. For this occasion, a half-day scientific seminar on the MAGIC Project was organized in La Palma on 24 April 2009. The First Light ceremony at the MAGIC site took place in the morning of 25 April 2009. Some of the echos in the press and the material prepared for journalists can be found here.

MAGIC goals and results

All major results from MAGIC observations are summarized and recorded in the pages latest news , or, more detailed, in the publications pages. The various objects that constitute the hunting ground for Cherenkov telescopes are outlined below, with references to desriptions of MAGIC results.

Artist's view of an Active Galactic Nucleus

Active galactic nuclei (AGNs) are extragalactic compact regions, typically supermassive black holes, in the centre of galaxies. They exhibit high luminosity over most of the electromagnetic spectrum. The observed radiation from AGNs comes from the accretion of matter onto a disk surrounding the black hole. The disk typically rotates, and develops jets along the axis of rotation. Inside the jet, particles are accelerated to relativistic velocities. AGN are the most luminous persistent sources of electromagnetic radiation in the universe. Blazars are AGNs with their jet pointing in the general direction of the Earth. They are characterized by rapid variability. Many blazars show superluminal features in the jet close to the source, probably due to relativistic shock fronts. Several recent MAGIC observations concern blazars: BL Lacertae, the source which gave its name to an entire subclass of blazars, Markarian 501, one of the first blazars to be seen in high-energy gamma-rays, and a scan over several potential sources. Some blazar observations also are interesting for special properties of the source. Particularly distant objects, for instance, can serve to study the absorption properties of the space between the source and our galaxy. See more below under 'Cosmology'.

Binary systems are made of a heavy star and a black hole accreting mass from its companion. They are known for the powerful emission of temporally and spectrally variable X-ray radiation. MAGIC has detected a rapidly varying signal from a known binary system, the source Cygnus X-1. This is the first detection of gamma-rays of very high energy emitted from a black hole of stellar mass. Find more details on the Cyg X-1 detection in the recent MAGIC results. An earlier result, published in 2006 in Science Magazine, concerns the detection of gamma-rays with some clear signs of periodicity from the binary system LSI +61 303. That source is visible only in a short window of phase, and the maximum in gamma-rays does not coincide with the maximum observed in periodic radio outbursts.

An X-ray binary system

A Supernova remnant: Kepler's supernova SN1604 seen in X-rays by Chandra

Supernova remnants (SNRs) are typically shell-shaped expanding remains caused by a supernova; a supernova is the final explosion of a massive star, of more than eight solar masses. It causes a brief burst of radiation that may outshine the entire host galaxy, before fading from view over several weeks or months. During this short interval, a supernova can radiate as much energy as the Sun would emit over 10 billion years. The explosion expels much or all of a star's material at high velocity, driving a shock wave into the surrounding interstellar medium, where it sweeps up an expanding shell of gas and dust called a supernova remnant. Find more details of the MAGIC-observed supernova (Cassiopea A) in the recent MAGIC results.

Cosmology: Some basic questions about the basic properties of the Universe, and its history, may also find at least partial answers in observations made by Cherenkov telescopes. The sky seen in gamma-rays could provide some major surprises. Like, for instance, in Dark Matter. From multiple measurements of galaxy movements it looks very likely that Dark Matter, matter that does not interact other than by the gravitational force, makes up a large fraction of the matter in the Universe, five or six times more than ordinary observable matter. If Dark Matter annihilates into gamma-rays, as some theories predict, then the MAGIC telescope could be the first telescope to detect them. First MAGIC observations of the dwarf galaxy Draco, which is a candidate source for Dark Matter, did set an upper limit for a signal; for more details, see the Draco results in recent MAGIC results. Or there is the intergalactic space: MAGIC has observed the most distant gamma-ray emitters known, 3C 279 and 1ES 1011. Due to their large distances, such sources permit to extract information about the space separating the source from our galaxy. And, due to the billions of years the light from such sources has taken to reach us, even information about the evolution of space may be obtained. Finally, there is Quantum Gravity: A very special possibility was offered by observation of a short outburst of the blazar Markarian 501. which seems to show some energy dependence of gamma arrival times, permitting speculations about possible quantum gravity effects.

A simulation of the filament-like distribution of Dark Matter in the Universe

New objects: A new source of very high energy gamma-ray emission was detected by MAGIC, located close to the Galactic Plane, coincident with the supernova remnant IC443. It has been named MAGIC J0616+225. The emission could be related to the molecular environment found in the region of IC443. For more details on J0616, look in the recent MAGIC results. A finding of some serendipity is the source that MAGIC discovered near Cygnus X-3. Due to their small opening angle, Cherenkov telescopes do not usually see signals that have not been conjectured previously by observations at other wavelengths. In this case, the discovered object is near Cygnus X-3, and it is in studying this well-known X-ray source that this (unidentified and presently unclassifyable) object was seen. For more details, see the Cyg X-3 results in recent MAGIC results.

MAGIC observations near Cygnus X-3

Job Opportunities

• Some institutes collaborating in MAGIC have individual job openings. Follow the institute links in the list of collaborators

MAGIC aspects

Experience an interactive panoramic tour of MAGIC (March 2008: the MAGIC-II telescope is under construction),

or listen to the cosmic voice of MAGIC,

or inspect a small collection of early raw data: images from early MAGIC events (2003 / 2004).

More Information on MAGIC:

• An introduction to the MAGIC Telescope
• Some information on the MAGIC Telescope site
• More about imaging atmospheric Cherenkov telescopes
• Technology and performance aspects
• Recent results

BMBF = Bundesministerium für Bildung und Forschung (Germany)
MPG = Max-Planck-Gesellschaft (Germany)
INFN = Istituto Nazionale di Fisica Nucleare (Italy)
MCI = Ministerio de Ciencia e Innovacion (Spain)
SNF = Swiss National Science Foundation (Switzerland)