Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MAGIC discovers variable very high energy gamma-ray emission from a microquasar

19.05.2006


In a recent issue of Science Magazine, the Major Atmospheric Gamma-ray ImagingCherenkov (MAGIC) Telescope has reported the discovery of variable very high energy (VHE) gamma-ray emission from a microquasar. Microquasars are binary star systems, composed of a massive ordinary star and a compact object, which can be either a neutron star or a black hole (see Fig. 1). The stars orbit around one another and, when they are close enough, there is a transfer of matter from the massive one toward the compact object, due to gravitational attraction. This matter forms a disk around the compact object and is heated-up due to viscosity, producing X-rays. In addition, the collapse of matter from the disk into the compact object produces the ejection of jets of particles that travel in opposite directions at velocities close to the speed of light. In particular the jets contain electrons that undergo the so-called synchrotron radiation, which can be detected by radio telescopes. These jets remain among the most spectacular, yet poorly explained astrophysical phenomena. Microquasars can be considered as scaled-down versions of active galactic nuclei, or quasars. Quasars display also jets of relativistic particles, but in their case the compact object is a black hole of millions of solar masses located at the center of a galaxy. In contrast to quasars, where phenomena of jet formation and matter ejection can take years, microquasar jets evolve in time scales of days, a fact that makes them more suitable for human observations. Microquasars are also candidates to be one of the sites of production of the cosmic rays, a mystery unsolved since their discovery almosta hundred years ago.



The study of microquasars represents one of the most important additions to the recently born field of VHE gamma-ray astrophysics. VHE gamma-rays are a kind of radiation which is produced in the most violent phenomena of our Universe, like e.g. supernova explosions or quasars. They can reach the Earth, albeit at a very low rate (typically less than one gamma-ray per square meter and per week). MAGIC detects gamma-rays through the short light flashes that they produce as they enter the atmosphere. MAGIC is the largest telescope exploiting this experimental technique, with a 17 m diameter mirror. It is located at the observatory Roque de los Muchachos on the Canary Island of La Palma (Spain). The MAGIC team is composed of more than 130 scientists coming from 9 countries, namely: Spain, Germany, Italy, Switzerland, Poland, Armenia, Finland, Bulgaria and USA.

MAGIC has observed, between October 2005 and March 2006, one of the approximately 20 known microquasars, called LS I +61 303. VHE gamma-rays coming from LS I +61 303 have been detected at an approximate rate of one gamma-ray per square meter and per month. Only one other binary star system (LS 5039) is known to emit VHE gamma-rays. This new discovery points to the fact that gamma-ray production could be a common property of microquasars. The results of the MAGIC team have revealed a very interesting property: the intensity of the gamma-ray emission coming from LS I +61 303 varies with time (see Fig. 2). The binary system was observed at different 2 moments along the orbital cycle of the compact object around the massive star. The time scale of variability was similar to the orbital period, showing that the VHE emission is directly related to the interplay between the two stars of the system. Furthermore, some theorists expected the gamma-ray emission to happen when the two stars are closest to one another (i.e. at periastron passage, Fig. 2a) since it is at this moment when the particles accelerated in the jet find the largest density of potential targets to produce the gammarays. However, a relatively strong gamma-ray flux was observed only when the compact object had completed about one third of the whole orbital cycle (Fig 2b). Future observations of LS I +61 303 with MAGIC, together with theoretical interpretation of the present results will help elucidate the mechanisms of gamma-ray production and absorption in microquasars and in objects displaying relativistic jets in general.

Lucas Santos Botana | alfa
Further information:
http://magic.ifae.es/LSI
http://www.uab.es

More articles from Physics and Astronomy:

nachricht Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

IHP presents the fastest silicon-based transistor in the world

05.12.2016 | Power and Electrical Engineering

InLight study: insights into chemical processes using light

05.12.2016 | Materials Sciences

High-precision magnetic field sensing

05.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>