Featured Research

from universities, journals, and other organizations

Heart Of A Galaxy Emits Gamma Rays

Date:
October 4, 2009
Source:
Max-Planck-Gesellschaft
Summary:
The H.E.S.S. telescope system detects high-energy rays from the starburst region of a galactic system outside the Milky Way.

Heart of a galaxy emitting gamma rays: This image taken with H.E.S.S. shows the heart of the NGC 253 galactic system. The black star marks the optical centre and the white contours indicate the shape of the galaxy. The H.E.S.S. telescope system perceives the centre of the galaxy as a point - as the comparison with a simulated artificial point source in the inset ("PSF") shows.
Credit: H.E.S.S. Collaboration

Quite a few distant galaxies turn out to be cosmic delivery rooms. Large numbers of massive stars are born in the hearts of these starburst galaxies, and later explode as supernovae. In the remnants they leave behind, particles are accelerated to very high energies. Astrophysicists have now used the H.E.S.S. telescopes to make detailed measurements of the gamma rays from the NGC 253 galaxy. As predicted, these high-energy rays originate from the region of maximum supernova activity close to the centre.

Results of the research are reported in Science Express, September 24, 2009.

At a distance of some twelve million light years away, NGC 253 is one our closest spiral galaxies outside the so-called local group of our Milky Way and its companions. Observations in the visible light as well as in the infrared and radio frequency ranges had already shown there was a small region at the centre of NGC 253 which gave birth to a very high number of stars. This region exhibits a very high density of interstellar dust and gas.

The high-mass stars born in this region use up their nuclear fuel relatively quickly and stagger into an energy crisis at the end of their life. The nucleus collapses while the star destroys itself in one final explosion. Such a supernova suddenly flares up a million or even a billion times brighter than before. The charged particles accelerated to very high energies in the remnants of such explosions react with the surrounding medium or with electromagnetic fields to generate extremely high-energy gamma quanta.

Between 2005 and 2008, astrophysicists used the H.E.S.S. telescope system in Namibia over a total observation period of 119 hours to detect the expected gamma rays at energies exceeding 220 GeV (billion electronvolts). The source of these rays lies precisely at the optical centre of NGC 253 and appears as a point to H.E.S.S. This makes it the weakest source discovered to date in the very high-energy gamma radiation range.

The flux of radiation from the starburst region of NGC 253 measured by H.E.S.S. implies an enormous cosmic ray density - more than 1,000 times higher than at the centre of the Milky Way. Moreover, the high gas density makes the conversion of cosmic rays into gamma rays around one order of magnitude more efficient. Accordingly, the central region of NGC 253 shines around five times as brightly in the light of gamma rays as all the rest of the galaxy together.

The four H.E.S.S. telescopes, each with a mirror area of 108 square metres, observe weak bluish and extremely short flashes of light. This so called Cherenkov radiation is emitted by showers of particles created when high-energy gamma quanta collide with molecules in Earth's atmosphere. H.E.S.S. stands for High Energy Stereoscopic System and has been in operation since the beginning of 2004. Since this time it has made many important discoveries, such as the first astronomical image of a supernova remnant in the high-energy gamma radiation range, or the detection of galaxies with active nuclei in the light of gamma rays. The fifth, much larger telescope that is currently under construction will significantly improve the sensitivity of the system and extend the observable energy range. The H.E.S.S. collaboration under the overall lead management of the Max Planck Institute for Nuclear Physics involves more than 150 researchers from Germany, France, Great Britain, Poland, Czech Republic, Ireland, Austria, Sweden, Armenia, South Africa and Namibia.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. F. Acero, F. Aharonian et al. Detection of Gamma Rays from a Starburst Galaxy. Science, 2009; DOI: 10.1126/science.1178826

Cite This Page:

Max-Planck-Gesellschaft. "Heart Of A Galaxy Emits Gamma Rays." ScienceDaily. ScienceDaily, 4 October 2009. <www.sciencedaily.com/releases/2009/10/091002093805.htm>.
Max-Planck-Gesellschaft. (2009, October 4). Heart Of A Galaxy Emits Gamma Rays. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/2009/10/091002093805.htm
Max-Planck-Gesellschaft. "Heart Of A Galaxy Emits Gamma Rays." ScienceDaily. www.sciencedaily.com/releases/2009/10/091002093805.htm (accessed August 1, 2014).

Share This




More Space & Time News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Study Says The Moon Was Deformed Early In Its History

New Study Says The Moon Was Deformed Early In Its History

Newsy (July 31, 2014) Scientists say when the moon was young, it was deformed by the Earth's gravitational pull, which gave it a lemon-like shape. Video provided by Newsy
Powered by NewsLook.com
Supply Ship Takes Off for International Space Station

Supply Ship Takes Off for International Space Station

AFP (July 30, 2014) The European Space Agency's fifth Automated Transfer Vehicle (ATV-5) is takes off to the International Space Station on an Ariane 5 rocket from French Guiana. Duration: 00:34 Video provided by AFP
Powered by NewsLook.com
Raw: Rocket Launches Into Space With Cargo Ship

Raw: Rocket Launches Into Space With Cargo Ship

AP (July 30, 2014) Arianespace launched a rocket Tuesday from French Guiana carrying a robotic cargo ship to deliver provisions to the International Space Station. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins