Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Listening to the Extragalactic Radio

13.10.2015

CHANG-ES brings together scientists from all over the globe in order to investigate the occurrence and origin of radio halos, to probe the disk-halo interface, and to study in-disk emission as well as their magnetic fields and the cosmic rays illuminating these fields. The goal is to understand connections between radio halos and the host disk and its environment. A number of German scientists are co-authors in a recent study reporting observations of a sample of 35 nearby edge-on galaxies with the Karl G. Jansky Very Large Array (VLA). A median image constructed from stacking 30 observations of galaxies reveals the extent of the galaxy that is otherwise invisible in optical wavelengths.

A study of spiral galaxies seen edge-on has revealed that "halos" of cosmic rays and magnetic fields above and below the galaxies' disks are much more common than previously thought.


Composite image of an edge-on spiral galaxy with a radio halo. The large, grey-blue area is a single image formed by combining the radio halos of 30 different galaxies, as seen with the VLA.

Jayanne English (U. Manitoba), with support from Judith Irwin and Theresa Wiegert (Queen’s U.) for the CHANG-ES consortium; NRAO/AUI/NSF; NASA/STScI.

An international team of astronomers used the Karl G. Jansky Very Large Array (VLA) to study 35 edge-on spiral galaxies at distances from 11 million to 137 million light-years from Earth. The study took advantage of the ability of the VLA, following completion of a decade-long upgrade project, to detect radio emission much fainter than previously possible.

"We knew before that some halos existed, but, using the full power of the upgraded VLA and the full power of some advanced image-processing techniques, we found that these halos are much more common among spiral galaxies than we had realized," says Judith Irwin, of Queen's University in Canada, leader of the project.

Spiral galaxies, like our own Milky Way, have the vast majority of their stars, gas, and dust in a flat, rotating disk with spiral arms. Most of the light and radio waves seen with telescopes come from objects in that disk. Learning about the environment above and below such disks has been difficult.

"Studying these halos with radio telescopes can give us valuable information about a wide range of phenomena, including the rate of star formation within the disk, the winds from exploding stars, and the nature and origin of the galaxies' magnetic fields," says Theresa Wiegert, also of Queen's University, lead author of a paper in the Astronomical Journal reporting the team's findings. The paper provides the first analysis of data from all 35 galaxies in the study.

“We have studied the extended halos of individual galaxies for quite some time”, explains Ralf-Jürgen Dettmar from Ruhr-University in Bochum, Germany. “The CHANG-ES sample will provide an additional statistical access to the important question of galactic feedback.” One of his prime research targets, NGC 5775, was used as template in order to represent the inner star forming region of spiral galaxies in Fig. 1.

To see how extensive a "typical" halo is, the astronomers scaled their images of 30 of the galaxies to the same diameter, then another of the authors, Jayanne English, of the University of Manitoba in Canada, combined them into a single image. The result, says Irwin, is "a spectactular image showing that cosmic rays and magnetic fields not only permeate the galaxy disk itself, but extend far above and below the disk."

The combined image, the scientists said, confirms a prediction of such halos made in 1961.

Along with the report on their findings, the astronomers also are making their first batch of specialized VLA images available to other researchers. In previous publications, the team described the details of their project and its goals. The team has completed a series of VLA observations and their latest paper is based on analysis of their first set of images. They now are analyzing additional datasets, and also will make those additional images available to other scientists when they publish the results of the later analyses.

"The results from this survey will help answer many unsolved questions in galactic evolution and star formation", concludes Marita Krause of the Max-Planck Institute für Radioastronomie in Bonn, Germany.


The research team comprises Philip Schmidt, Silvia Carolina Mora, Ancor Damas-Segovia, Marita Krause & Rainer Beck (all Max-Planck-Institut für Radioastronomie, Bonn, Germany), Theresa Wiegert, the lead author, Judith Irwin, Stephen MacGregor & Amanda DeSouza (all Dept. of Physics, Engineering Physics & Astronomy, Queen’s University, Kingston, Canada), Arpad Miskolczi, Yelena Stein, Ralf-Jürgen Dettmar, Marek Wezgowiec (all Astronomisches Institut, Ruhr-Universität Bochum, Germany), Jayanne English (Department of Physics and Astronomy, University of Manitoba, Winnipeg, Canada), Richard J. Rand, Isaiah Santistevan (Dept. of Physics and Astronomy, University of New Mexico, Albuquerque, USA), Rene Walterbos (Dept. of Astronomy, New Mexico State University, Las Cruces, USA), Amanda Kepley (NRAO, Charlottesville, USA) , Q. Daniel Wang (Dept. of Astronomy, University of Massachusetts, Amherst, USA), George Heald (ASTRON, Dwingeloo, The Netherlands), Jiangtao Li (Dept. of Astronomy, University of Michigan, Ann Arbor, USA), Megan Johnson (CSIRO, Epping, Australia), Andrew W. Strong (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany), Troy A. Porter (Hansen Experimental Physics Laboratory, Stanford University, USA).

This work was supported by the Natural Sciences and Engineering Research Council of Canada, and the National Radio Astronomy Observatory (NRAO), which is run by the National Science Foundation (NSF).

The work at Ruhr-University Bochum, Germany, has been supported by DFG through FOR1048. The support of the Computer Center of the Max-Planck Institute (RZG) in Garching, Germany, for the use of archiving facilities is acknowledged.

Original Paper:

“CHANG-ES IV: Radio continuum emission of 35 edge-on galaxies observed with the Karl G. Jansky Very Large Array in D-configuration”, by T. Wiegert et al., 2015, The Astronomical Journal, Volume 150, Issue 3, article id. 81, 23 pp. (2015):
http://iopscience.iop.org/article/10.1088/0004-6256/150/3/81

See also: http://de.arxiv.org/abs/1508.05153

Local Contact:

Dr. Marita Krause,
Max-Planck-Institut für Radioastronomie, Bonn.
Fon: +49-228-525-312
E-mail: mkrause@mpifr-bonn.mpg.de

Dr. Rainer Beck,
Max-Planck-Institut für Radioastronomie, Bonn.
Fon: +49-228-525-323
E-mail: rbeck@mpifr-bonn.mpg.de

Dr. Norbert Junkes,
Press and Public Outreach,
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-399
E-mail: njunkes@mpifr-bonn.mpg.de

Weitere Informationen:

http://www.mpifr-bonn.mpg.de/pressreleases/2015/7

Norbert Junkes | Max-Planck-Institut für Radioastronomie

More articles from Physics and Astronomy:

nachricht Pulses of electrons manipulate nanomagnets and store information
21.07.2017 | American Institute of Physics

nachricht Vortex photons from electrons in circular motion
21.07.2017 | National Institutes of Natural Sciences

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: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>