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 SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>