Composite image of an edge-on spiral galaxy with a radio halo. The large, grey-blue area is the combined radio halos of 30 different galaxies. At the center is a visible-light image of one of the galaxies, NGC 5775. Image via Jayanne English, Judith Irwin and Theresa Wiegert; CHANG-ES consortium; NRAO/AUI/NSF; NASA/STScI
Most of the light and radio waves seen from distant spiral galaxies come from objects in the galaxies’ flat disks. That’s where most of the stars, dust and gas of a spiral galaxy resides. Learning about the environment above and below galaxy disks has not been easy, but now an international team of astronomers has announced the results of a new study of the area around some nearby spiral galaxies, made possible by a decade-long upgrade of a long established radio telescope. These astronomers studied 35 nearby edge-on galaxies to learn that so-called radio halos – believed to be created by cosmic rays and magnetic fields above and below the galaxies’ disks – are much more common than previously thought.
Astronomers knew that radio halos existed. They first discovered them in 1959, and, in fact, this work confirms a prediction about such halos made in 1961. The halos themselves cannot be seen in visible light. They are large-scale areas of radio emission, studied by telescopes such as the Karl G. Jansky Very Large Array (VLA) near Socorro, New Mexico. That telescope was used in this new study, after its decade-long upgrade. As a result of the upgrade, the telescope can detect now radio emission much fainter than was previously possible. Judith Irwin, of Queen’s University in Canada, leader of the project, said in an October 13, 2015 statement from VLA:
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.
The astronomers in this project – which is called CHANG-ES – had the goals of investigating how often radio halos occur, and of understanding how an extended radio halo interacts with the visible disk of a galaxy. They didn’t answer all the questions, of course; this new study is more like a first step in opening up a whole new field of investigation.
The astronomers say that studying galactic halos with radio telescopes will let them probe a whole 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.
Along with the report on their findings released this week, the astronomers also are making their first batch of specialized VLA images available to other researchers. The data are available at: http://ift.tt/1LLHrdJ
This is a traditional radio image of a galactic halo, in this case, of the mini-halo in the Perseus galaxy cluster. Read more about this image.
Bottom line: Astronomers studied 35 nearby galaxies with a newly upgraded radio telescope in New Mexico to learn that that halos of cosmic rays and magnetic fields – above and below the disks of galaxies – are much more common than they had thought.
from EarthSky http://ift.tt/1LLHsy4
Composite image of an edge-on spiral galaxy with a radio halo. The large, grey-blue area is the combined radio halos of 30 different galaxies. At the center is a visible-light image of one of the galaxies, NGC 5775. Image via Jayanne English, Judith Irwin and Theresa Wiegert; CHANG-ES consortium; NRAO/AUI/NSF; NASA/STScI
Most of the light and radio waves seen from distant spiral galaxies come from objects in the galaxies’ flat disks. That’s where most of the stars, dust and gas of a spiral galaxy resides. Learning about the environment above and below galaxy disks has not been easy, but now an international team of astronomers has announced the results of a new study of the area around some nearby spiral galaxies, made possible by a decade-long upgrade of a long established radio telescope. These astronomers studied 35 nearby edge-on galaxies to learn that so-called radio halos – believed to be created by cosmic rays and magnetic fields above and below the galaxies’ disks – are much more common than previously thought.
Astronomers knew that radio halos existed. They first discovered them in 1959, and, in fact, this work confirms a prediction about such halos made in 1961. The halos themselves cannot be seen in visible light. They are large-scale areas of radio emission, studied by telescopes such as the Karl G. Jansky Very Large Array (VLA) near Socorro, New Mexico. That telescope was used in this new study, after its decade-long upgrade. As a result of the upgrade, the telescope can detect now radio emission much fainter than was previously possible. Judith Irwin, of Queen’s University in Canada, leader of the project, said in an October 13, 2015 statement from VLA:
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.
The astronomers in this project – which is called CHANG-ES – had the goals of investigating how often radio halos occur, and of understanding how an extended radio halo interacts with the visible disk of a galaxy. They didn’t answer all the questions, of course; this new study is more like a first step in opening up a whole new field of investigation.
The astronomers say that studying galactic halos with radio telescopes will let them probe a whole 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.
Along with the report on their findings released this week, the astronomers also are making their first batch of specialized VLA images available to other researchers. The data are available at: http://ift.tt/1LLHrdJ
This is a traditional radio image of a galactic halo, in this case, of the mini-halo in the Perseus galaxy cluster. Read more about this image.
Bottom line: Astronomers studied 35 nearby galaxies with a newly upgraded radio telescope in New Mexico to learn that that halos of cosmic rays and magnetic fields – above and below the disks of galaxies – are much more common than they had thought.
from EarthSky http://ift.tt/1LLHsy4
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