HEAPOW: Chandra XX: Whirlpool Bath (2019 Aug 26)

[bystander]

HEAPOW: Chandra XX: Whirlpool Bath (2019 Aug 26)

The high-resolution pictures of the X-ray sky obtained by the Chandra X-ray Observatory over the past 20 years have helped revolutionize our knowledge of the high-energy Universe. Chandra's images allow astronomers to disentangle emission from crowded regions and get a better understanding of the population of black holes, neutron stars and flaring sources distributed through space. An excellent example is the Chandra X-ray image of the Whirlpool Galaxy, a grand design spiral galaxy in the constellation of Canes Venatici (the "hunting dog"). Because the Whirlpool is only 30 million lightyears away from us, and we view it face-on, we can study the structure of the Whirlpool in detail, and learn about the structure of spiral galaxies and the processes that shape them. The Whirlpool is also merging with a smaller neighbor galaxy, seen to the left of the image, and so offers astronomers the opportunity to understand how such galaxy-galaxy interactions work. The Chandra X-ray image is shown above in purple, and is superimposed on an optical image from the Hubble Space Telescope. The Chandra image has an exposure time of over 1 million seconds making it the deepest, clearest X-ray image of the Whirlpool yet obtained. It shows how hot diffuse gas produced by extremely energetic processes like supernovae explosions permeates the spiral arms, and has allowed astronomers to identify over 500 individual sources of X-rays in the Whirlpool (about a factor of five more than previously known). Most of the identified sources turn out to be X-ray emitting binary stars composed of compact neutron stars stripping material from a either a low- or high-mass normal companion star, while others are binaries composed of accreting black holes. This X-ray/optical comparison helps show how high-energy processes like supernovae and shock waves help shape spirals galaxies like our own Milky Way.

CXC: M51: Chandra Captures Galaxy Sparkling in X-rays
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Author: Dr. Michael F. Corcoran

[Ann]

HEAPOW/Chandra XX wrote:

The Chandra X-ray image is shown above in purple, and is superimposed on an optical image from the Hubble Space Telescope. The Chandra image has an exposure time of over 1 million seconds making it the deepest, clearest X-ray image of the Whirlpool yet obtained. It shows how hot diffuse gas produced by extremely energetic processes like supernovae explosions permeates the spiral arms

The false color purple glow of X-rays doesn't permeate all of the spiral arms of M51. The spiral arms at top at bottom contain discrete X-ray sources, but no diffuse purple glow. The cores of both M51 and the galaxy it is colliding with, NGC 5195, are aglow with purple light.

Why do some parts of M51 lack this "ambient glow", and why is this glow present in other parts of M51 and its neighbour galaxy?

Ann

[BDanielMayfield]

HEAPOW/Chandra XX wrote:

The Chandra X-ray image is shown above in purple, and is superimposed on an optical image from the Hubble Space Telescope. The Chandra image has an exposure time of over 1 million seconds making it the deepest, clearest X-ray image of the Whirlpool yet obtained. It shows how hot diffuse gas produced by extremely energetic processes like supernovae explosions permeates the spiral arms

The false color purple glow of X-rays doesn't permeate all of the spiral arms of M51. The spiral arms at top at bottom contain discrete X-ray sources, but no diffuse purple glow. The cores of both M51 and the galaxy it is colliding with, NGC 5195, are aglow with purple light.

Why do some parts of M51 lack this "ambient glow", and why is this glow present in other parts of M51 and its neighbour galaxy?

Ann

The simplest answer (therefore the the only one I can think of ) is that the diffuse glow is from expanding SN remnants which cover large areas, whereas discrete point sources are the binaries with hot accretion disks. It must have been a long time since there were SN in the areas lacking "ambient glow".

Bruce

[Ann]

HEAPOW/Chandra XX wrote:

The Chandra X-ray image is shown above in purple, and is superimposed on an optical image from the Hubble Space Telescope. The Chandra image has an exposure time of over 1 million seconds making it the deepest, clearest X-ray image of the Whirlpool yet obtained. It shows how hot diffuse gas produced by extremely energetic processes like supernovae explosions permeates the spiral arms

The false color purple glow of X-rays doesn't permeate all of the spiral arms of M51. The spiral arms at top at bottom contain discrete X-ray sources, but no diffuse purple glow. The cores of both M51 and the galaxy it is colliding with, NGC 5195, are aglow with purple light.

Why do some parts of M51 lack this "ambient glow", and why is this glow present in other parts of M51 and its neighbour galaxy?

Ann

The simplest answer (therefore the the only one I can think of ) is that the diffuse glow is from expanding SN remnants which cover large areas, whereas discrete point sources are the binaries with hot accretion disks. It must have been a long time since there were SN in the areas lacking "ambient glow".

Bruce

Yes, it's highly likely that the diffuse X-ray emission in parts of M51 emanates from supernova remnants. Consider the "two-faced" X-ray nature of giant emission nebula in spiral galaxy M33.

Click to view full size image

NGC 604. Credit:
X-ray: NASA / CXC / R. Tuellmann (Harvard-Smithsonian CfA) et al.
Optical: NASA/AURA/STScI

APOD Robot wrote about the picture of NGC 604:

Intriguingly, NGC 604 itself is divided by a wall of relatively cool gas. On the western (right) side of the nebula, measurements indicate that material is likely heated to X-ray temperatures by the energetic winds from a cluster of about 200 young, massive stars. On the eastern side the X-ray filled cavities seem to be older, suggesting supernova explosions from the end of massive star evolution contribute to their formation.

So one half of NGC 604 contains X-rays from energetic winds from 200 young, massive stars, but the other half contains X-rays from supernova remnants. It is probable that the presence or absence of a diffuse X-ray glow in different parts of M51 also has to do with the presence or absence of (many) supernova remnants.

Ann