APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

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APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by APOD Robot » Wed Nov 04, 2020 5:05 am

Image Fifty Gravitational Wave Events Illustrated

Explanation: Over fifty gravitational wave events have now been detected. These events mark the distant, violent collisions of two black holes, a black hole and a neutron star, or two neutron stars. Most of the 50 events were detected in 2019 by the LIGO gravitational wave detectors in the USA and the VIRGO detector in Europe. In the featured illustration summarizing the masses of the first 50 events, blue dots indicate higher-mass black holes while orange dots denote lower-mass neutron stars. Astrophysicists are currently uncertain, though, about the nature of events marked in white involving masses that appear to be in the middle -- between two and five solar masses. The night sky in optical light is dominated by nearby and bright planets and stars that have been known since the dawn of humanity. In contrast, the sky in gravitational waves is dominated by distant and dark black holes that have only been known about for less than five years. This contrast is enlightening -- understanding the gravitational wave sky is already reshaping humanity's knowledge not only of star birth and death across the universe, but properties of the universe itself.

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Re: APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by daddyo » Wed Nov 04, 2020 6:35 am

Interesting, I like the chandelier effect.

Seems to show the increased likelihood of higher masses merging than lower, but also that similar masses seem to be more likely to merge. Maybe it's because it's easier to detect similar or higher mass mergers. The last think I noticed is that most mergers come from similarly unequal masses, e.g. one pre-merger body is typically 50% larger than it's companion.

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Re: APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by mcfrank0 » Wed Nov 04, 2020 11:49 am

What is the significance of the X-Axis? It's not explained either here or at the source site. It doesn't appear to be time, and I don't believe it to be completely for aesthetic reasons <grin>.

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Re: APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by E Fish » Wed Nov 04, 2020 1:59 pm

mcfrank0 wrote:
Wed Nov 04, 2020 11:49 am
What is the significance of the X-Axis? It's not explained either here or at the source site. It doesn't appear to be time, and I don't believe it to be completely for aesthetic reasons <grin>.
There doesn't appear to be an x-axis, really. So maybe they're just spreading them out so that the variety of masses can be seen instead of all lumped together.

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Re: APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by neufer » Wed Nov 04, 2020 8:14 pm

daddyo wrote:
Wed Nov 04, 2020 6:35 am

Seems to show the increased likelihood of higher masses merging than lower, but also that similar masses seem to be more likely to merge. Maybe it's because it's easier to detect similar or higher mass mergers. The last think I noticed is that most mergers come from similarly unequal masses, e.g. one pre-merger body is typically 50% larger than it's companion.
https://en.wikipedia.org/wiki/Chirp_mass wrote:
<<In astrophysics the chirp mass of a compact binary system determines the leading-order orbital evolution of the system as a result of energy loss from emitting gravitational waves. In gravitational wave data analysis it is easier to measure the chirp mass than the two component masses alone. The chirp mass may be expressed in terms of the total mass of the system and the mass ratio q = m1 / m2:

Code: Select all

q	chirp mass/total mass
---------------------
1	 0.435
3	 0.366
10	 0.224
30	 0.125
100	 0.062
Black Hole mergers can be observed ~100 times further away than neutron star mergers.
  • This corresponds to a volume a million times larger :!:
    -----------------------------------------------------------
    The most distant BH event GW190521
    • Distance: 5,300 megaparsecs
      Chirp mass: 32 M
    -----------------------------------------------------------
    Neutron star event GW170817
    • Distance: 40 megaparsecs
      Chirp mass: ~0.04 M
    -----------------------------------------------------------
Art Neuendorffer

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Re: APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by MarkBour » Wed Nov 04, 2020 8:37 pm

daddyo wrote:
Wed Nov 04, 2020 6:35 am
Interesting, I like the chandelier effect.

Seems to show the increased likelihood of higher masses merging than lower, but also that similar masses seem to be more likely to merge. Maybe it's because it's easier to detect similar or higher mass mergers. The last think I noticed is that most mergers come from similarly unequal masses, e.g. one pre-merger body is typically 50% larger than it's companion.
I do find this rather unexpected as a statistical sample. It may be that LIGO/VIRGO turn out to be a sort of band-pass filter in their capabilities. Sorry, I know just enough to be dangerously wrong in this. But I'm curious as to what this data will look like over time. I had no idea they had had this many observations to date. And this may be a selected set of what they've seen ... just picked out the detection events they're interested in.
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Re: APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by bystander » Wed Nov 04, 2020 9:35 pm

E Fish wrote:
Wed Nov 04, 2020 1:59 pm
mcfrank0 wrote:
Wed Nov 04, 2020 11:49 am
What is the significance of the X-Axis? It's not explained either here or at the source site. It doesn't appear to be time, and I don't believe it to be completely for aesthetic reasons <grin>.
There doesn't appear to be an x-axis, really. So maybe they're just spreading them out so that the variety of masses can be seen instead of all lumped together.
It's an infographic, not a graph.
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alive to the gentle breeze of communication, and please stop being such a jerk.
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Re: APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by MarkBour » Thu Nov 05, 2020 1:38 am

neufer wrote:
Wed Nov 04, 2020 8:14 pm
I love their notation choice for chirp mass! This calligraphic "M", looks like a combination of a written (quarter) note and a following wave segment.

A slight improvement might be to denote chirp mass as:
Capture4.png


Since first there is a wave of increasing amplitude, and then at the end one is left with the sensation of a particular note.
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Re: APOD: Fifty Gravitational Wave Events... (2020 Nov 04)

Post by neufer » Sun Nov 08, 2020 1:42 pm

neufer wrote:
Wed Nov 04, 2020 8:14 pm
Click to play embedded YouTube video.
MarkBour wrote:
Thu Nov 05, 2020 1:38 am

I love their notation choice for chirp mass! This calligraphic "M", looks like a combination of a written (quarter) note and a following wave segment.



A slight improvement might be to denote chirp mass as:

Since first there is a wave of increasing amplitude, and then at the end one is left with the sensation of a particular note.
Art Neuendorffer