Dark matter not found in globular clusters orbiting MilkyWay

In summary: If the remaining mass is greater than the visible mass, it is assumed to be dark matter. This can be done using gravitational lensing or studying the orbital velocities of stars within the cluster.
  • #1
Gordon Potter IV
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On the podcast “Skeptics Guide to the Universe”, host, Steven Novella mentioned that astronomers can tell the difference between globular clusters orbiting the Milky Way Galaxy and satellite galaxies by looking to see if there is the gravitational effects of dark matter. Why would this be? That there is no dark matter in GC’s orbiting MW but satellite galaxies do? And isn’t this a good clue as to what dark matter may be or at least eliminate some ideas? I was unable to find any further info online, and thought this might be the right place to learn more.
Thank you
 
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  • #2
Welcome to PF.

'Dark matter' is a placeholder name for stuff which has mass like normal matter, but is not visible.
That is, it does not interact with the electromagnetic field
Enough dark matter though produces gravitational effects which have been observed.
We don't know what it is, but it's being worked on experimentally.
The wiki summary is OK.
https://en.wikipedia.org/wiki/Dark_matter
 
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  • #3
Gordon Potter IV said:
On the podcast “Skeptics Guide to the Universe”, host, Steven Novella mentioned that astronomers can tell the difference between globular clusters orbiting the Milky Way Galaxy and satellite galaxies by looking to see if there is the gravitational effects of dark matter. Why would this be?

Hi there
welcome to PF :smile:


Sorry, but that's rubbish ... globulars and galaxies are very different looking visually ... you don't need to use any other exotic method to distinguish their difference, like that guy is suggesting

regards
Dave
 
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  • #4
davenn said:
Hi there
welcome to PF :smile:


Sorry, but that's rubbish ... globulars and galaxies are very different looking visually ... you don't need to use any other exotic method to distinguish their difference, like that guy is suggesting

regards
Dave

That does not answer Gordon Potter IV's question the way I read it. Why do globular clusters lack dark matter?

I'll add the further question, "how accurately can you measure the dark matter in a globular cluster?"
 
  • #5
stefan r said:
That does not answer Gordon Potter IV's question the way I read it. Why do globular clusters lack dark matter?

That wasn't the Q

this was ...

On the podcast “Skeptics Guide to the Universe”, host, Steven Novella mentioned that astronomers can tell the difference between globular clusters orbiting the Milky Way Galaxy and satellite galaxies by looking to see if there is the gravitational effects of dark matter. Why would this be?

he never stated
Why do globular clusters lack dark matter?
that is YOUR statement
 
  • #6
stefan r said:
I'll add the further question, "how accurately can you measure the dark matter in a globular cluster?"

how can you measure something, that is still hypothetical ... accurately or otherwise ?
 
  • #7
By measuring the total mass and subtracting the mass of the stars.
 
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Likes davenn

1. What is dark matter?

Dark matter is a type of matter that is believed to make up about 85% of the total matter in the universe. It does not interact with light or other forms of electromagnetic radiation, making it invisible to telescopes. Its existence is inferred through its gravitational effects on visible matter and the structure of the universe.

2. Why is dark matter not found in globular clusters orbiting the Milky Way?

Globular clusters are groups of stars that are held together by their own gravity. These clusters are not massive enough to have significant amounts of dark matter, which is thought to only exist in larger structures like galaxies and galaxy clusters. Additionally, the dense and tightly bound nature of globular clusters makes it difficult for dark matter to be present.

3. How do scientists study dark matter?

Scientists use a variety of methods to study dark matter, including observations of its gravitational effects on visible matter, simulations of the structure of the universe, and experiments using particle accelerators. These methods help scientists understand the properties and distribution of dark matter.

4. What are the current theories about the nature of dark matter?

There are several theories about the nature of dark matter, but the most widely accepted one is the Cold Dark Matter (CDM) theory. This theory proposes that dark matter is made up of slow-moving particles that were created during the Big Bang. Other theories suggest that dark matter may be made up of primordial black holes or modified theories of gravity.

5. What are the implications of not finding dark matter in globular clusters?

The absence of dark matter in globular clusters may provide insights into the nature of dark matter and its distribution in the universe. It could also help refine current theories and potentially lead to the discovery of new particles or forces. However, more research and observations are needed to fully understand the implications of this finding.

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