Bullet_Cluster

[David Levy]

https://en.wikipedia.org/wiki/Bullet_Cluster

It is stated:

 

"The Bullet Cluster (1E 0657-558) consists of two colliding clusters of galaxies. Strictly speaking, the name Bullet Clusterrefers to the smaller subcluster, moving away from the larger one. It is at a co-moving radial distance of 1.141 Gpc (3.7 billion light-years).^[2]

 

"The Bullet Cluster provides the best current evidence for the nature of dark matter^[4][8] and provides "evidence against some of the more popular versions of Modified Newtonian Dynamics (MOND)" as applied to large galactic clusters"

 

"At a statistical significance of 8σ, it was found that the spatial offset of the center of the total mass from the center of the baryonic mass peaks cannot be explained with an alteration of the gravitational force law alone.^[10]

 

Questions:
1. How the science could estimate the exact location of the spatial offset center of the total mass? (Is it by lensing?)

2. Total mass – does it mean the dark Matter + Baryonic mass? If so, what is the expected ratio between the two?
3. Do we have any idea about the Supper massive black hole mass in each Galaxy? (There are 40 Galaxies)

4. Could it be that the B.H have some impact on that change of the spatial offset (and not just the dark matter)?

Edited April 30, 2016 by David Levy

[imatfaal]

1. Yes - basically

2. It is far from crucial for the experiment - I would expect that they used results / calculations from highly studied similar clusters. The point of this observation is not the ratio it is the separation.

3. Are Supper Massive Black holes the sort that you eat in in the evening. The mass of the black holes of each cluster will be very very small. If as I expect they used current best estimates for mass of cluster etc then possibly these best estimates will have treated BH mass distinctly but I rather doubt it. The mass portion would be around one part in a million - that's like worrying about a paperclip's mass affecting your cars acceleration.

4. No. The mass and external interaction of a black hole is well understood (whatever you may believe). Black holes will interact with each other - very spectacularly; surely you saw all the news about the gravitational waves discovery caused by merging black holes. To an extent (which is very small) the baryonic mass and blackholes will bump into each other and the dark matter will not - this is the very simplistic explanation of why you get a separation of the local of the total mass and the location of the baryonic

[Strange]

1. How the science could estimate the exact location of the spatial offset center of the total mass? (Is it by lensing?)

 

Yes. That is what the reference says.

https://arxiv.org/abs/astro-ph/0608407

 

2. Total mass – does it mean the dark Matter + Baryonic mass? If so, what is the expected ratio between the two?

 

Yes, that is what I understand total mass to mean. (Note that there are three components discussed: the mass of the stars, the mass of the plasma and the dark matter.)

 

The paper may say what proportion of the mass is estimated to be dark matter (I haven't read it).

 

3. Do we have any idea about the Supper massive black hole mass in each Galaxy? (There are 40 Galaxies)

4. Could it be that the B.H have some impact on that change of the spatial offset (and not just the dark matter)?

 

I doubt there is any information about black holes. And I doubt they would be significant. The mass is typically 0.01% of the mass of the galaxy. (Edit: and as imatfaal says, they will move with the visible components of the galaxy.)

Edited April 30, 2016 by Strange

[David Levy]

Thanks