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Author Question: Why do we believe galaxy clusters are rich in dark matter? What will be an ideal ... (Read 67 times)

jayhills49

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on: Jul 27, 2018
Why do we believe galaxy clusters are rich in dark matter?
 
  What will be an ideal response?

Question 2

Why is Cygnus X-1 considered such a good black hole candidate?
 
  What will be an ideal response?


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zhanghao

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Reply #1 on: Jul 27, 2018
Answer to Question 1

Studies of the gravitational interaction of clusters reveal they have 10-100 times more mass than is visible.

Answer to Question 2

The massive visible star is pulled around by an invisible massive companion in a 5.6 day orbit. If the visible star is a giant of 30 solar masses, then the companion must be close to 10 solar masses, well over the 3 solar mass limit for black holes. Also, the matter pulled off the visible star is seen to be flowing toward the dark companion, where it generates much X-rays in the accretion disk.


jayhills49

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Reply 2 on: Jul 27, 2018
Thanks for the timely response, appreciate it

debra928

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Reply 3 on: Yesterday
Excellent

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