Thermalized components/virialized

  • Context: Graduate 
  • Thread starter Thread starter ChrisVer
  • Start date Start date
Click For Summary

Discussion Overview

The discussion centers on the concepts of thermalization and virialization of particle components, particularly in the context of cold dark matter (CDM) within galactic halos. Participants explore the definitions, implications, and processes involved in these phenomena.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant seeks clarification on the meanings of thermalized and virialized components in galactic halos, questioning the processes involved in thermalization and the differences between virialized and unvirialized states.
  • Another participant suggests that the Wikipedia article on the virial theorem may provide helpful context, particularly its application in astrophysics.
  • A different participant notes that the article discusses statistical dispersion in velocities related to gravitational potential but does not clarify the distinctions between thermalized/non-thermalized or virialized/unvirialized states, nor does it explain how transitions occur.
  • One participant posits that a galaxy will eventually reach a state described by the virial theorem over time, but acknowledges that significant disturbances, such as galaxy mergers, can prevent this description from being applicable.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the definitions and processes of thermalization and virialization, indicating that multiple competing views remain without a clear consensus.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the processes of thermalization and virialization, as well as the lack of clarity on how these states are defined and transitioned between.

ChrisVer
Science Advisor
Messages
3,372
Reaction score
465
I am trying to understand what does someone mean when he or she says that a particle component (eg for CDM) is thermalized/virialized in the galactic halo...
What happens during thermalization and what's the difference between virialized/unvirialized components?

Thanks...
 
Space news on Phys.org
The Wikipedia page on the virial theorem may help, particularly the section on "in astrophysics".
 
  • Like
Likes   Reactions: ChrisVer
I think that the wiki article is just referring to the fact that matter in galaxies subject to gravitational potential, can have some statistical dispersion in velocities (the sigma), and this is related to the gravitational potential...

However it doesn't make any distinction between thermalized/non-thermalized or virialized/unvirialied or how the transition is being happening...

In case you have some cloud of CDM in the galactic halo, is that cloud virialized or not? If it is not thermalized, how does it get thermalized?
 
The idea is that over time, a galaxy will eventually relax into a state that follows the virial theorem. But when there has been a significant recent disturbance (e.g. a merger between similar-sized galaxies), the galaxy is not well-described by the virial theorem at all.
 
  • Like
Likes   Reactions: ChrisVer

Similar threads

  • · Replies 53 ·
2
Replies
53
Views
7K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 24 ·
Replies
24
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 26 ·
Replies
26
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
Replies
6
Views
1K