When can globular clusters be considered collisionless?

AI Thread Summary
Globular clusters are generally considered collisional, especially in their inner regions, which raises questions about the applicability of collisionless dynamics software for their study. The discussion focuses on using such software to analyze global properties like luminosity and velocity dispersion, particularly for clusters with long relaxation times, such as NGC 2419. The term "legal" in this context refers to the appropriateness of using collisionless models without violating scientific principles. Participants suggest that while some clusters may allow for this approach, careful consideration of conditions is necessary. Recommendations for suitable software that can run on a single high-performance PC are also sought.
kderakhshani
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Hi all.

I'd like to use a software package, that has been designed for collisionless dynamics, to investigate general globular clusters. As they are highly collisional, at least in their inner parts, this perhaps makes no sense.

However, it may be meaningful for some time- or length-scales or to obtain their global properties, such as luminosity, velocity dispersion, etc.

Do you have any idea?

If that is anyway illegal, what software do you suggest that can be run on a single high-performance PC?
( I mean without having PC clusters, GPUs, GRAPE, supercomputers, etc.)

Thanks a lot.
 
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Are you asking us to suggest a software package to you?
 
The code I used for some globular cluster (NGC 2419) was NMODY, which had been written for COLLISIONLESS stellar systems. For NGC 2419 it is legal, cause its relaxation time is very long (longer than the Hubble time). (K.Derakhshani, ApJ, 783, 48, 2014)

Now, I want to use it (or some other collisionless code) for the total range of Galactic globular clusters.

Under what conditions (if any) will this be legal?

If none, what other software do you suggest to me that can be run on a single PC?

Thanks.
 
kderakhshani said:
Under what conditions (if any) will this be legal?

Your word use here is slightly confusing. 'Legal' usually means that something isn't against the law or rules. Are you asking under what conditions this software would be appropriate to use and give good results?
 
@Drakkith
Thank you for your comment.
In a wider prospect "legal" means "concordance with the rules of the game". In scientific workss it stands for "not violating the discipline, some scientific law, etc.". For example, if something violates the LAW of conservation of linear momentum, it will be "ILLEGAL".

Anyway, you got it. Do you have any answer to my question?
Thanks
 
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