How to confirm one line of sight ?

Yan Shulan
  • 4 Apr

If we want to get the message in one line of sight , such as the velocity of LOS or the distance of LOS , how can we do to confirm one line of sight and get useful data ?

Dylan Nelson
  • 5 Apr

Hello,

I'm afraid I don't understand exactly what you are trying to do, can you explain more?

If you want to determine a physical property of gas, stars, or dark matter along a particular sight-line in a simulation snapshot, you can load the particle data, and then search for particles which are near to (or intersect) the sightline.

Yan Shulan
  • 5 Apr

Thanks, Dylan.
Actually, I want to get some physical properties along a particular sight-line. But before loading the particle data, I need load the subhalos data first. And I don't know how many particles in the subhalo intersect the sightline. Or briefly, how can I get the full particle data which may be in different subhalos in one direction. What's more, I also want to know how to calculate the velocity of line of sight. In your API data access, using {vis_query} can get the png image of vel_los, if I need the data of vel_los, how can I get it ?

Dylan Nelson
  • 5 Apr

Hello,

(1) There isn't any fast or easy way to know which particles, or which subhalos, intersect a sightline. You must load their Coordinates (or e.g. SubhaloPos) and check.

(2) The most simple approach is to take a LOS which is along one of the x,y,z axes of the simulation box. So if the LOS direction is z, then the LOS velocity is exactly the Velocities[2] field. If the LOS direction is x, then it is Velocities[0].

Yan Shulan
  • 5 Apr

Thank you very much

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