Public Data Access Overview / Discussion Forum

Hi,

I have this little question. How did you find the stellar mass on SubHalo Catalog? Did you use an aperture radius (like R200 or something) and sum all the particles bound inside or sum all the particles bound to the halo (independient of the radius)? If you have a paper where I can find that details I'll apreciate a lot if you send to me.

Thanks!

Daniel.

There are several different masses available, and they have different definitions, exactly as you mention.

• SubhaloMassInHalfRadType is within the stellar half mass radius.
• SubhaloMassInMaxRadType is within the Vmax radius.
• SubhaloMassInRadType is within twice the stellar half mass radius.
• SubhaloMassType is all mass bound to the subhalo.
• We also now commonly use all stellar mass within a 3D aperture of 30 pkpc. This isn't in the catalog, but is easy to compute.
• We also commonly use gas and stellar masses within R500 or R200, e.g. to compute halo-scale gas and baryon fractions. These also aren't in the catalogs, but can be computed.

Thanks Dylan!

Also I have another question about the same, but respect to the stellar mass in FoF Halo catalog. How define it?

The stellar mass of a FoF halo in the catalog is available as "GroupMassType[4]".

Sorry, but I'm asking how did you calculate the stellar mass (in "GroupMassType") in the FoF Halo Catalog, not in the Subhalo Catalog?

This is "Sum of the individual masses of every particle/cell, split into the six different types, in this group." so it is just the sum of all stars which belong to the FoF halo.

Ok Dylan. Thank you so much!

Hi Dylan, would you please point out where can I find the 3D aperture? I am not sure how to compute the stellar mass within a certain distance.

What 3D aperture do you mean?

For a given distance, computing the mass within that distance means: calculate the distance of all particles/cells from the center, and then select those within the distance.