I am wondering how do we usually estimate the virial mass of a galaxy from our simulation. I am trying to compare data from the observation which provides the virial mass of each galaxy. Do we usually use the stellar mass from "SubhaloMassInRadType" category to estimate the virial mass? I am not sure what is the right way in illustrisTNG so far if we want to know the virial mass of a galaxy.

Thank you!

Dylan Nelson

13 Jan '20

Hi David,

I think this boils down to what is the definition of "virial mass". Whatever it is, then you can measure it in the simulation.

For instance, for central (isolated) dark matter halos, we often refer to a "halo virial mass" defined as R200_Crit. These values are available in the catalogs.

If you want a different definition, it may be available already, or it may need to be measured from the simulation particle data.

I am wondering how do we usually estimate the virial mass of a galaxy from our simulation. I am trying to compare data from the observation which provides the virial mass of each galaxy. Do we usually use the stellar mass from "SubhaloMassInRadType" category to estimate the virial mass? I am not sure what is the right way in illustrisTNG so far if we want to know the virial mass of a galaxy.

Hi David Wang,
I am also facing a similar problem to the one you asked above. Can you share with me how you solved this problem? Should we calculate virial mass using "SubhaloMassInRadRype" and/or "SubhaloMass"?

Hi, Illustris team,

I am wondering how do we usually estimate the virial mass of a galaxy from our simulation. I am trying to compare data from the observation which provides the virial mass of each galaxy. Do we usually use the stellar mass from "SubhaloMassInRadType" category to estimate the virial mass? I am not sure what is the right way in illustrisTNG so far if we want to know the virial mass of a galaxy.

Thank you!

Hi David,

I think this boils down to what is the definition of "virial mass". Whatever it is, then you can measure it in the simulation.

For instance, for central (isolated) dark matter halos, we often refer to a "halo virial mass" defined as

`R200_Crit`

. These values are available in the catalogs.If you want a different definition, it may be available already, or it may need to be measured from the simulation particle data.

Hi David Wang,

I am also facing a similar problem to the one you asked above. Can you share with me how you solved this problem? Should we calculate virial mass using "SubhaloMassInRadRype" and/or "SubhaloMass"?

Thank you