Hello fellow astronomers!
I'm studying simulated elliptical galaxies and your Visualize Galaxies and Halos tool appeared very useful. However I cannot understand the meaning of some fields, for example what is the difference between velocity_x and vel_x? Where can I find the detailed explanations for all of the fields?
Dylan Nelson
14 May '21
Dear Ekaterina,
You are right, this is not documented sufficiently. I will think how best to describe these more fully in the future.
You can find a list of all available options on the API specifications, under The known "particle/cell quantities" which can be used for partField are:.
In particular, velocity_x and vel_x are exactly the same, I will remove one for clarity in the future.
Ekaterina Kireeva
14 May '21
Thanks! Looking forward to getting the full describe someday!
Rodrigo Freitas
19 Sep '22
Hi Dylan,
I am downloading visualization of halos through the API and I using the method "sphMap". I assume that this method is an interpolation kernel, right?
Is there any reference for the mathematical form of "sphMap" or the parameters used in it?
Dylan Nelson
19 Sep '22
Yes this is the "standard" cubic spline (smoothing) kernel used in SPH, with one size parameter h which, for gas, is set equal to 2.5 times the equivalent-volume spherical radius, as described in e.g. Nelson+16.
You can find similar methods in public codes such as pysphviewer, pygad, or swiftsimio.
I hope to publicly release all the code behind the TNG website functionality in the future, as a source of reference.
Hello fellow astronomers!
I'm studying simulated elliptical galaxies and your Visualize Galaxies and Halos tool appeared very useful. However I cannot understand the meaning of some fields, for example what is the difference between velocity_x and vel_x? Where can I find the detailed explanations for all of the fields?
Dear Ekaterina,
You are right, this is not documented sufficiently. I will think how best to describe these more fully in the future.
You can find a list of all available options on the API specifications, under
The known "particle/cell quantities" which can be used for partField are:.In particular,
velocity_xandvel_xare exactly the same, I will remove one for clarity in the future.Thanks! Looking forward to getting the full describe someday!
Hi Dylan,
I am downloading visualization of halos through the API and I using the method "sphMap". I assume that this method is an interpolation kernel, right?
Is there any reference for the mathematical form of "sphMap" or the parameters used in it?
Yes this is the "standard" cubic spline (smoothing) kernel used in SPH, with one size parameter
hwhich, for gas, is set equal to 2.5 times the equivalent-volume spherical radius, as described in e.g. Nelson+16.You can find similar methods in public codes such as pysphviewer, pygad, or swiftsimio.
I hope to publicly release all the code behind the TNG website functionality in the future, as a source of reference.
Thank you for the quick response!