Dear yt:

I have one simple question, but it bothers me these days.

I used the yt to analysis the "hdf5" files, which generated by Gadget-2. These files have basic fields, like: ("PartType0", "*"), ("PartType1", "*") and ("all", "*"). Then I want to plot the density map and temperature map, it seems need some derived fields, like: ("gas", "density") and ("gas", "temperature").

I'm curious about how the ("gas","temperature") was derived, so I browsed a lots of documents on the Web, but found nothing. Please see
About the field of ('gas','temperature'),  there is "No source available" in "Field Source"!

In my data, the field ("PartType0","InternalEnergy") is provided by me, and I think the temperature should calculated by Internal Energy "E" with the function: k*T = (Gamma -1)*µ*mp*E, where k = 1.38E-16 erg/K is Boltzmann constant, Gamma = 5/3 for adiabat particles, μ = 0.6 is the corresponding mean molecular weight, and mp = 1.67E-24 g is proton mass. But this result is about half of the value of ("gas","temperature").
So what you may know is why, which one is right? I need your help!

Thank you a lot, and happy new year!


Dan Hu
Department of Physics, Shanghai Jiao Tong University
800 Dongchuan Road, Minhang, Shanghai 200240, PRC
E-mail :