Possibility of dark-sector modifications.

[ClaudioNahmad]

Hello,

Firstly i would like to thank everyone who is or has been maintaining the code and making our lives easier. I'm new to FastPM and just a couple weeks ago finally managed to succesfully install and run the program.

My question is in regards with the capabilities of the code to implement so-called "dark sector" alternative models. For example, i've seen on the cosmology module (libfastpm/cosmology.c) that the CPL parameterization (w0waCDM) has been implemented. Is there any possibility of implementing an arbitrary (analytical or numerical) equation of state for the dark energy density?

My other question might show my own ignorance with respect to the FastPM scheme, but here we go: Is there any way to implement a warm dark matter model on FastPM? i know the fastpm scheme relies on a collisionless assumption of matter, to then use other algorithms (e.g. FOF and HOD) to paint the matter distribution. So i'm a bit confused. From this point of view, it seems that warm or hot dark matter is impossible to simulate using the code, but also i'm hoping my lack of knowledge proves me otherwise.

If any of the two were possible to achieve, what would be the best way to approach such implementation?

Thanks in advance for reading and answering the questions! Greetings,

-Claudio Nahmad