Universality of the halo mass function in modified gravity cosmologies

Understand

We study the halo mass function (HMF) in modified gravity (MG) models using a set of large $N$-body simulations -- the ELEPHANT suite.

• We consider two popular beyond-general relativity scenarios: the Hu-Sawicki chameleon $f(R)$ model and the normal branch of the Dvali-Gabadadze-Porrati braneworld (nDGP).
• We show that in MG, analytic formulation based on the Press-Schechter framework offers a grossly inaccurate description of the HMF.
• We find, however, that once the HMF is expressed in terms of the dimensionless multiplicity function, it approximately assumes a redshift-independent universal character for all the models.