New mass bound on fermionic dark matter from a combined analysis of classical dSphs

Dwarf spheroidal galaxies (dSphs) are the most compact dark-matter-dominated objects observed so far. The Pauli exclusion principle limits the number of fermionic dark matter particles that can compose a dSph halo. This results in a well-known lower bound on their particle mass. So far, such bounds were obtained from the analysis of individual dSphs. In this paper, we model dark matter halo density profiles via the semi-analytical approach and analyse the data from eight classical' dSphs assuming the same mass of dark matter fermion in each object. First, we find out that modelling of Carina dSph results in a much worse fitting quality compared to the other seven objects. From the combined analysis of the kinematic data of the remaining seven classical' dSphs, we obtain a new 2 sigma lower bound of m greater than or similar to 190eV on the dark matter fermion mass. In addition, by combining a sub-sample of four dSphs - Draco, Fornax, LeoI, and Sculptor - we conclude that 220eV fermionic dark matter appears to be preferred over the standard cold dark matter at about the 2 sigma level. However, this result becomes insignificant if all seven objects are included in the analysis. Future improvement of the obtained bound requires more detailed data, both from classical' and ultra-faint dSphs.