Toward a General Parameterization of the Warm Dark Matter Halo Mass Function

• Published in: The Astrophysical journal Vol. 897; no. 2; pp. 147 - 152
• Main Author: Lovell, Mark R.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.07.2020; IOP Publishing
• Subjects: Anomalies; Astronomical models; Astrophysics; Cold dark matter; Computer simulation; Constraint modelling; Dark matter; Halos; Local group (astronomy); Neutrinos; Parameterization; Relative abundance; Warm dark matter
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ab982a

Studies of flux anomalies statistics and perturbations in stellar streams have the potential to constrain models of warm dark matter (WDM), including sterile neutrinos. Producing these constraints requires a parameterization of the WDM mass function relative to that of the cold dark matter (CDM) equivalent. We use five WDM models with half-mode masses, Mhm = [1.3,35] × 108 , spread across simulations of the Local Group, lensing ellipticals and the z = 2 universe, to generate such a parameterization: we fit parameters to a functional form for the WDM-to-CDM halo mass function ratio, , of . For MX virial mass of central halos we obtain = 2.3, β = 0.8, and γ = −1.0, and this fit is steeper than the extended Press-Schechter formalism predicts. For MX mass of subhalos we instead obtain = 4.2, β = 2.5, and γ = −0.2; in both mass definitions the scatter is ∼20%. The second fit typically underestimates the relative abundance of z = 2 WDM subhalos at the tens of percent level. We caution that robust constraints will require bespoke simulations and a careful definition of halo mass, particularly for subhalos of mass <108 .