Tommi Tenkanen

Primordial black hole constraints for extended mass functions

We revisit the cosmological and astrophysical constraints on the fraction of the dark matter in primordial black holes (PBHs) with an extended mass function. We consider a variety of mass functions, all of which are described by three parameters: a characteristic mass and width and a dark matter fraction. Various observations then impose constraints on the dark matter fraction as a function of the first two parameters. We show how these constraints relate to those for a monochromatic mass function, demonstrating that they usually become more stringent in the extended case than the monochromatic one. Considering only the well-established bounds, and neglecting the ones that depend on additional astrophysical assumptions, we find that there are three mass windows, around

The Dawn of FIMP Dark Matter: A Review of Models and Constraints

4\times 10^{-17}M_\odot,

Isocurvature constraints on portal couplings

2\times 10^{-14}M_\odot

Standard Model with a real singlet scalar and inflation

and

Primordial black holes from inflaton and spectator field perturbations in a matter-dominated era

25-100M_\odot

A Strong Electroweak Phase Transition from the Inflaton Field

, where PBHs can constitute all dark matter. However, if one includes all the bounds, PBHs can only constitute of order

Reheating the Standard Model from a hidden sector

10\%

Resurrecting Quadratic Inflation with a non-minimal coupling to gravity

of the dark matter.

Feebly interacting dark matter particle as the inflaton

We present an overview of scenarios where the observed Dark Matter (DM) abundance consists of Feebly Interacting Massive Particles (FIMPs), produced nonthermally by the so-called freeze-in mechanism. In contrast to the usual freeze-out scenario, frozen-in FIMP DM interacts very weakly with the particles in the visible sector and never attained thermal equilibrium with the baryon–photon fluid in the early Universe. Instead of being determined by its annihilation strength, the DM abundance depends on the decay and annihilation strengths of particles in equilibrium with the baryon–photon fluid, as well as couplings in the DM sector. This makes frozen-in DM very difficult but not impossible to test. In this review, we present the freeze-in mechanism and its variations considered in the literature (dark freeze-out and reannihilation), compare them to the standard DM freeze-out scenario, discuss several aspects of model building, and pay particular attention to observational properties and general testability o...