Although the dark matter is usually assumed to be made up of some form of elementary
particle, primordial black holes (PBHs) could also provide some of it. However, various …

Singularities in any physical theory are either remarkable indicators of the unknown
underlying fundamental theory, or indicate a change in the description of the physical reality …

We review the landscape of QCD axion models. Theoretical constructions that extend the
window for the axion mass and couplings beyond conventional regions are highlighted and …

The advent of the second data release of the Gaia mission, in combination with data from
large spectroscopic surveys, is revolutionizing our understanding of the Galaxy. Thanks to …

We systematically review some standard issues and also the latest developments of
modified gravity in cosmology, emphasizing on inflation, bouncing cosmology and late-time …

This article reviews current understanding of primordial black holes (PBHs), with particular
focus on those massive examples ($\gtrsim $$10^{15}~{\rm g} $) which remain at the …

Axions and other very light axion-like particles appear in many extensions of the Standard
Model, and are leading candidates to compose part or all of the missing matter of the …

Whether or not the primordial gravitational wave (GW) produced during inflation is
sufficiently strong to be observable, GWs are necessarily produced from the primordial …

Gravitational waves (GWs) have a great potential to probe cosmology. We review early
universe sources that can lead to cosmological backgrounds of GWs. We begin by …

The possibility that the dark matter comprises primordial black holes (PBHs) is considered,
with particular emphasis on the currently allowed mass windows at 1 0 16–1 0 17 g, 1 0 20 …