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We study the formation of primordial black holes (PBHs) in the early Universe during a period of slow reheating after inflation. We demonstrate how the PBH formation mechanism may change even before the end of the matter-dominated phase and…
Large-amplitude density perturbations may have collapsed during the radiation dominated epoch of the Universe to form primordial black holes (PBHs). There are several constraints to the abundance of PBHs that stem from evaporation or…
In a class of single field models of inflation, the idea of Primordial Black holes(PBHs) production is studied. In this case, the dynamics on small cosmological scales differs significantly from that of the large scales probed by the…
If primordial black holes (PBHs) formed at the quark-hadron epoch, their mass must be close to the Chandrasekhar limit, this also being the characteristic mass of stars. If they provide the dark matter (DM), the collapse fraction must be of…
Cosmological $\alpha$-attractors stand out as particularly compelling models to describe inflation in the very early universe, naturally meeting tight observational bounds from cosmic microwave background (CMB) experiments. We investigate…
It has been argued that the small perturbations to the homogeneous and isotropic configurations of a canonical scalar field in an expanding universe do not grow. We show that this is not true in general, and clarify the root of the…
Primordial black holes (PBHs) can form in the early Universe, for instance during radiation domination, from the collapse of large-amplitude density perturbations shortly after horizon re-entry. This mechanism establishes an approximate…
Primordial black hole (PBH) abundance limits constrain the primordial power spectrum, and hence models of inflation, on scales far smaller than those probed by cosmological observations. Single field inflation models which are compatible…
Primordial Black Holes (PBHs) might have formed in the early Universe as a consequence of the collapse of density fluctuations with an amplitude above a critical value $\delta_{c}$: the formation threshold. Although for a…
We study Primordial Black Holes (PBHs) formed by the collapse of rare primordial fluctuations during an early period of Matter Domination. The collapse threshold strongly depends on the shape of the peaks, decreasing as they become flatter…
We propose and study the new (generalized) E-type $\alpha$-attractor models of inflation, in order to include formation of primordial black holes (PBHs). The inflaton potential has a near-inflection point where slow-roll conditions are…
The formation of primordial black holes in the early universe in the Brans-Dicke scalar-tensor theory of gravity is investigated. Corrections to the threshold value of density perturbations are found. Above the threshold, the gravitational…
We discuss the possibility that dark matter corresponds to an oscillating scalar field coupled to the Higgs boson. We argue that the initial field amplitude should generically be of the order of the Hubble parameter during inflation, as a…
We study the generation of primordial black holes (PBH) in a single field inflection point model of inflation wherein the effective potential is expanded up to the sextic order and the inversion symmetry is imposed such that only even…
We show that supersymmetry and inflation, in a broad class of models, generically lead to formation of primordial black holes (PBHs) that can account for dark matter. Supersymmetry predicts a number of scalar fields that develop a coherent…
We study the formation of structure in the Universe assuming that dark matter can be described by a scalar field $\tilde{\Phi}$ with a potential $V(\Phi)=-\mathfrak{m}^{2}\tilde{\Phi}^{2}/2+\lambda\tilde{\Phi}^4/4$. We derive the evolution…
We consider the formation of primordial black holes (PBHs), during the radiation-dominated Universe, generated from the collapse of super-horizon curvature fluctuations that are overlapped with others on larger scales. Using a set of…
In this paper the thermal evolution of scalar field dark matter particles at finite cosmological temperatures is studied. Starting with a real scalar field in a thermal bath and using the one loop quantum corrections potential, we rewrite…
Primordial Black Holes (PBHs) can form in the radiation dominated early Universe from the collapse of large density perturbations produced by inflation. A power-law parameterisation of the primordial power spectrum is often used to…
Primordial black holes (PBHs) can form in the early Universe via the collapse of large density perturbations. There are tight constraints on the abundance of PBHs formed due to their gravitational effects and the consequences of their…