Related papers: Dark matter as Planck relics without too exotic hy…
We show that density spikes begin to form from dark matter particles around primordial black holes immediately after their formation at the radiation-dominated cosmological stage. This follows from the fact that in the thermal velocity…
The origin of dark matter in the universe may be weakly interacting scalar particles produced by amplification of quantum fluctuations during a period of dilaton-driven inflation. We present two interesting cases, the case of small…
Primordial black holes (PBHs) could be formed if large perturbations are generated on small scales in inflation. We study a toy inflation model with a local minimum. The curvature perturbations are enhanced when the inflaton passes through…
Primordial black holes (PBHs) offer a compelling candidate for dark matter. The production of PBHs through well-tested and accepted physical processes is highly worthy of investigation. This work highlights the role of turbulences in the…
Strange Quark Nuggets are the relics of the microsecond old universe after the big bang. The universe having experienced a mini inflation of 7-e folding has gone through supercooling leading to a first order phase transition from quark to…
Hawking evaporation of primordial black holes (PBH) with masses ranging from $\sim 10^{-1}$ to $\sim 10^9$ g can generate the whole observed dark matter (DM) relic density. However, a second DM production mechanism, like freeze-out or…
Historically the most popular dark matter candidates have been new elementary particles, such as Weakly Interacting Massive Particles and axions. However Primordial Black Holes (PBHs), black holes formed from overdensities in the early…
Vilkovisky has claimed to have solved the black hole backreaction problem and finds that black holes lose only ten percent of their mass to Hawking radiation before evaporation ceases. We examine the implications of this scenario for cold…
Dark matter is a fundamental constituent of the universe, which is needed to explain a wide variety of astrophysical and cosmological observations. Although the existence of dark matter was first postulated nearly a century ago and its…
Production of high-energy gravitational objects is a common feature of gravitational theories. The primordial universe is a natural setting for the creation of black holes and other nonperturbative gravitational entities. Cosmic black holes…
We review the formation and evaporation of primordial black holes (PBHs) and their possible contribution to dark matter. Various constraints suggest they could only provide most of it in the mass windows $10^{17}$ - $10^{23}\,$g or $10$ -…
We demonstrate the existence of a generic, efficient and purely gravitational channel producing a significant abundance of dark relics during reheating after the end of inflation. The mechanism is present for any inert scalar with the…
We devise a novel mechanism and for the first time demonstrate that the Higgs model in particle physics can drive the inflation to satisfy the cosmic microwave background observations and simultaneously enhance the curvature perturbations…
Primordial black holes (PBHs) represent a natural candidate for one of the components of the dark matter (DM) in the Universe. In this review, we shall discuss the basics of their formation, abundance and signatures. Some of their…
We study a scenario in which the baryon asymmetry is created through Hawking radiation from primordial black holes via a dynamically-generated chemical potential. This mechanism can also be used to generate the observed dark matter…
Macroscopic dark matter like nontopological solitons can form either via the fusion and accumulation of free particles or during cosmological phase transitions. Both mechanisms can create dark matter with large masses ranging from TeV to…
Black holes below Chandrasekhar mass limit (1.4 $M_{\odot}$) can not be produced via any standard stellar evolution. Recently, gravitational wave experiments have also discovered unusually low mass black holes whose origin is yet to be…
Various mechanisms have been suggested for the formation of Primordial Black Holes (PBHs), and this thesis focuses on the standard mechanism based on the critical collapse of cosmological fluctuations. The underlying idea is that during…
Too light primordial black holes evaporate and are therefore strongly constrained by various bounds, e.g. Cosmic Microwave Background distortion. However, if they are formed strongly clustered, the corresponding haloes may collapse in…
We present a scenario of vector dark matter production during inflation containing a complex inflaton field which is charged under a dark gauge field and which has a symmetry breaking potential. As the inflaton field rolls towards the…