Encieh Erfani

• PhD
• Researcher at Johannes Gutenberg University Mainz

We study how the bounds on the abundance of Primordial Black Holes (PBHs) and the constraints on power spectrum are modified if a non-standard evolution phase takes place between the end of inflation and the Standard radiation-dominated (RD) universe after inflation. The constraints on PBH abundance and power spectrum are computed using the new, fr...

This is a proposal for our Lindau Sciathon group 2024: https://sciathon.org/projects-2024/

We study how the bounds on the abundance of Primordial Black Holes (PBHs) and the constraints to the power spectrum (PS) are modified if a non-standard evolution phase takes place between the end of inflation and the Standard Big Bang (SBB). The constraints on PBH abundance and PS are computed using the new, freely available, PBHBeta library, which...

Encieh Erfani says that more must be done to support students in Iran who are risking their lives to protest against oppression.

We study the merger history of primordial black holes (PBHs) in a scenario where they represent the dominant dark matter component of a typical dwarf galaxies' core. We investigate the possibility of a sequence of collisions resulting in a hierarchical merger of black holes, and look at the final mass spectrum in such clusters , which initially pre...

We study the merger history of primordial black holes (PBHs) in a scenario where they represent the dominant dark matter component of a typical dwarf galaxies' core. We investigate the possibility of a sequence of collisions resulting in a hierarchical merger of black holes and look at the final mass spectrum in such {\it clusters}, which initially...

We study primordial black holes (PBHs) formation in the excursion set theory (EST) in a vast range of PBHs masses with and without confirmed constraints on their abundance. In this work, we introduce a new concept of the first touch in the context of EST for PBHs formation. This new framework takes into account the earlier horizon reentry of smalle...

With the discovery of gravitational waves from merging pairs of massive black holes, the interest in the question of whether Primordial Black Holes (PBHs) could constitute the Dark Matter (DM) has recently been revived. I will review the different mechanisms for (DM) PBHs formation with a focus on inflation which can source the required large densi...

We study primordial black holes (PBHs) formation in the excursion set theory (EST) in a vast range of PBHs masses with and without confirmed constraints on their abundance. In this work, a new concept of the first touch in the EST is introduced for PBHs formation which takes into account the earlier horizon reentry of smaller masses. Our study show...

We study the possibility that particle production during inflation can source the required power spectrum for dark matter (DM) primordial black holes (PBH) formation. We consider the scalar and the gauge quanta production in inflation models, where in the latter case, we focus in two sectors: inflaton coupled i) directly and ii) gravitationally to...

In this work we study the chromo-natural inflation model in the anisotropic setup. Initiating inflation from Bianchi type-I cosmology, we analyze the system thoroughly during the slow-roll inflation, from both analytical and numerical points of view. We show that the isotropic FRW inflation is an attractor of the system. In other words, anisotropie...

For the first time, the running of the running of the spectral index, $\beta_s$ has been measured by Planck. This parameter is crucial for dark matter Primordial Black Holes (PBHs) formation. We study the PBHs formation in inflation potentials with superimposed periodic oscillations. We show that the value of $\beta_s$ suggested by the recent CMB d...

The study started in a former work about the Dilaton mean field stabilization thanks to the effective potential generated by the existence of massive fermions, is here extended. Three loop corrections are evaluated in addition to the previously calculated two loop terms. The results indicate that the Dilaton vacuum field tend to be fixed at a high...

Axions might play a crucial role for the solution of the strong CP-problem and explanation of cold dark matter in the universe. In addition they may find applications in the formulation of inflationary models for the early universe and can serve as candidates for quintessence. We show that all these phenomena can be described within a single framew...

A broad range of single field models of inflation are analyzed in light of all relevant recent cosmological data, checking whether they can lead to the formation of long--lived Primordial Black Holes (PBHs) as candidate for dark matter. To that end we calculate the spectral index of the power spectrum of primordial perturbations as well as its firs...

The extension of study done in a previous work about the dilaton mean field stabilization thanks to the potential generated by massive fermions, is reviewed. Three loop corrections were evaluated in addition to the previously calculated two loop terms. The results indicate that the dilaton vacuum field tend to be fixed at a high value close to the...

The International School for Advanced Studies (SISSA) was founded in 1978 and was the first institution in Italy to promote post-graduate courses leading to a Doctor Philosophiae (or PhD) degree. A centre of excellence among Italian and international universities, the school has around 65 teachers, 100 post docs and 245 PhD students, and is located...

We revisit the question whether the running-mass inflation model allows the formation of Primordial Black Holes (PBHs) that are sufficiently long-lived to serve as candidates for Dark Matter. We incorporate recent cosmological data, including the WMAP 7-year results. Moreover, we include "the running of the running" of the spectral index of the pow...