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Kayoomars Karami

Kayoomars Karami

Academic rank: Professor
ORCID:
Education: PhD.
ScopusId: 22979495000
HIndex:
Faculty: Faculty of Science
Address: Department of Physics, University of Kurdistan Pasdaran St., P.O.Box: 66177-15175 Sanandaj - Iran
Phone:

Research

Title
Primordial Black Holes Formation and Secondary Gravitational Waves in Nonminimal Derivative Coupling Inflation
Type
JournalPaper
Keywords
Cosmic inflation, Primordial black holes, Gravitational waves
Year
2021
Journal ASTROPHYSICAL JOURNAL
DOI
Researchers Zeinab Teimoori ، Kazem Rezazadeh Sarab ، Kayoomars Karami

Abstract

We study the possibility of the primordial black holes (PBHs) formation with the aim of finding a considerable fraction of dark matter (DM), using the gravitationally enhanced friction mechanism which arises from a nonminimal derivative coupling between the scalar field and the gravity. Assuming the nonminimal coupling parameter as a special function of the scalar field and considering the potential of natural inflation, we find three parameter sets that produce a period of ultra slow-roll inflation. This leads to sufficiently large enhancement in the curvature power spectra to form PBHs. We show that under the gravitationally enhanced friction mechanism, PBHs with a mass around( ) 10-12 M can constitute around 96% of the total DM and so this class of PBHs can be taken as a great candidate for DM. We further study the secondary gravitational waves (GWs) in our setting and show that our model predicts the peak of the present fractional energy density as ΩGW0 ∼ 10−8 at different frequencies for all the three parameter sets. This value lies well inside the sensitivity region of some GWs detectors at some frequencies, and therefore the observational compatibility of our model can be appraised by the data from these detectors.