78 citations · 333 across the 15 of their papers we have counts for
15 papers
Shallow relic gravitational wave spectrum with acoustic peak
Ramkishor Sharma, Jani Dahl, Axel Brandenburg +1
We study the gravitational wave (GW) spectrum produced by acoustic waves in the early universe, such as would be produced by a first order phase transition, focusing on the low-fre…
Inverse cascading for initial MHD turbulence spectra between Saffman and Batchelor
Axel Brandenburg, Ramkishor Sharma, Tanmay Vachaspati
In decaying magnetohydrodynamic (MHD) turbulence with a strong magnetic field, the spectral magnetic energy density is known to increase with time at small wavenumbers , provide…
Magnetohydrodynamics predicts heavy-tailed distributions of axion-photon conversion
Pierluca Carenza, Ramkishor Sharma, M. C. David Marsh +2
The interconversion of axionlike particles (ALPs) and photons in magnetised astrophysical environments provides a promising route to search for ALPs. The strongest limits to date o…
Batchelor, Saffman, and Kazantsev spectra in galactic small-scale dynamos
Axel Brandenburg, Hongzhe Zhou, Ramkishor Sharma
The magnetic fields in galaxy clusters and probably also in the interstellar medium are believed to be generated by a small-scale dynamo. Theoretically, during its kinematic stage,…
Scaling of the Hosking integral in decaying magnetically-dominated turbulence
Hongzhe Zhou, Ramkishor Sharma, Axel Brandenburg
The Saffman helicity invariant of Hosking and Schekochihin (2021, PRX 11, 041005), which we here call the Hosking integral, has emerged as an important quantity that may govern the…
Low frequency tail of gravitational wave spectra from hydromagnetic turbulence
Ramkishor Sharma, Axel Brandenburg
Hydrodynamic and magnetohydrodynamic turbulence in the early Universe can drive gravitational waves (GWs) and imprint their spectrum onto that of GWs, which might still be observab…
Simulations of helical inflationary magnetogenesis and gravitational waves
Axel Brandenburg, Yutong He, Ramkishor Sharma
Using numerical simulations of helical inflationary magnetogenesis in a low reheating temperature scenario, we show that the magnetic energy spectrum is strongly peaked at a partic…
Simulating relic gravitational waves from inflationary magnetogenesis
Axel Brandenburg, Ramkishor Sharma
We present three-dimensional direct numerical simulations of the production of magnetic fields and gravitational waves (GWs) in the early Universe during a low energy scale matter-…
Constraining models of Inflationary Magnetogenesis with NANOGrav
Ramkishor Sharma
Generation of magnetic field during inflation can explain its presence over a wide range of scales in the Universe. In Ref.\cite{sharma2017}, we proposed a model to generate these…
Imprints of the post recombination dissipation of helical magnetic field on the Cosmic Microwave Background Radiation
Sandhya Jagannathan, Ramkishor Sharma, T. R. Seshadri
Astrophysical magnetic fields decay primarily via two processes namely, ambipolar diffusion and turbulence. Constraints on the strength and the spectral index of non-helical magnet…
Gravitational wave generation in a viable scenario of inflationary magnetogenesis
Ramkishor Sharma, Kandaswamy Subramanian, T. R. Seshadri
Generation of magnetic fields during inflation is a promising mechanism for the origin of the observed large scale magnetic fields in the universe. Among several attempts, a popula…
Scalar spectral index in the presence of Primordial Black Holes
Gaveshna Gupta, Ramkishor Sharma, T. R. Seshadri
We study the possibility of reheating the universe in its early stages through the evaporation of Primordial Black Holes (PBHs) that are formed due to the collapse of the inhomogen…
The generation of helical magnetic field in a viable scenario of Inflationary Magnetogenesis
Ramkishor Sharma, Kandaswamy Subramanian, T. R. Seshadri
We study the generation of helical magnetic fields in a model of inflationary magnetogenesis which is free from the strong coupling and back-reaction problems. To generate helical…
Challenges in Inflationary Magnetogenesis: Constraints from Strong Coupling, Backreaction and the Schwinger Effect
Ramkishor Sharma, Sandhya Jagannathan, T. R. Seshadri +1
Models of inflationary magnetogenesis with a coupling to the electromagnetic action of the form , are known to suffer from several problems. These include the str…
Multifaceted Schwinger effect in de Sitter space
Ramkishor Sharma, Suprit Singh
We investigate particle production à la Schwinger mechanism in an expanding, flat de Sitter patch as is relevant for the inflationary epoch of our universe. Defining states and par…