10 papers
Gravitational Waves from Primordial Black Holes: Connecting Low-Frequency Scalar-Induced Signatures to High-Frequency Binary Mergers
Ashu Kushwaha
Formation of primordial black holes (PBHs) requires a significant enhancement of curvature perturbations. This enhancement generates a twofold gravitational wave (GW) signature: a…
Secondary Production of Photons from ALP Dark Matter interacting with a Cosmological Magnetic Field
Abdias Aires, Robert Brandenberger, Ashu Kushwaha
Under the assumption that dark matter is a coherently oscillating pseudoscalar field coupled to electromagnetism by the usual Chern-Simons term, we study the production of secondar…
Probing Axion-Photon conversion via circular polarization imprints in the CMB -mode observations
Ashu Kushwaha, Rajeev Kumar Jain
In the presence of a background magnetic field, axions or axion-like particles (ALPs) can be resonantly converted to photons when their mass is nearly equal to the effective photon…
Revisiting Constraints on Primordial Curvature Power Spectrum from PBH Abundances
Ashu Kushwaha, Teruaki Suyama
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 hor…
An upper limit on cosmological chiral gravitational wave background
Mohammad Ali Gorji, Ashu Kushwaha, Teruaki Suyama
Within the standard framework in which electroweak sphaleron processes relate lepton and baryon number, we derive an upper limit on the amplitude of a chiral gravitational wave bac…
Excursion Set Approach to Primordial Black Holes: Cloud-in-Cloud and Mass Function Revisited
Ashu Kushwaha, Teruaki Suyama
The abundance and mass function of primordial black holes (PBHs) are often estimated using the Press-Schechter (PS) formalism. In the case of halo formation, the PS formalism suffe…