Related papers: Very high energy gamma-rays and the Hubble paramet…
It is possible to explain the discrepancy (tension) between the local measurement of the cosmological parameter $H_0$ (the Hubble constant) and its value derived from the Planck-mission measurements of the Cosmic Microwave Background (CMB)…
Ground based extensive air showers arrays can observe GRBs in the 1-1000 GeV energy range using the "single particle" techique. The sensitivity to detect a GRB as a function of the burst parameters and the detector characteristics are…
The following review presents an attempt to discuss various issues of current interest in Observational Cosmology, the selection of which as well as the emphasis given, reflects my own preference and biases. After presenting some…
A linearity test shows H_0 to decrease by 7% out to 18000 km/s. The value at 10000 km/s is a good approximation to the mean value of Ho over very large scales. The construction of the extragalactic distance scale is discussed. Field…
Extraterrestrial gamma-ray astronomy is now a source of new knowledge in the fields of astrophysics, cosmic-ray physics, and the nature of dark matter. The next absolutely necessary step in the development of extraterrestrial high-energy…
Two of the most pressing challenges in cosmology are the persistent discrepancy in measurements of the Hubble constant, referred to as the Hubble tension, and the deficit of baryons in the local Universe, known as the missing baryon…
Relations connecting gamma ray burst quantities can be used to constrain cosmographic parameters of the Hubble law at medium-high redshifts. We consider a sample of 27 gamma ray bursts to construct the luminosity distance to redshift…
We constrain the Hubble constant H$_0$ using Fast Radio Burst (FRB) observations from the Australian Square Kilometre Array Pathfinder (ASKAP) and Murriyang (Parkes) radio telescopes. We use the redshift-dispersion measure (`Macquart')…
Gamma-ray bursts (GRBs) are one of the candidates of ultra-high-energy (around 10^18.5 eV) cosmic-ray (UHECR) sources. We investigate high-energy cosmic-ray acceleration including heavy nuclei in GRBs by using Geant 4, and discuss its…
Very high energy gamma-ray data obtained by CAT and HEGRA from active galactic nucleus Mkn 501 are used to constrain the cosmic Mid-Infrared background. While the entire infrared and submillimeter spectrum shape based on models has been…
We study how the determination of the Hubble constant from cosmological distance measures is affected by models of dark energy and vice versa. For this purpose, constraints on the Hubble constant and dark energy are investigated using the…
We derive new constraints on the Hubble parameter $H_0$ using the available data on $H(z)$ from cosmic chronometers (CCH), and the Hubble rate data points from the supernovae of Type Ia (SnIa) of the Pantheon compilation and the Hubble…
We present results from the High Energy Stereoscopic System (H.E.S.S.) follow-up observations of Gamma-ray Bursts (GRBs) between 2004 and 2019. We are focusing on non-detections and providing the most extensive set of very-high-energy (VHE,…
Gamma-ray bursts (GRBs) are attractive objects for constraining the nature of dark energy in a way complementary to other cosmological probes, especially at high redshifts. However, the apparent magnitude of distant GRBs can be distorted by…
Gravitational waves observation with electromagnetic counterparts provides an approach to measure the Hubble constant which is also known as the bright siren method. Great hope has been put into this method to arbitrate the Hubble tension.…
The arguments suggesting an association between the sources of cosmological gamma-ray bursts (GRBs) and the sources of ultra-high energy cosmic rays (UHECRs) are presented. Recent GRB and UHECR observations are shown to strengthen these…
The recent observations of gravitational-wave and electromagnetic emission produced by the merger of the binary neutron-star system GW170817 have opened the possibility of using standard sirens to constrain the value of the Hubble constant.…
Recently funded satellites will map the cosmic microwave background radiation with unprecedented sensitivities and angular resolutions. Assuming only primordial adiabatic scalar and tensor perturbations, we evaluate how accurately…
We suggest that the solution to the cosmological vacuum energy puzzle does not require any new field beyond the standard model, but rather can be explained as a result of the interaction of the infrared sector of the effective theory of…
Gravitational lensing is now widely and successfully used to study a range of astronomical phenomena, from individual objects, like galaxies and clusters, to the mass distribution on various scales, to the overall geometry of the Universe.…