arXiv subjects

H. G. Khachatryan

Publications and source records attributed to H. G. Khachatryan.

23 records · Page 2Linked to original sources

arXiv2009

Plane-mirroring anomaly in the cosmic microwave background maps

The plane-mirror symmetry previously noticed in the Cosmic Microwave Background (CMB) temperature anisotropy maps of Wilkinson Microwave Anisotropy Probe is shown to possess certain anomalous properties. The degree of the randomness determined by the Kolmogorov stochasticity parameter in the both symmetry regions appears to have identical values which, however, essentially differ from the corresponding values for other sky regions. If the mirroring were of cosmological origin, this would imply either additional randomizing properties in those directions of the Universe or their different line-of-sight depth. This analysis also provides a way to test the hypothesis of a link between the nature of dark energy and inhomogeneities.

astro-ph.CO↗

arXiv2009

Kolmogorov cosmic microwave background sky

A new map of the sky representing the degree of randomness in the cosmic microwave background (CMB) temperature has been obtained. The map based on estimation of the Kolmogorov stochasticity parameter clearly distinguishes the contribution of the Galactic disk from the CMB and reveals regions of various degrees of randomness that can reflect the properties of inhomogeneities in the Universe. For example, among the high randomness regions is the southern non-Gaussian anomaly, the Cold Spot, with a stratification expected for the voids. Existence of its counterpart, a Northern Cold Spot with almost identical randomness properties among other low-temperature regions is revealed. By its informative power, Kolmogorov's map can be complementary to the CMB temperature and polarization sky maps.

astro-ph↗

arXiv2008

Hubble Diagram of Gamma-Rays Bursts calibrated with Gurzadyan-Xue Cosmology

Gamma-ray bursts (GRBs) being the most luminous among known cosmic objects carry an essential potential for cosmological studies if properly used as standard candles. In this paper we test with GRBs the cosmological predictions of the Gurzadyan-Xue (GX) model of dark energy, a novel theory that predicts, without any free parameters, the current vacuum fluctuation energy density close to the value inferred from the SNIa observations. We also compare the GX results with those predicted by the concordance scenario $Λ$-CDM. According to the statistical approach by Schaefer (2007), the use of several empirical relations obtained from GRBs observables, after a consistent calibration for a specific model, enables one to probe current cosmological models. Based on this recently introduced method, we use the 69 GRBs sample collected by Schaefer (2007); and the most recently released SWIFT satellite data (Sakamoto et al. 2007) together with the 41 GRBs sample collected by Rizzuto et al. (2007), which has the more firmly determined redshifts. Both data samples span a distance scale up to redshift about 7. We show that the GX models are compatible with the Hubble diagram of the Schaefer (2007) 69 GRBs sample. Such adjustment is almost identical to the one for the concordance $Λ$-CDM.

astro-ph↗

arXiv2007

Luminosity distance in GX cosmological models

We derive luminosity distance equation in Gurzadyan-Xue cosmological models and compared it with available supernovae and radio galaxies data sets. We found that the luminosity distance does not depend explicitly the speed of light and the gravitation constant, and depends only on the matter parameter (GX-invariant) and curvature.

astro-ph↗

arXiv2007

Invariants and solutions of Gurzadyan-Xue dark energy cosmological models

We have derived the invariants of cosmological models with Gurzadyan-Xue dark energy, along with the solutions for any time dependent light speed and gravitational constant. The correspondence of the invariants with the separatrices found earlier for the GX-models in \cite{Ver06a} is shown, and hence the basis of then detected hidden symmetry is now revealed. Solutions are derived both for radiation and matter models, as well as with both components. It is interesting that, the solutions for the scale factor do not depend on the gravitational constant but only on the 'time evolution' of the speed of light. GX-invariants act as efficient tools describing the models and the phases of the cosmological expansion.

astro-ph↗