Galaxies, Volume 5, Issue 1

We report the results of an observational program to investigate the gamma-ray and optical variability properties of the vRL NLSY1 galaxies listed in the Yuan et al. sample. We have identified 17 members of the Yuan et al. sample possibly associated...

This article briefly introduces Gaussian processes as a new approach for modelling time series in the field of blazar physics. In the second part of the paper, recent results from an application of GP modelling to the multi-wavelength light curves of...

The ΛCDM model, or concordance cosmology, as it is often called, is a paradigm at its maturity. It is clearly able to describe the universe at large scale, even if some issues remain open, such as the cosmological constant problem, the small-scale pr...

Blazars like Markarian 421 or Markarian 501 are active galactic nuclei (AGN), with their jets orientated towards the observer. They are among the brightest objects in the very high energy (VHE) gamma ray regime (>100 GeV). Their emitted gamma-ray...

The Shapley Concentration (SC) is a galaxy supercluster (few tens of degrees) in the Local Universe (<z>∼0.048) which is currently undergoing cluster mergers and group accretion. It is a diversified environment, with cluster complexes in advanc...

We study the structure and evolution of the hyperaccreting disks and outflows in the gamma ray bursts central engines. The torus around a stellar mass black hole is composed of free nucleons, Helium, electron-positron pairs, and is cooled by neutrino...

Blazars show rapid and high amplitude variability. It is interesting to question what kind of process the variability corresponds to. Maybe it is a result of the instability of the accretion flows. In this work, Fermi daily light curves of 130 source...

We present preliminary data from high-cadence 15-GHz VLBA images of OJ 287 from 1995 to 2015. The ridgelines suggest that the jet is rotating, perhaps with a period of∼30 years. The EVPA of the core rotated by 240° in 2001–2002 and decreased slowly a...

One of the remarkable features of blazars is violent variability over a wide wavelength range. The variation mechanism causing the observed complex behavior is still under debate. The variability timescales range from less than a day to decades. Vari...

We derive the thermodynamic products, in particular the area (or entropy) products of ${\mathcal{H}}^{\pm }$ for a wide variety of black holes (BHs) in anti-de Sitter (AdS) space. We show by explicit and exact calculations that, for this class of BHs, more co...

This paper reviews observational evidence obtained to date about the overall structure of the magnetic fields in the jets of Active Galactic Nuclei (AGN). Because they are sensitive to the line-of-sight magnetic-field component, Faraday rotation observ...

Simultaneous or near-simultaneous observations at multiple frequency bands have the potential to overcome the fundamental limitation imposed by the atmospheric propagation in mm-VLBI observations. The propagation effects place a severe limit in the s...

The Hubble Space Telescope recently celebrated 25 years of operation. Some of the first images of extragalactic optical jets were taken by HST in the mid-1990s; with time baselines on the order of 20 years and state-of-the-art astrometry techniques,...

1H 0323+342 was one of the first vRLNLSy1 galaxies detected at gamma-rays with the Fermi-LAT and is one of the brightest of this class observed at optical wavelengths. We report the results of monitoring the optical flux, polarization and the gamma-r...

GRB 130427A was the most luminous gamma-ray burst detected in the last 30 years. With an isotropic energy output of $8.5\times {10}^{53}$ erg and redshift of 0.34, it combined very high energetics with a relative proximity to Earth in an unprecedente...

In these proceedings, we summarise the exploration so far of the relationship between the afterglow luminosity (measured at rest frame 200s; $\log {\mathrm{L}}_{200\mathrm{s}}$ ) and average afterglow decay rate (measured from rest frame 200s onwards, ${\alpha }_{\&g}$...

The editors of Galaxies would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...]

This work is devoted to multi-frequency studying of the blazar 3C 454.3. The study includes spectroscopic and photometric observations in the optical, IR, and gamma-ray bands. We investigate whether a correlation exists in the light curves at differe...

We present a spectral variability study of a sample of about 25 bright blazars, based on optical spectroscopy. Observations cover the period from the end of 2008 to mid 2015, with an approximately monthly cadence. Emission lines have been identified...

Due to its proximity, M87 is a prime target for next-generation high-resolution VLBI at short millimeter wavelengths, by which the jet launching region and the black hole shadow are expected to be resolved and imaged sometime soon. Along with this si...