Study of large-scale radio structures associated with spiral galaxies

Almost all known powerful extragalactic radio sources, named radio galaxies, are hosted by elliptical (or lenticular) galaxies. However, few examples of strong radio galaxies associated with spiral galaxies have been found in the recent years. In the very centre of a parent galaxy the active galactic nucleus (AGN) can be found. AGN is a small-size, rare formation composed of a supermassive black hole (SMBH; with masses exceeding 10 million Solar masses) surrounded by matter forming an accretion disk, a dusty torus and a corona - heated to millions of degrees and, in some cases, jets of relativistic plasma. These energetic, collimated outflows sometimes blown into huge lobes have their origin near the SMBH and are characterized by a wide range of observed sizes (from dozens of kiloparsecs up to a few megaparsecs). A very important aspect in the study of AGNs is to answer the question why only few powerful, large-scale radio sources are associated with spiral galaxies. Here we present these unique objects with particular interest in radio galaxy B0313$-$192 which is located in Abell 428 galaxy cluster

An innovative silicon photomultiplier digitizing camera for gamma-ray astronomy

The single-mirror small-size telescope (SST-1M) is one of the three proposed designs for the small-size telescopes (SSTs) of the Cherenkov Telescope Array (CTA) project. The SST-1M will be equipped with a 4 m-diameter segmented mirror dish and an innovative fully digital camera based on silicon photo-multipliers (SiPMs). Since the SST sub-array will consist of up to 70 telescopes, the challenge is not only to build a telescope with excellent performance, but also to design it so that its components can be commissioned, assembled and tested by industry. In this paper we review the basic steps that led to the design concepts for the SST-1M camera and the ongoing realization of the first prototype, with focus on the innovative solutions adopted for the photodetector plane and the readout and trigger parts of the camera. In addition, we report on results of laboratory measurements on real scale elements that validate the camera design and show that it is capable of matching the CTA requirements of operating up to high-moon-light background conditions.Comment: 30 pages, 61 figure