Clusters of galaxies : observational properties of the diffuse radio emission

Clusters of galaxies, as the largest virialized systems in the Universe, are ideal laboratories to study the formation and evolution of cosmic structures...(abridged)... Most of the detailed knowledge of galaxy clusters has been obtained in recent years from the study of ICM through X-ray Astronomy. At the same time, radio observations have proved that the ICM is mixed with non-thermal components, i.e. highly relativistic particles and large-scale magnetic fields, detected through their synchrotron emission. The knowledge of the properties of these non-thermal ICM components has increased significantly, owing to sensitive radio images and to the development of theoretical models. Diffuse synchrotron radio emission in the central and peripheral cluster regions has been found in many clusters. Moreover large-scale magnetic fields appear to be present in all galaxy clusters, as derived from Rotation Measure (RM) studies. Non-thermal components are linked to the cluster X-ray properties, and to the cluster evolutionary stage, and are crucial for a comprehensive physical description of the intracluster medium. They play an important role in the cluster formation and evolution. We review here the observational properties of diffuse non-thermal sources detected in galaxy clusters: halos, relics and mini-halos. We discuss their classification and properties. We report published results up to date and obtain and discuss statistical properties. We present the properties of large-scale magnetic fields in clusters and in even larger structures: filaments connecting galaxy clusters. We summarize the current models of the origin of these cluster components, and outline the improvements that are expected in this area from future developments thanks to the new generation of radio telescopes.Comment: Accepted for the publication in The Astronomy and Astrophysics Review. 58 pages, 26 figure

Extragalactic Radio Continuum Surveys and the Transformation of Radio Astronomy

Next-generation radio surveys are about to transform radio astronomy by discovering and studying tens of millions of previously unknown radio sources. These surveys will provide new insights to understand the evolution of galaxies, measuring the evolution of the cosmic star formation rate, and rivalling traditional techniques in the measurement of fundamental cosmological parameters. By observing a new volume of observational parameter space, they are also likely to discover unexpected new phenomena. This review traces the evolution of extragalactic radio continuum surveys from the earliest days of radio astronomy to the present, and identifies the challenges that must be overcome to achieve this transformational change.Comment: To be published in Nature Astronomy 18 Sept 201

Morphology of testicular parenchyma adjacent to germ cell tumours. An interim report

A comparative morphological analysis of parenchyma adjacent to testicular germ cell tumours (TGCT) was performed in a series of 181 orchidectomy specimens: 86 with seminomas (Se), 72 with nonseminomatous germ cell tumours (NS) and 23 with combined tumours (CT, which have a Se and a NS component). The following morphological features were semiquantitatively scored: spermatogenesis (modified Johnsen score); amount of tubular atrophy; amount of carcinoma in situ (CIS); amount of intertubular tissue. Absence and presence was scored for the following features: lymphocytic infiltrate surrounding and invading CIS; intratubular seminoma (ISe); intratubular nonseminoma (INS); microlithiasis; diffuse and nodular hyperplasia of Leydig cells; angioinvasiveness; testicular angiopathy. Using non-parametric statistics these features were correlated with each other and with tumour type, tumour size and age of the patient. Se-patients presented at significantly higher age than NS-patients (36 vs 29 years, p=0.001). The age of patients with CT (32 years) was in between that of Se- and NS-patients. No correlation was found between patient age and tumour size. Parenchyma adjacent to Se, compared to parenchyma adjacent to NS had the following significant differences: a lower Johnsen score (5.6 vs 7.2, p=0.005); less frequent (85% vs 97% of specimens, p=0.016) and a lesser amount of CIS (26% vs 32% of tubules, p=0.015); more frequent peri- (80% vs 60% of specimens, p=0.001) and intratubular (68% vs 30% of specimens, p=0.001) lymphocytic infiltrates; more extensive tubular atrophy (36% vs 15% of tubules, p=0.001); and a larger area of intertubular tissue (42% vs 34% of parenchyma area, p=0.016). The pooled Se and CT had a significantly higher frequency of ISe than the NS (31% vs 17% of specimens, p=0.036). With one exception INS was only found adjacent to NS or CT, with a frequency of 16%, and 20% of the specimens, respectively. It was significantly associated with angio-invasiveness. In specimens lacking angio-invasion the frequency of INS was 6%. The correlation of INS with tumour size and patient age was studied in a series of 145 NS and CT (95 from the original series supplemented by 50 newer cases). In this series INS was significantly associated with smaller tumours and younger patients. Extensive tubular atrophy was significantly correlated with higher age, the diagnosis of Se, a low Johnsen score, and the presence of angiopathy. The more tubular atrophy, the less CIS (both in incidence and amount). Inversely, a higher Johnsen score is associated with smaller tumours, the diagnosis of NS or CT, a higher incidence and a larger amount of CIS, and little tubular atrophy. Tubules with mature spermatogenesis were found in 42% of the specimens regardless of tumour type. We conclude that ISe and INS are probably frequent intermediate stages between CIS and Se and NS, respectively. The features of parenchyma adjacent to Se are probably due to the host response elicited by the invasive Se, which secondarily also affects CIS. The long time to clinical presentation allows the host to eradicate most of the CIS by the time the tumour is surgically removed. The much less extensive morphological features of a host response in parenchyma adjacent to NS support the contention that NS originates as INS, behind the blood/testis barrier, without exposure of the host to tumour cells with a seminomatous phenotype (CIS- or Se cells). Microlithiasis and testicular angiopathy are frequent, but not specific findings in parenchyma next to TGCT. Their relationship with the development with TGCT is unexplained