Understanding the variable emission of blazars observed with gamma-ray telescopes and Fermi has become a major challenge for theoretical models of particle acceleration. Here, we introduce a novel time-dependent emission model in which the maximum energy of particles is determined from a balance between Fermi type I and II acceleration energy gains and radiative energy losses, allowing for an explanation of both the characteristic spectral energy distribution of blazars and their intrinsic sub-hour variability. Additionally, we can determine the physical condition of the emitting plasma concerning its turbulence and typical shock speeds.

This paper provides an overview of the ESA Planck mission and its scientific promises. Planck is equipped with a 1.5–m effective aperture telescope with two actively-cooled instruments observing the sky in nine frequency channels from 30 GHz to 857 GHz: the Low Frequency Instrument (LFI) operating at 20 K with pseudo-correlation radiometers, and the High Frequency Instrument (HFI) with bolometers operating at 100 mK. After the successful launch in May 2009, Planck has already mapped the sky twice (at the time of writing this review) with the expected behavior and it is planned to complete at least two further all-sky surveys. The first scientific results, consisting of an Early Release Compact Source Catalog (ERCSC) and in about twenty papers on instrument performance in flight, data analysis pipeline, and main astrophysical results, will be released on January 2011. The first publications of the main cosmological implications are expected in 2012.

Polarization and wavelength are the bits of information attached to every photon that reveal the most about its formation and subsequent history. The E-ELT will, for the foreseeable future, be the most powerful optical light-collecting machine ever built. The strength of its combination, spectropolarimetry with the E-ELT, is the anchorage in physics of astronomical observations. I present a strawman design of a spectropolarimeter for its intermediate focus.

The coming years will see routine use of solar data of unprecedented spatial and spectral resolution, time cadence, and completeness in the wavelength domain. To capitalize on the soon to be available radio facilities such as the expanded OVSA, SSRT and FASR, and the challenges they present in the visualization and synthesis of the multi-frequency datasets, we propose that realistic, sophisticated 3D active region and flare modeling is timely now and will be a forefront of coronal studies over the coming years. Here we summarize our 3D modeling efforts, aimed at forward fitting of imaging spectroscopy data, and describe currently available 3D modeling tools. We also discuss plans for future generalization of our modeling tools.

The ALMA (Atacama Large Millimeter/sub-millimeter Array) is the large interferometer that will consist up to 64 high-precision antennas operating in the 31.3 – 950 GHz frequency range. In this range unique observations in cosmology, cold universe, galaxies, stars and their formations, and so on are expected. Among these objectives there is a unique possibility to observe the Sun and to address outstanding issues of solar physics. The ALMA is shortly described and then the new ESO-ALMA European node (ARC) built at Ondřejov Observatory is presented. The new ARC is the only one in Europe oriented to solar physics. The requirements and limitations for ALMA solar observations, as well as some examples of possible solar-oriented ALMA projects, are mentioned.

The Sun is a plasma laboratory for astrophysics, which allows us to investigate many important phenomena in turbulent magnetized plasma in detail. Solar Dynamics Observatory (SDO) launched in February 2010 provides unique information about plasma processes from the interior to the corona. The primary processes of magnetic field generation and formation of magnetic structures are hidden beneath the visible surface. Helioseismic diagnostics, based on observations and analysis of solar oscillations and waves, give insights into the physical processes in the solar interior and mechanisms of solar magnetic activity. In addition, simultaneous high-resolution multi-wavelength observations of the solar corona provide opportunity to investigate in unprecedented detail the coronal dynamics and links to the interior processes. These capabilities are illustrated by initial results on the large-scale dynamics of the Sun, the subsurface structure and dynamics of a sunspot and observations of a X-class solar flare.

We present an extension of the Unno-Rachkovsky solution that provides the theoretical profiles coming out of a Milne-Eddington atmosphere imbedded in a magnetic field, to the additional taking into account of a vertical velocity gradient. Thus, the theoretical profiles may display asymmetries as do the observed profiles, which facilitates the inversion based on the Unno-Rachkovsky theory, and leads to the additional determination of the vertical velocity gradient. We present UNNOFIT inversion on spectropolarimetric data performed on an active region of the Sun with the french-italian telescope THEMIS operated by CNRS and CNR on the island of Tenerife.

Observations of plasma and magnetic field fluctuations in the solar wind provide a valuable source of information for the study of turbulence in collisionless astrophysical plasmas. Scientific data collected by various spacecraft over the last few decades has fueled steady progress in this field. Theoretical models, numerical simulations, and comparisons between theory and experiment have also contributed greatly to these advances. This review highlights some recent advances on the observational side including measurements of the anisotropy of inertial range fluctuations as revealed by the different scaling laws parallel and perpendicular to the mean magnetic field, measurements of the normalized cross-helicity spanning the entire inertial range which demonstrate that this quantity is scale invariant, and improved measurements of the spectrum of magnetic field fluctuations in the dissipation range that show a spectral break near the lengthscale of the electron gyro-radius. The theoretical implications of these results and comparisons between theory and observations are briefly summarized.

Based on the three-fluid approximation the influence of the neutral component of hydrogen plasma on Joule dissipation of electric currents are considered. As distinguished from Mestel & Spitzer (1956) and Parker (1963) it has been shown that the magnetic flux may be not conserved in the case of the “ambipolar diffusion” due to collisions between ions and neutrals. This is explained by the ion acceleration under the action of Ampere's force. Joule dissipation is determined by electron and ion collisions in a partially ionized plasma. Plasma evacuation from current sheets is the effective mechanism of its cooling. Thickness of a current sheet can achieve up to hundreds of kilometers in the solar chromosphere. The origin of the solar chromospheric jets observed with the Hinode satellite are discussed.

We present a unified three-dimensional model of the convection zone and upper atmosphere of the Sun in spherical geometry. In this model, magnetic fields, generated by a helically forced dynamo in the convection zone, emerge without the assistance of magnetic buoyancy. We use an isothermal equation of state with gravity and density stratification. Recurrent plasmoid ejections, which rise through the outer atmosphere, is observed. In addition, the current helicity of the small–scale field is transported outwards and form large structures like magnetic clouds.

EST European Solar Telescope is a pan-european project, presently in its Conceptual Design Study financed by the European Commission in the framework of FP7, involving 29 partners, from 14 different countries. The EST project is aimed at the realization of a 4-m class telescope, characterized by an optical design and a set of instruments optimized for extremely high resolution imaging and spectropolarimetric observations from near UV to NIR. EST will be four times larger than any existing high resolution solar telescope and it is designated with the highest priority among the ground-based, medium term (2016-2020) new projects in the ASTRONET Roadmap (Panel C). The EST instruments will measure fundamental astrophysical processes at their intrinsic scales in the Sun's atmosphere to establish the mechanism of magnetic field generation and removal, and of energy transfer from the surface to the upper solar atmosphere and eventually to the whole heliosphere. The conceptual Design Study started on February 2008 and will finish during 2011. EST will be operational at the same time as major ESA and NASA space missions aimed at studying solar activity.

Gyrosynchrotron (GS) emission of charged particles spiraling in magnetic fields plays an exceptionally important role in astrophysics. In particular, this mechanism makes a dominant contribution to the continuum solar and stellar radio emissions. However, the available exact equations describing the emission process are extremely slow computationally, thus limiting the diagnostic capabilities of radio observations. In this work, we present approximate GS codes capable of fast calculating the emission from anisotropic electron distributions. The computation time is reduced by several orders of magnitude compared with the exact formulae, while the computation error remains within a few percent. The codes are implemented as the executable modules callable from IDL; they are made available for users via web sites.

Instabilities of nonuniform flows is a fundamental problem in dynamics of fluids and plasmas. This presentation outlines atypical dynamics of instabilities for unmagnetized and magnetized astrophysical differentially rotating flows, including, our efforts in the development of general theory of magneto rotation instability (MRI) that takes into account plasma compressibility, pressure anisotropy, dissipative and kinetic effects. Presented analysis of instability (transient growth) processes in unmagnetized/hydrodynamic astrophysical disks is based on the breakthrough of the hydrodynamic community in the 1990s in the understanding of shear flow non-normality induced dynamics. This analysis strongly suggests that the so-called bypass concept of turbulence, which has been developed by the hydrodynamic community for spectrally stable shear flows, can also be applied to Keplerian disks. It is also concluded that the vertical stratification of the disks is an important ingredient of dynamical processes resulting onset of turbulence.

The strength and structure of cosmic magnetic fields is best studied by observations of radio continuum emission, its polarization and its Faraday rotation. Fields with a well-ordered spiral structure exist in many types of galaxies. Total field strengths in spiral arms and bars are 20–30 μG and dynamically important. Strong fields in central regions can drive gas inflows towards an active nucleus. The strongest regular fields (10–15 μG) are found in interarm regions, sometimes forming “magnetic spiral arms” between the optical arms. The typical degree of polarization is a few % in spiral arms, but high (up to 50%) in interarm regions. The detailed field structures suggest interaction with gas flows. Faraday rotation measures of the polarization vectors reveals large-scale patterns in several spiral galaxies which are regarded as signatures of large-scale (coherent) fields generated by dynamos. – Polarization observations with the forthcoming large radio telescopes will open a new era in the observation of magnetic fields and should help to understand their origin. Low-frequency radio synchrotron emission traces low-energy cosmic ray electrons which can propagate further away from their origin. LOFAR (30–240 MHz) will allow us to map the structure of weak magnetic fields in the outer regions and halos of galaxies, in galaxy clusters and in the Milky Way. Polarization at higher frequencies (1–10 GHz), to be observed with the EVLA, MeerKAT, APERTIF and the SKA, will trace magnetic fields in the disks and central regions of galaxies in unprecedented detail. All-sky surveys of Faraday rotation measures towards a dense grid of polarized background sources with ASKAP and the SKA are dedicated to measure magnetic fields in distant intervening galaxies and clusters, and will be used to model the overall structure and strength of the magnetic field in the Milky Way.

The transport of magnetic flux to outside of collapsing molecular clouds is a required step to allow the formation of stars. Although ambipolar diffusion is often regarded as a key mechanism for that, it has been recently argued that it may not be efficient enough. In this review, we discuss the role that MHD turbulence plays in the transport of magnetic flux in star forming flows. In particular, based on recent advances in the theory of fast magnetic reconnection in turbulent flows, we will show results of three-dimensional numerical simulations that indicate that the diffusion of magnetic field induced by turbulent reconnection can be a very efficient mechanism, especially in the early stages of cloud collapse and star formation. To conclude, we will also briefly discuss the turbulence-star formation connection and feedback in different astrophysical environments: from galactic to cluster of galaxy scales.

The first detection of a diffuse radio source in a cluster of galaxies, dates back to the 1959 (Coma Cluster, Large et al. 1959). Since then, synchrotron radiating radio sources have been found in several clusters, and represent an important cluster component which is linked to the thermal gas. Such sources indicate the existence of large scale magnetic fields and of a population of relativistic electrons in the cluster volume. The observational results provide evidence that these phenomena are related to turbulence and shock-structures in the intergalactic medium, thus playing a major role in the evolution of the large scale structure in the Universe. The interaction between radio sources and cluster gas is well established in particular at the center of cooling core clusters, where feedback from AGN is a necessary ingredient to adequately describe the formation and evolution of galaxies and host clusters.

The fractal shape and multi-component nature of the interstellar medium together with its vast range of dynamical scales provides one of the great challenges in theoretical and numerical astrophysics. Here we will review recent progress in the direct modelling of interstellar hydromagnetic turbulence, focusing on the role of energy injection by supernova explosions. The implications for dynamo theory will be discussed in the context of the mean-field approach.

Results obtained with the test field-method are confronted with analytical predictions and estimates from quasilinear theory. The simulation results enforce the classical understanding of a turbulent Galactic dynamo and, more importantly, yield new quantitative insights. The derived scaling relations enable confident global mean-field modelling.

We present recent developments of global galactic-scale numerical models of the Cosmic Ray (CR) driven dynamo, which was originally proposed by Parker (1992). We conduct a series of direct CR+MHD numerical simulations of the dynamics of the interstellar medium (ISM), composed of gas, magnetic fields and CR components. We take into account CRs accelerated in randomly distributed supernova (SN) remnants, and assume that SNe deposit small-scale, randomly oriented, dipolar magnetic fields into the ISM. The amplification timescale of the large-scale magnetic field resulting from the CR-driven dynamo is comparable to the galactic rotation period. The process efficiently converts small-scale magnetic fields of SN-remnants into galactic-scale magnetic fields. The resulting magnetic field structure resembles the X-shaped magnetic fields observed in edge-on galaxies.

Interpretation of current and future data calls for a continuous improvement in the theoretical modeling of CMB spectrum. We describe the new version of a numerical code, KYPRIX, specifically written to solve the Kompaneets equation in a cosmological context under general assumptions. We report on the equation formalism, and structure and computational aspects of the code. New physical options have been introduced in the current code version: the cosmological constant in the terms controlling the general expansion of the Universe, the relevant chemical abundances, and the ionization history, from recombination to cosmological reionization. We present some of fundamental tests we carried out to verify the accuracy, reliability, and performance of the code. All the tests demonstrate the reliability and versatility of the new code version and its accuracy and applicability to the scientific analysis of current CMB spectrum data and of much more precise measurements that will be available in the future.

MHD Turbulence is a critical component of the current paradigms of star formation, particle transport, magnetic reconnection and evolution of the ISM, to name just a few. Progress on this difficult subject is made via numerical simulations and observational studies, however in order to connect these two, statistical methods are required. This calls for new statistical tools to be developed in order to study turbulence in the interstellar medium. Here we briefly review some of the recently developed statistics that focus on characterizing gas compressibility and magnetization and their uses to interstellar studies.