Jets are one of the more dramatic and visible manifestations of black hole accretion. It is becoming increasingly accepted that magnetic fields underlie the mechanism behind the launching of relativistic jets. At the same time it is now appreciated that the fundamental driving mechanism behind accretion is due to magnetohydrodynamical processes and the stresses they engender. Global disk simulations in full general relativity have begun to reveal the radial dependence of disk stresses and the intimate connections between accretion and jet-launching. This talk will review the issues involved, the recent progress that has been made, and the challenges that remain.

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.

Our numerical simulations show that the reconnection of magnetic field becomes fast in the presence of weak turbulence in the way consistent with the Lazarian & Vishniac (1999) model of fast reconnection. This process in not only important for understanding of the origin and evolution of the large-scale magnetic field, but is seen as a possibly efficient particle accelerator producing cosmic rays through the first order Fermi process. In this work we study the properties of particle acceleration in the reconnection zones in our numerical simulations and show that the particles can be efficiently accelerated via the first order Fermi acceleration.

Recently it has become apparent that proto-stellar-like outflow activity extends to the brown dwarf (BD) mass regime. While the presence of accretion appears to be the common ingredient in all objects known to drive jets fundamental questions remain unanswered. The more prominent being the exact mechanism by which jets are launched, and whether this mechanism remains universal among such a diversity of sources and scales. To address these questions we have been investigating outflow activity in a sample of protostellar objects that differ considerably in mass and mass accretion rate. Central to this is our study of brown dwarf jets. To date Classical T Tauri stars (CTTS) have offered us the best touchstone for decoding the launching mechanism. Here we shall summarise what is understood so far of BD jets and the important constraints observations can place on models. We will focus on the comparison between jets driven by objects with central mass <0.1M⊙ and those driven by CTTSs. In particular we wish to understand how the the ratio of the mass outflow to accretion rate compares to what has been measured for CTTSs.

Solar prominences can be viewed as pre-eruptive states of coronal mass ejections (CMEs). Eruptive prominences are the phenomena most related to CMEs observed in the lower layers of the solar atmosphere. We have made a comprehensive statistical study on the CMEs associated with prominence eruptions. We have examined the distribution of CMEs speed and acceleration for prominence eruptions associated CMEs. We also examine the speed-acceleration correlation for these events and there is no correlation between speed and acceleration. The mean angular width is almost similar to normal CMEs. The number variation during solar cycle of prominence activities is similar to the sunspot cycle.

We propose a modeling study on the formation and evolution of the Circumstellar Envelopes (CSEs) of a sample of selected radio-loud objects, based on an innovative interaction between two codes widely used by the scientific community, but in different fields. CLOUDY (Ferland et al. 1998) is a widely used code to model the spectral energy distribution (SED) of the several objects characterized by clouds of gas heated and ionized by a central object. CosmoMC (Lewis & Bridle 2002) instead is usually used for exploring cosmological parameter space. We investigate here on the exploitation of the sampling performance of the Markov-Chain Monte-Carlo (MCMC) engine of CosmoMC to search for a best fit model of the considered objects through the spectral synthesis capacity of CLOUDY.

Acceleration processes at astrophysical collisionless shocks are reviewed with a special emphasis on the importance of in situ observations of heliospheric shocks. Topics to be included are nonlinear reaction of shock acceleration process, effect of neutral particles, and electron acceleration.

We test the stability of a magnetic equilibrium configuration using numerical simulations and semi-analytical tools. The tested configuration is, as described by Duez & Mathis (2010), the lowest energy state for a given helicity in a stellar radiation zone. We show using 3D magneto-hydrodynamic (MHD) simulations that the present configuration is stable with respect to all submitted perturbations, that would lead to the development of kink-type instabilities in the case of purely poloidal or toroidal fields, both well known to be unstable. We also discuss, using semi-analytic work, the stabilizing influence of one component on the other and show that the found configuration actually lies in the stability domain predicted by a linear analysis of resonant modes.

We studied numerically electron acceleration by a perpendicular wavy shock. Distribution function of accelerated electrons is highly anisotropic, with many sharp peaks. The peaks are caused by (usually single) reflections of electrons by the shock and subsequent transmission.

In the present investigation, radial diffusion of equatorially trapped electrons in the magnetospheres of Jupiter and Rotating Radio Transients (RRATs) are examined and compared. It is assumed that electrons lose energy through synchrotron radiation and the wave-particle interaction. The phase space density of the electrons, which go through gradB drift in Jupiter's and RRATs magnetospheres and thus resonate with the plasma waves, changes and this change predicted by the model seems to be consistent with the Pioneer 10 and Pioneer 11 data for Jupiter's case and a similar result obtained for RRATs.

We performed mapping observations of the Fornax A west lobe with Suzaku in order to measure X-ray brightness distribution. Thanks to the low and stable background of Suzaku, we succeeded in detecting the faint diffuse X-ray emission from the west lobe. Performing careful corrections to the obtained images, we finally measured the X-ray brightness profile extending over the lobe. By comparing the X-ray and radio profiles, the magnetic field found to be fairly constant at ~1 μG over the lobe, while the electron energy distribution is suggested to concentrate on the lobe center.

Magnetic fields are a distinctive feature of accretion disc plasmas around compact objects (i.e., black holes and neutron stars) and they play a decisive role in their dynamical evolution. A fundamental theoretical question related with this concerns investigation of the so-called gravitational MHD dynamo effect, responsible for the self-generation of magnetic fields in these systems. Experimental observations and theoretical models, based on fluid MHD descriptions of various types support the conjecture that accretion discs should be characterized by coherent and slowly time-varying magnetic fields with both poloidal and toroidal components. However, the precise origin of these magnetic structures and their interaction with the disc plasmas is currently unclear. The aim of this paper is to address this problem in the context of kinetic theory. The starting point is the investigation of a general class of Vlasov-Maxwell kinetic equilibria for axi-symmetric collisionless magnetized plasmas characterized by temperature anisotropy and mainly toroidal flow velocity. Retaining finite Larmor-radius effects in the calculation of the fluid fields, we show how these configurations are capable of sustaining both toroidal and poloidal current densities. As a result, we suggest the possible existence of a kinetic dynamo effect, which can generate a stationary toroidal magnetic field in the disc even without any net radial accretion flow. The results presented may have important implications for equilibrium solutions and stability analysis of accretion disc dynamics.

Most of jets detected in AGN blazar sources exhibit a morphological structure usually composed by a spatially unresolved core and jet knots receding from it at relativistic velocities. In some cases, the trajectories of the jet components on the plane of the sky seem to be bent, indicating the existence of some kind of acceleration in the respective motion. However, such claims depend strongly on the correct determination of the structural parameters of the jet components, usually obtained from model fitting procedures performed either in the (u,v) or in the image planes. In this work we introduce a new model fitting technique to obtain structural parameters of knots present in VLBI jet images. Our method that is based on the cross-entropy technique minimises an performance function that depends on the sum of the squared residuals obtained from the comparison of an VLBI image and a model image, constructed by summing Ns elliptical Gaussian synthetic sources. We present in this work the cross-entropy model fittings of benchmark images that were built to simulate most of the conditions encountered in typical VLBI images of active galactic nuclei. Besides recovering the parameters of the jet components in all validation tests, our method is able to point out quantitatively the number of the sources present in the image.

Jets from accreting black holes appear remarkably similar over eight orders of magnitude in black hole mass, with more massive black holes generally launching more powerful jets. For example, there is an observed correlation, termed the fundamental plane of black hole accretion, between black hole mass, radio luminosity, and X-ray luminosity. Here, we probe the high-mass tail (108–109M⊙) of the accreting black hole distribution with BL Lac objects. We build SEDs for hundreds of SDSS BL Lacs, and we use these SEDs to test the blazar sequence, a proposed anti-correlation between jet power and peak frequency. We then show our BL Lacs fit on the fundamental plane, supporting the non-linear scaling of jet radiation with black hole mass. The subset of BL Lacs considered here compose the largest sample yet used in the above types of studies, reducing potential selection effects and biases.

Accreting neutron stars can produce jets only if they are weakly magnetized (B ~ 108 G). On the other hand, neutron stars are compact objects born with strong surface magnetic fields (B ~ 1012 G). In this work we study the conditions for jet formation in a binary system formed by a neutron star and a massive donor star once the magnetic field has decayed due to accretion. We solve the induction equation for the magnetic field diffusion in a realistic neutron star crust and discuss the possibility of jet launching in systems like the recently detected Supergiant Fast X-ray Transients.

A concise review of the past and ongoing laboratory experiments on rotating flows and the associated angular momentum transport relevant to astrophysical disks is given in three categories: hydrodynamic, magnetohydrodynamic, gas and plasma experiments. Future prospects for these experiments, especially for those directly relevant to the magnetorotational instability (MRI), are discussed with an emphasis on a newly proposed swirling gas and plasma experiment.

In 1974 Fanaroff & Riley divided the extended radio sources into two classes, on the basis of their radio morphology and power. For several years we have been collecting basic parameters for extragalactic jets detected in the X-rays, looking for an extension of the classification criterion, based on their radio and X-rays properties. The fact that different processes have been proposed to explain their X-ray radiation, (synchrotron vs inverse Compton emission) suggests the possibility of a new classification scheme. However, comparing the radio-to-X-ray properties of the extragalactic jets, several aspects on their nature became unexpectedly unclear.

Narrow-Line Seyfert 1 (NLS1) class of active galactic nuclei (AGNs) is generally radio-quiet, but a small percent of them are radio-loud. The recent discovery by Fermi/LAT of high-energy γ-ray emission from 4 NLS1s proved the existence of relativistic jets in these systems. It is therefore important to study this new class of γ-ray emitting AGNs. Here we report preliminary results about the observations of the July 2010 γ-ray outburst of PMN J0948+0022, when the source flux exceeded for the first time 10−6 ph cm−2 s−1 (E > 100 MeV).

Waves propagating obliquely in a magnetized cold pair plasma experience an approximate resonance in the wavevector component perpendicular to the magnetic field, which is the analogue of the Alfvén resonance in normal electron-ion plasmas. Wave absorption at the resonance can take place via mode conversion to the analogue of the short wavelength inertial Alfvén wave. The Alfvén resonance could play a role in wave propagation in the pulsar magnetosphere leading to pulsar radio emission. Ducting of waves in strong plasma gradients may occur in the pulsar magnetosphere, which leads to the consideration of Alfvén surface waves, whose energy is concentrated in the region of strong gradients.

We perform 3D numerical simulations of footpoint-driven transverse waves propagating in a low β plasma. The presence of inhomogeneities in the density profile leads to the coupling of the driven kink mode to Alfvén modes by resonant absorption. The decay of the propagating kink wave as energy is transferred to the local Alfvén mode is in good agreement with a modified interpretation of the analytical expression derived for standing kink modes. This coupling may account for the damping of transverse velocity perturbation waves which have recently been observed to be ubiquitous in the solar corona.