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Active Galactic Nuclei, Radio Jets and Acceleration of UHECRs
S. Massaglia
We present the general properties of the Active Galactic Nuclei (AGNs) and discuss the origin and structure of jets that are associated to a fraction of these objects. We then we a…
Simulating radiative astrophysical flows with the PLUTO code: A non-equilibrium, multi-species cooling function
O. Tesileanu, A. Mignone, S. Massaglia
Time-dependent cooling processes are of paramount importance in the evolution of astrophysical gaseous nebulae and, in particular, when radiative shocks are present. The present wo…
Formation of dynamical structures in relativistic jets: the FRI case
P. Rossi, A. Mignone, G. Bodo +2
Strong observational evidence indicates that all extragalactic jets associated with AGNs move at relativistic speed up to 100 pc - 1 kpc scales from the nucleus. At larger distance…
On the linear theory of Kelvin-Helmholtz instabilities of relativistic magnetohydrodynamic planar flows
Z. Osmanov, A. Mignone, S. Massaglia +2
We investigate the linear stability properties of the plane interface separating two relativistic magnetized flows in relative motion. The two flows are governed by the (special) r…
Two-component jet simulations: I. Topological stability of analytical MHD outflow solutions
T. Matsakos, K. Tsinganos, N. Vlahakis +3
Observations of collimated outflows in young stellar objects indicate that several features of the jets can be understood by adopting the picture of a two-component outflow, wherei…
MHD simulations of jet acceleration from Keplerian accretion disks: the effects of disk resistivity
C. Zanni, A. Ferrari, R. Rosner +2
Accretion disks and astrophysical jets are used to model many active astrophysical objects, viz., young stars, relativistic stars, and active galactic nuclei. In this paper we pres…
PLUTO: a Numerical Code for Computational Astrophysics
A. Mignone, G. Bodo, S. Massaglia +4
We present a new numerical code, PLUTO, for the solution of hypersonic flows in 1, 2 and 3 spatial dimensions and different systems of coordinates. The code provides a multi-physic…
Relativistic MHD Simulations of Jets with Toroidal Magnetic Fields
A. Mignone, S. Massaglia, G. Bodo
This paper presents an application of the recent relativistic HLLC approximate Riemann solver by Mignone & Bodo to magnetized flows with vanishing normal component of the magnetic…
Time-Dependent MHD Shocks and Line Emission: The Case of the DG Tau Jet
S. Massaglia, A. Mignone, G. Bodo
The line emission from a growing number of Herbig-Haro jets can be observed and resolved at angular distances smaller than a few arcseconds from the central source. The interpretat…
Heating groups and clusters of galaxies: the role of AGN jets
C. Zanni, G. Murante, G. Bodo +3
X-Ray observations of groups and clusters of galaxies show that the Intra-Cluster Medium (ICM) in their cores is hotter than expected from cosmological numerical simulations of clu…
X-ray emission from expanding cocoons
C. Zanni, G. Bodo, P. Rossi +3
X-ray observations of extragalactic radiosources show strong evidences of interaction between the radio emitting plasma and the X-ray emitting ambient gas. In this paper we perform…
Constraining the Parameters of AGN Jets - Comparisons with Herbig-Haro Jets
Silvano Massaglia
Comparing the properties AGN and Herbig-Haro jets can be a useful exercise for understanding the physical mechanisms at work in collimated outflows that propagate in such different…
Swirling astrophysical flows - efficient amplifiers of Alfven waves
Andria D. Rogava, Swadesh M. Mahajan, Gianluigi Bodo +1
We show that a helical shear flow of a magnetized plasma may serve as an efficient amplifier of Alfven waves. We find that even when the flow is purely ejectional (i.e., when no ro…
On the origin of X-shaped radio-sources: new insights from the properties of their host galaxies
A. Capetti, S. Zamfir, P. Rossi +3
A significant fraction of extended radio sources presents a peculiar X-shaped radio morphology: in addition to the classical double lobed structure, radio emission is also observed…
The hard X-ray emission from the complex SNR MSH 15-52 observed by BeppoSAX
T. Mineo, G. Cusumano, M. C. Maccarone +3
We present the results of a BeppoSAX observation of the Supernova Remnant MSH 15-52, associated with the pulsar PSR B1509-58, and discuss its main morphological and spectroscopic p…
BeppoSAX observation of Hercules A and MRC 0625-536
E. Trussoni, L. Feretti, S. Massaglia +1
We present BeppoSAX observations of the two FR I type radio galaxies Hercules A (3C 348) and MRC 0625-536 in the energy range keV. Data analysis shows that the X-ray fl…
EVN Observations of GRS1915+105
L. Feretti, G. Giovannini, M. Tordi +12
We obtained EVN observations of the X-ray transient source GRS1915+105 in its radio-loud state. In 2 images obtained before a major flare, the source is resolved, showing two oppos…
On the matter entrainment by stellar jets and the acceleration of molecular outflows
M. Micono, G. Bodo, S. Massaglia +2
We study, by numerical simulations, the entrainment process in a supersonic, radiative jet flow, during the evolution of Kelvin-Helmholtz instabilities, in the context of the the a…
Kelvin-Helmholtz instability in three dimensional radiative jets
M. Micono, G. Bodo, S. Massaglia +3
The analysis of the stability properties of astrophysical jets against Kelvin-Helmholtz (or shear-layer) instabilities plays a basic role in the understanding the origin and physic…
Understanding NLR in Seyfert Galaxies: numerical simulation of jet-cloud interaction
P. Rossi, A. Capetti, G. Bodo +2
Recent HST observations suggest that the NLR in Seyfert Galaxies can be the result of interaction between jet and external inhomogeneous medium; following this suggestion we perfor…
Acoustic Waves in a Stratified Atmosphere: II. Three-Dimensional Hydrodynamics
G. Bodo, W. Kalkofen, S. Massaglia +1
We investigate analytically the propagation of linear waves in a three-dimensional, nonmagnetic, isothermal atmosphere stratified in plane-parallel layers. The motivation is to stu…
Diffusive shock acceleration in extragalactic jets
M. Micono, N. Zurlo, S. Massaglia +2
We calculate the temporal evolution of distributions of relativistic electrons subject to synchrotron and adiabatic processes and Fermi-like acceleration in shocks. The shocks resu…
BeppoSAX observations of low power radio galaxies: possible detection of obscured nuclei
E. Trussoni, F. Vagnetti, S. Massaglia +6
We present the first results of BeppoSAX observations of a small sample of low brightness FRI radio galaxies. The flux of all the targets is consistent with a thermal spectrum, as…
Dynamical and radiative properties of astrophysical supersonic jets I. Cocoon morphologies
S. Massaglia, G. Bodo, A. Ferrari
We present the results of a numerical analysis of the propagation and interaction of a supersonic jet with the external medium. We discuss the motion of the head of the jet into th…