scholarly journals Three‐dimensional Simulations of Spherical Accretion Flows with Small‐Scale Magnetic Fields

2006 ◽  
Vol 649 (1) ◽  
pp. 361-372 ◽  
Author(s):  
Igor V. Igumenshchev
Keyword(s):  
Magnetic Fields ◽  
Three Dimensional ◽  
Small Scale ◽  
Accretion Flows ◽  
Three Dimensional Simulations

scholarly journals The Fermi bubbles inflated by winds from the accretion flow in Sgr A*

2014 ◽  
Vol 10 (S312) ◽  
pp. 137-138
Author(s):  
Guobin Mou
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Small Scale ◽  
Observational Constraints ◽  
Accretion Flow ◽  
Accretion Flows ◽  
The Past ◽  
Sgr A ◽  
Hydrodynamical Simulations

AbstractBy performing three-dimensional hydrodynamical simulations, we show that the Fermi bubbles could be inflated by winds launched from the “past” hot accretion flow in Sgr A*. The parameters of the accretion flow required in the model are consistent with those obtained independently from other observational constraints. The wind parameters are taken from small scale MHD numerical simulations of hot accretion flows.

scholarly journals Numerical simulations of Hall MHD small-scale dynamos

2009 ◽  
Vol 5 (H15) ◽  
pp. 436-437
Author(s):  
Daniel O. Gómez ◽  
Pablo D. Mininni ◽  
Pablo Dmitruk
Keyword(s):  
Numerical Simulations ◽  
Hall Effect ◽  
Three Dimensional ◽  
Theoretical Framework ◽  
Mhd Equations ◽  
Small Scale ◽  
Hall Parameter ◽  
Hall Mhd ◽  
Three Dimensional Simulations

AbstractMuch of the progress in our understanding of dynamo mechanisms, has been made within the theoretical framework of magnetohydrodynamics (MHD). However, for sufficiently diffuse media, the Hall effect eventually becomes non-negligible. We present results from three dimensional simulations of the Hall-MHD equations subjected to random non-helical forcing. We study the role of the Hall effect in the dynamo efficiency for different values of the Hall parameter, using a pseudospectral code to achieve exponentially fast convergence.

scholarly journals Three-dimensional Simulations of Accretion to Stars with Complex Magnetic Fields

2008 ◽  
Author(s):  
M. Long ◽  
M. M. Romanova ◽  
R. V. E. Lovelace ◽  
Rudy Wijnands ◽  
Diego Altamirano ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Three Dimensional ◽  
Three Dimensional Simulations

scholarly journals Vector Potential Magnetic Null Points

1991 ◽  
Vol 130 ◽  
pp. 89-91
Author(s):  
Klaus Galsgaard ◽  
Åke Nordlund
Keyword(s):  
Fractal Dimension ◽  
Magnetic Fields ◽  
Energy Release ◽  
Large Range ◽  
Solar Surface ◽  
Three Dimensional ◽  
Small Scale ◽  
Surface Distribution ◽  
Self Similar ◽  
Magnetic Null

Recent observations (Tarbell et al., 1990; see also Ruzmaikin et al. these Proceedings) show that the surface distribution of magnetic fields on the solar surface is selfsimilar, with an approximately constant fractal dimension over a large range of horizontal scales. Also, recent ideas about flare energy release assumes a “fibrous” corona, with the energy release consisting of many small scale events (Vlahoz, 1989) Prompted partly by these observations, we investigate the properties of self-similar three-dimensional magnetic fields.

scholarly journals Magneto-convection

2012 ◽  
Vol 370 (1970) ◽  
pp. 3070-3087 ◽  
Author(s):  
Robert F. Stein
Keyword(s):  
Magnetic Fields ◽  
Equations Of State ◽  
Three Dimensional ◽  
Dynamo Action ◽  
Spatial And Temporal Scales ◽  
Solar Observations ◽  
Wide Range ◽  
Induction Equation ◽  
The Magnetic Field ◽  
Three Dimensional Simulations

Convection is the transport of energy by bulk mass motions. Magnetic fields alter convection via the Lorentz force, while convection moves the fields via the curl( v × B ) term in the induction equation. Recent ground-based and satellite telescopes have increased our knowledge of the solar magnetic fields on a wide range of spatial and temporal scales. Magneto-convection modelling has also greatly improved recently as computers become more powerful. Three-dimensional simulations with radiative transfer and non-ideal equations of state are being performed. Flux emergence from the convection zone through the visible surface (and into the chromosphere and corona) has been modelled. Local, convectively driven dynamo action has been studied. The alteration in the appearance of granules and the formation of pores and sunspots has been investigated. Magneto-convection calculations have improved our ability to interpret solar observations, especially the inversion of Stokes spectra to obtain the magnetic field and the use of helioseismology to determine the subsurface structure of the Sun.

scholarly journals Studying Magnetic Fields using Low-frequency Pulsar Observations

2017 ◽  
Vol 13 (S337) ◽  
pp. 299-303
Author(s):  
C. Sobey ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Galactic Halo ◽  
Three Dimensional ◽  
Low Frequency ◽  
Small Scale ◽  
Radio Telescopes ◽  
Astrophysical Plasmas ◽  
Murchison Widefield Array

AbstractLow-frequency polarisation observations of pulsars, facilitated by next-generation radio telescopes, provide powerful probes of astrophysical plasmas that span many orders of magnitude in magnetic field strength and scale: from pulsar magnetospheres to intervening magneto-ionic plasmas including the ISM and the ionosphere. Pulsar magnetospheres with teragauss field strengths can be explored through their numerous emission phenomena across multiple frequencies, the mechanism behind which remains elusive. Precise dispersion and Faraday rotation measurements towards a large number of pulsars probe the three-dimensional large-scale (and eventually small-scale) structure of the Galactic magnetic field, which plays a role in many astrophysical processes, but is not yet well understood, especially towards the Galactic halo. We describe some results and ongoing work from the Low Frequency Array (LOFAR) and the Murchison Widefield Array (MWA) radio telescopes in these areas. These and other pathfinder and precursor telescopes have reinvigorated low-frequency science and build towards the Square Kilometre Array (SKA), which will make significant advancements in studies of astrophysical magnetic fields in the next 50 years.

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