Generation of Magnetic Fields by Radiation Pressure from the First Stars

2010 ◽  
Author(s):  
Hajime Susa ◽  
Masashi Ando ◽  
Kentaro Doi ◽  
Daniel J. Whalen ◽  
Volker Bromm ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Radiation Pressure ◽  
First Stars

Primordial Magnetic Fields: Reionization Constraints and Implications for the First Stars

2010 ◽  
Author(s):  
Dominik R. G. Schleicher ◽  
Robi Banerjee ◽  
Simon C. O. Glover ◽  
Daniele Galli ◽  
Francesco Palla ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
First Stars ◽  
Primordial Magnetic Fields

scholarly journals The importance of magnetic fields for the initial mass function of the first stars

2020 ◽  
Vol 497 (1) ◽  
pp. 336-351 ◽  
Author(s):  
Piyush Sharda ◽  
Christoph Federrath ◽  
Mark R Krumholz
Keyword(s):  
Magnetic Fields ◽  
Initial Conditions ◽  
High Redshift ◽  
Three Dimensional ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Dynamo Theory ◽  
First Stars ◽  
High Redshift Galaxies

ABSTRACT Magnetic fields play an important role for the formation of stars in both local and high-redshift galaxies. Recent studies of dynamo amplification in the first dark matter haloes suggest that significant magnetic fields were likely present during the formation of the first stars in the Universe at redshifts of 15 and above. In this work, we study how these magnetic fields potentially impact the initial mass function (IMF) of the first stars. We perform 200 high-resolution, three-dimensional (3D), magnetohydrodynamic (MHD) simulations of the collapse of primordial clouds with different initial turbulent magnetic field strengths as predicted from turbulent dynamo theory in the early Universe, forming more than 1100 first stars in total. We detect a strong statistical signature of suppressed fragmentation in the presence of strong magnetic fields, leading to a dramatic reduction in the number of first stars with masses low enough that they might be expected to survive to the present-day. Additionally, strong fields shift the transition point where stars go from being mostly single to mostly multiple to higher masses. However, irrespective of the field strength, individual simulations are highly chaotic, show different levels of fragmentation and clustering, and the outcome depends on the exact realization of the turbulence in the primordial clouds. While these are still idealized simulations that do not start from cosmological initial conditions, our work shows that magnetic fields play a key role for the primordial IMF, potentially even more so than for the present-day IMF.

scholarly journals On the influence of magnetic fields in neutral planetary wakes

2016 ◽  
Vol 12 (S328) ◽  
pp. 192-197
Author(s):  
C. Villarreal D’Angelo ◽  
M. Schneiter ◽  
A. Esquivel
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Magnetic Moments ◽  
Radiative Processes ◽  
Planetary Magnetic Fields ◽  
Stellar Magnetic Fields

AbstractWe present a 3D magnetohydrodynamic study of the effect that stellar and planetary magnetic fields have on the calculated Lyα absorption during the planetary transit, employing parameters that resemble the exoplanet HD209458b. We assume a dipolar magnetic field for both the star and the planet, and use the Parker solution to initialize the stellar wind. We also consider the radiative processes and the radiation pressure.We use the numerical MHD code Guacho to run several models varying the values of the planetary and stellar magnetic moments within the range reported in the literature.We found that the presence of magnetic fields influences the escaping neutral planetary material spreading the absorption Lyα line for large stellar magnetic fields.

scholarly journals MHD Models of Planetary Nebulae: Review

2003 ◽  
Vol 209 ◽  
pp. 457-464 ◽  
Author(s):  
Guillermo García-Segura
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Ab Initio ◽  
Radiation Pressure ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Basic Question ◽  
Red Giants ◽  
Outer Envelope ◽  
Parent Star

When we discuss about MHD effects in planetary nebulae (PNe), there naturally arises a basic question: which magnetic field do we study? One possibility is the ISM magnetic field (e.g. Heiligman 1980), even more if we are concerned with moving PNe (e.g. Soker & Dgani 1997). The next possibility is the internal or stellar magnetic field (Gurzadian 1962). It is important to start this review by quoting Aller (1958): “It has been pointed out by Minkowski and others that the structural appearance of many planetary nebulae strongly suggest the presence of magnetic fields. It seems unlikely that such magnetic fields are produced ab initio in the nebular shell. Rather, they must have existed in the outer envelope of the parent star. Certain red giants stars with magnetic fields may evolve in such a way that the expansion of the shell is largely governed by the presence of such a field. Magnetic effects may actually be more important than gas pressure differentials and radiation pressure in controlling the evolution of a planetary nebula”.

scholarly journals Rayleigh-Teilchen (a < 10-5 cm) im interplanetaren Raum?

1966 ◽  
Vol 21 (7) ◽  
pp. 1116-1122 ◽  
Author(s):  
Hans Elsässer ◽  
Thomas Schmidt
Keyword(s):  
Solar Wind ◽  
Magnetic Fields ◽  
Radiation Pressure ◽  
Interplanetary Space ◽  
Submicron Particles ◽  
Spatial Density ◽  
Zodiacal Light

The question if submicron particles could be present in interplanetary space is discussed in some detail. On the assumption that the polarization of the zodiacal light is due to scattering of sunlight by submicron particles their spatial density is derived (chapter 2). The investigation of the forces exerted on those particles by the radiation pressure of sunlight and by interaction with the particles and magnetic fields of the solar wind shows that the „lifetime“ of submicron particles in interplanetary space is probably less than 103 years (chapter 1 and 3). Therefore it seems doubtful that they can exist in considerable numbers.

scholarly journals THE GENERATION OF STRONG MAGNETIC FIELDS DURING THE FORMATION OF THE FIRST STARS

2010 ◽  
Vol 721 (2) ◽  
pp. L134-L138 ◽  
Author(s):  
Sharanya Sur ◽  
D. R. G. Schleicher ◽  
Robi Banerjee ◽  
Christoph Federrath ◽  
Ralf S. Klessen
Keyword(s):  
Magnetic Fields ◽  
First Stars ◽  
Strong Magnetic Fields

scholarly journals Simulating diverse instabilities of dust in magnetized gas

2020 ◽  
Vol 496 (2) ◽  
pp. 2123-2154 ◽  
Author(s):  
Philip F Hopkins ◽  
Jonathan Squire ◽  
Darryl Seligman
Keyword(s):  
Magnetic Fields ◽  
Radiation Pressure ◽  
Homogeneous Medium ◽  
Density Fluctuations ◽  
Charged Dust ◽  
Magnetic Fluctuations ◽  
Velocity Fluctuations ◽  
Drag Forces ◽  
Dust Plasma ◽  
External Acceleration

ABSTRACT Recently, Squire & Hopkins showed that charged dust grains moving through magnetized gas under the influence of a uniform external force (such as radiation pressure or gravity) are subject to a spectrum of instabilities. Qualitatively distinct instability families are associated with different Alfvén or magnetosonic waves and drift or gyro motion. We present a suite of simulations exploring these instabilities, for grains in a homogeneous medium subject to an external acceleration. We vary parameters such as the ratio of Lorentz-to-drag forces on dust, plasma β, size scale, and acceleration. All regimes studied drive turbulent motions and dust-to-gas fluctuations in the saturated state, rapidly amplify magnetic fields into equipartition with velocity fluctuations, and produce instabilities that persist indefinitely (despite random grain motions). Different parameters produce diverse morphologies and qualitatively different features in dust, but the saturated gas state can be broadly characterized as anisotropic magnetosonic or Alfvénic turbulence. Quasi-linear theory can qualitatively predict the gas turbulent properties. Turbulence grows from small to large scales, and larger scale modes usually drive more vigorous gas turbulence, but dust velocity and density fluctuations are more complicated. In many regimes, dust forms structures (clumps, filaments, sheets) that reach extreme overdensities (up to ≫109 times mean), and exhibit substantial substructure even in nearly incompressible gas. These can be even more prominent at lower dust-to-gas ratios. In other regimes, dust self-excites scattering via magnetic fluctuations that isotropize and amplify dust velocities, producing fast, diffusive dust motions.

scholarly journals Magnetic fields in the formation of the first stars – I. Theory versus simulation

2020 ◽  
Vol 496 (4) ◽  
pp. 5528-5551
Author(s):  
Christopher F McKee ◽  
Athena Stacy ◽  
Pak Shing Li
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Adaptive Mesh Refinement ◽  
Flux Ratio ◽  
Small Scale ◽  
Constant Density ◽  
Analytical Treatment ◽  
First Stars ◽  
Numerical Viscosity ◽  
Grid Based

ABSTRACT While magnetic fields are important in contemporary star formation, their role in primordial star formation is unknown. Magnetic fields of the order of 10−16 G are produced by the Biermann battery due to the curved shocks and turbulence associated with the infall of gas into the dark matter minihaloes that are the sites of formation of the first stars. These fields are rapidly amplified by a small-scale dynamo until they saturate at or near equipartition with the turbulence in the central region of the gas. Analytical results are given for the outcome of the dynamo, including the effect of compression in the collapsing gas. The mass-to-flux ratio in this gas is two to three times the critical value, comparable to that in contemporary star formation. Predictions of the outcomes of simulations using smooth particle hydrodynamics (SPH) and grid-based adaptive mesh refinement are given. Because the numerical viscosity and resistivity for the standard resolution of 64 cells per Jeans length are several orders of magnitude greater than the physical values, dynamically significant magnetic fields affect a much smaller fraction of the mass in simulations than in reality. An appendix gives an analytical treatment of free-fall collapse, including that in a constant-density background. Another appendix presents a new method of estimating the numerical viscosity; results are given for both SPH and grid-based codes.

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