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We show that strong magnetic fields can be generated at shock waves associated with formation of galaxies or clusters of galaxies by the Weibel instability, an instability in collisionless plasmas. The estimated strength of the magnetic…

天体物理学 · 物理学 2015-06-24 Yutaka Fujita , Tsunehiko N. Kato

The aim of this thesis is to study the effects on the CMB anisotropy due to primordial magnetic fields and to analyze some favorable scenarios of magnetogenesis constrained by those signatures, including limits on the amplitude of the…

宇宙学与河外天体物理 · 物理学 2019-03-12 Hector J. Hortua

The dynamical evolution of internal space-like dimensions breaks the invariance of the Maxwell's equations under Weyl rescaling of the (conformally flat) four-dimensional metric. Depending upon the number and upon the dynamics of internal…

高能物理 - 唯象学 · 物理学 2009-10-31 Massimo Giovannini

We study the evolution of a stochastic helical magnetic field generated in the early Universe after the electroweak phase transition, using standard magnetohydrodynamics (MHD). We find how the coherence length xi, magnetic energy E_M and…

天体物理学 · 物理学 2017-08-23 Mark Hindmarsh , M. Christensson , A. Brandenburg

Astrophysical objects with negligible resistivity are often threaded by large scale magnetic fields. The generation of these fields is somewhat mysterious, since a magnetic field in a perfectly conducting fluid cannot change the flux…

天体物理学 · 物理学 2007-05-23 E. T. Vishniac , A. Lazarian , J. Cho

Primordial magnetic fields (PMFs) generated in the early Universe may leave observable imprints in the present-day large-scale structure. However, it remains unclear on which spatial scales primordial signatures can survive the nonlinear…

宇宙学与河外天体物理 · 物理学 2026-02-27 Jennifer Schober , Molly Abramson , Sayan Mandal , Salome Mtchedlidze , Tina Kahniashvili

Cold ($T\sim 10^{4} \ \mathrm{K}$) gas is very commonly found in both galactic and cluster halos. There is no clear consensus on its origin. Such gas could be uplifted from the central galaxy by galactic or AGN winds. Alternatively, it…

星系天体物理 · 物理学 2018-07-10 Suoqing Ji , S. Peng Oh , Michael McCourt

Thermal fluctuations of the gauge field lead to monopole formation at the grand unified phase transition in the early Universe, even if the transition is merely a smooth crossover. The dependence of the produced monopole density on various…

高能物理 - 唯象学 · 物理学 2007-05-23 A. Rajantie

Galactic winds probe how stellar feedback regulates the mass and metallicity of galaxies. Observations show that galactic winds are multiphase and magnetised. In the local Universe, the dense phase is traced by emission and absorption…

A gauge invariant and hence physically meaningful definition of magnetic helicity density for random fields is proposed, using the Gauss linking formula, as the density of correlated field line linkages. This definition is applied to the…

天体物理学 · 物理学 2011-02-11 Kandaswamy Subramanian , Axel Brandenburg

In this paper, we revisit in detail the effects of primordial magnetic fields on big bang nucleosynthesis (BBN) including a discussion of the magnetic field geometry and the anomalous magnetic moment. The presence of magnetic fields affects…

天体物理学 · 物理学 2009-12-30 Baolian Cheng , Angela V. Olinto , David N. Schramm , James W. Truran

It is well known that Yang-Mills theory in vacuum has a perturbative instability to spontaneously form a large scale magnetic field (the Savvidy mechanism) and that a constant field is unstable so that a possible ground state has to be…

高能物理 - 唯象学 · 物理学 2009-10-31 Per Elmfors , David Persson

We study a homogeneous and nearly-isotropic Universe permeated by a homogeneous magnetic field. Together with an isotropic fluid, the homogeneous magnetic field, which is the primary source of anisotropy, leads to a plane-symmetric Bianchi…

宇宙学与河外天体物理 · 物理学 2012-01-11 Julian Adamek , Ruth Durrer , Elisa Fenu , Marc Vonlanthen

The role of magnetic fields in the multi-phase interstellar medium (ISM) is explored using magnetohydrodynamic (MHD) simulations that include energy injection by supernova (SN) explosions and allow for dynamo action. Apart from providing…

星系天体物理 · 物理学 2018-10-03 A. Shukurov , C. C. Evirgen , A. Fletcher , P. J. Bushby , F. A. Gent

We show that the decaying magnetohydrodynamic turbulence leads to a more rapid growth of the correlation length of a primordial magnetic field than that caused by the expansion of the Universe. As an example, we consider the magnetic fields…

高能物理 - 唯象学 · 物理学 2016-08-25 D. T. Son

Magnetic fields can drastically change predictions of evolutionary models of massive stars via mass-loss quenching, magnetic braking, and efficient angular momentum transport, which we aim to quantify in this work. We use the MESA software…

The origin of astrophysical magnetic fields observed in galaxies and clusters of galaxies is still unclear. One possibility is that primordial magnetic fields generated in the early Universe provide seeds that grow through compression and…

宇宙学与河外天体物理 · 物理学 2015-06-11 C. Fedeli , L. Moscardini

A symmetry-breaking phase transition in the early universe could have led to the formation of cosmic defects. Because these defects dynamically excite not only scalar and tensor type cosmological perturbations but also vector type ones,…

宇宙学与河外天体物理 · 物理学 2015-06-23 Kouichirou Horiguchi , Kiyotomo Ichiki , Toyokazu Sekiguchi , Naoshi Sugiyama

The evolution of large-scale magnetic fields in disk galaxies is investigated numerically. The gasdynamical simulations in a disk perturbed by spiral or bar potential are incorporated into the kinematic calculations of induction equations…

天体物理学 · 物理学 2007-05-23 K. Otmianowska-Mazur , M. Chiba

We study the generation of large scale primordial magnetic fields by a cosmological phase transition during the radiation dominated era. The setting is a theory of N charged scalar fields coupled to an abelian gauge field, that undergoes a…

天体物理学 · 物理学 2007-05-23 D. Boyanovsky , H. J. de Vega , M. Simionato