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The majority of astrophysics involves the study of spiral galaxies, and stars and planets within them, but how spiral arms in galaxies form and evolve is still a fundamental problem. Major progress in this field was made primarily in the…

Astrophysics of Galaxies · Physics 2015-06-22 Clare Dobbs , Junichi Baba

The dynamical nature and formation mechanism(s) of galactic spiral arms remain long-standing problems in astrophysics. Most theoretical work is based on analytic calculations or idealised simulations, which has yielded several theories of…

Computational heliophysics has shed light on the fundamental physical processes inside the Sun, such as the differential rotation, meridional circulation, and dynamo-generation of magnetic fields. However, despite the substantial advances,…

Solar and Stellar Astrophysics · Physics 2023-01-25 A. G. Kosovichev , G. Guerrero , A. M. Stejko , V. V. Pipin , A. V. Getling

Using a population of large-scale filaments extracted from an AREPO simulation of a Milky Way-like galaxy, we seek to understand the extent to which observed large-scale filament properties (with lengths $\gtrsim 100$ pc) can be explained…

Astrophysics of Galaxies · Physics 2020-01-01 Catherine Zucker , Rowan Smith , Alyssa Goodman

We construct a magnetic helicity conserving dynamo theory which incorporates a calculated magnetic helicity current. In this model the fluid helicity plays a small role in large scale magnetic field generation. Instead, the dynamo process…

Astrophysics · Physics 2009-10-31 Ethan T. Vishniac , Jungyeon Cho

We perform three-dimensional numerical simulations of stellar winds of early-M dwarf stars. Our simulations incorporate observationally reconstructed large-scale surface magnetic maps, suggesting that the complexity of the magnetic field…

Solar and Stellar Astrophysics · Physics 2015-06-18 A. A. Vidotto , M. Jardine , J. Morin , J. F. Donati , M. Opher , T. I. Gombosi

Theories of stellar spiral arms in disk galaxies can be grouped into two classes based on the longevity of a spiral arm. Although the quasi-stationary density wave theory supposes that spirals are rigidly-rotating, long-lived patterns, the…

Astrophysics of Galaxies · Physics 2015-07-15 Junichi Baba , Kana Morokuma-Matsui , Fumi Egusa

(Abridged) We use new multi-wavelength radio observations, made with the VLA and Effelsberg telescopes, to study the magnetic field of the nearby galaxy M51 on scales from $200\pc$ to several $\kpc$. Interferometric and single dish data are…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 A. Fletcher , R. Beck , A. Shukurov , E. M. Berkhuijsen , C. Horellou

The main observational results from radio continuum and polarization observations about the magnetic field strength and large-scale pattern for face-on and edge-on spiral galaxies are summarized and compared within our sample of galaxies of…

Astrophysics · Physics 2009-05-07 Marita Krause

An analytical model predicting the growth rates, the absolute growth times and the saturation values of the magnetic field strength within galactic haloes is presented. The analytical results are compared to cosmological MHD simulations of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Alexander M. Beck , Harald Lesch , Klaus Dolag , Hanna Kotarba , Annette Geng , Federico A. Stasyszyn

Context. Magnetic fields are key to understand galaxy evolution, regulating stellar feedback and star formation in galaxies. Aims. We probe the origin of magnetic fields in late-type galaxies, measuring magnetic field strengths, exploring…

Despite their ubiquity, the origin of cosmic magnetic fields remains unknown. Various mechanisms have been proposed for their existence including primordial fields generated by inflation, or amplification and injection by compact…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-23 Harley Katz , Sergio Martin-Alvarez , Julien Devriendt , Adrianne Slyz , Taysun Kimm

[Abridged abstract:] Stellar activity data provide evidence of activity wave branches propagating polewards rather than equatorwards (the solar case). Stellar dynamo theory allows polewards propagating dynamo waves for certain governing…

Solar and Stellar Astrophysics · Physics 2015-05-28 D. Moss , D. Sokoloff , A. F. Lanza

The arm structure of the Milky Way remains somewhat of an unknown, with observational studies hindered by our location within the Galactic disc. In the work presented here we use smoothed particle hydrodynamics (SPH) and radiative transfer…

Astrophysics of Galaxies · Physics 2015-06-24 Alex R. Pettitt , Clare L. Dobbs , David M. Acreman , Matthew R. Bate

We aim to use statistical analysis of a large number of various galaxies to probe, model, and understand relations between different galaxy properties and magnetic fields. We have compiled a sample of 55 galaxies including low-mass dwarf…

Astrophysics of Galaxies · Physics 2017-07-19 Krzysztof T. Chyzy , Sarrrvesh S. Sridhar , Wojciech Jurusik

Recent rotation measure observations of a dozen or so galaxy clusters have revealed a surprisingly large amount of magnetic fields, whose estimated energy and flux are, on average, $\sim 10^{58}$ ergs and $\sim 10^{41}$ G cm$^2$,…

Astrophysics · Physics 2007-05-23 Stirling A. Colgate , Hui Li

We quantify the effects of magnetic fields, cosmic rays and gas pressure on the rotational velocity of HI gas in the Milky Way, at galactic distances between Rsun and 2Rsun. The magnetic field is modelled by two components; a mainly…

Astrophysics of Galaxies · Physics 2015-06-15 F. J. Sanchez-Salcedo , A. Santillan

Using 3D global hydro simulations coupled with radiative transfer calculations, we study the appearance of density waves induced by giant planets in direct imaging observations at near infrared wavelengths. We find that a 6 MJ planet in a…

Earth and Planetary Astrophysics · Physics 2015-08-19 Ruobing Dong , Zhaohuan Zhu , Roman Rafikov , James Stone

We compare various models and approximations for non-linear mean-field dynamos in disc galaxies to assess their applicability and accuracy, and thus to suggest a set of simple solutions suitable to model the large-scale galactic magnetic…

Astrophysics of Galaxies · Physics 2015-06-19 Luke Chamandy , Anvar Shukurov , Kandaswamy Subramanian , Katherine Stoker

We model the effects of the spiral arms of the Milky Way on the disk stellar kinematics in the Gaia observable space. We also estimate the Gaia capabilities of detecting the predicted signatures. We use both controlled orbital integrations…

Astrophysics of Galaxies · Physics 2016-04-20 T. Antoja , S. Roca-Fabrega , J. de Bruijne , T. Prusti