Lifshitz tails for alloy type random models in constant magnetic fields: a short review

AbstractAccording to the currently favored picture, relativistic jets in active galactic nuclei (AGN) are launched in the vicinity of the black hole by magnetic fields extracting energy from the spinning black hole or the accretion disk. In the past decades, various models from shocks to magnetic reconnection have been proposed as the energy dissipation mechanism in the jets. This paper presents a short review on how linear polarization observations can be used to constrain the magnetic field structure in the jets of AGN, and how the observations can be used to constrain the various emission models.

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Existence, uniqueness and anisotropic-decay-caused Lifshitz tails of the integrated density of surface states for random surface models

Random Operators and Stochastic Equations ◽

10.1515/rose-2014-0022 ◽

2014 ◽

Vol 22 (4) ◽

Author(s):

Zhongwei Shen

Keyword(s):

Existence And Uniqueness ◽

Surface States ◽

Random Surface ◽

Lifshitz Tails ◽

Impurity Potential ◽

Quantum Regime ◽

Alloy Type ◽

Counting Functions ◽

Surface Models ◽

Classical Quantum

AbstractThe current paper is devoted to the study of existence, uniqueness and Lifshitz tails of the integrated density of surface states (IDSS) for Schrödinger operators with alloy type random surface potentials. We prove the existence and uniqueness of the IDSS for negative energies, which is defined as the thermodynamic limit of the normalized eigenvalue counting functions of localized operators on strips with sections being special cuboids. Under the additional assumption that the single-site impurity potential decays anisotropically, we also prove that the IDSS for negative energies exhibits Lifshitz tails near the bottom of the almost sure spectrum in the following three regimes: the quantum regime, the quantum-classical/classical-quantum regime and the classical regime. We point out that the quantum-classical/classical-quantum regime is new for random surface models.

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Lifshitz tails for alloy-type models in a constant magnetic field

Journal of Physics A Mathematical and Theoretical ◽

10.1088/1751-8113/43/47/474029 ◽

2010 ◽

Vol 43 (47) ◽

pp. 474029 ◽

Cited By ~ 3

Author(s):

Frédéric Klopp

Keyword(s):

Magnetic Field ◽

Constant Magnetic Field ◽

Lifshitz Tails ◽

Alloy Type

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T Tauri stars: magnetic fields and planets

Acta Astrophysica Taurica ◽

10.31059/aat.vol2.iss1.pp9-20 ◽

2021 ◽

Vol 2 (1) ◽

pp. 9-20

Author(s):

Konstantin Grankin

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Large Scale ◽

Magnetic Coupling ◽

Short Review ◽

T Tauri Stars ◽

Young Stars ◽

Doppler Imaging ◽

Hot Jupiters ◽

T Tauri

In this short review we present the results of a study of the large-scale magnetic topologies of T Tauri stars (TTS). A small spectropolarimetric survey of 8 young stars was carried out within two international projects MaPP (Magnetic Protostars and Planets) and MaTYSSE (Magnetic Topologies of Young Stars and the Survival of massive close-in Exoplanets) between 2009 and 2016. For each of our targets we reconstructed the brightness map and the magnetic field topology using Zeeman–Doppler imaging (ZDI). This review contains a brief description of spectropolarimetricdata, the ZDI method, one example of the reconstruction of brightness and magnetic maps, and the properties of magnetic fields of 8 TTS. Our results suggest that AA Tau and LkCa 15 interact with their disks in the propeller mode when their rotation is actively slowed by the star/disk magnetic coupling. We find that magnetic fields of some TTS are variable on a time scale of a few years and are thus intrinsically nonstationary. We report on the detection of a giant exoplanet around V830 Tau and TAP 26. These two new detections suggest that the type II disk migration is efficient at generating newborn hot Jupiters (hJs) around young TTS. The result of our survey is compared to the global picture of magnetic field properties of twenty TTS in the Hertzsprung–Russell diagram. The comparison shows that WTTS exhibit a wider range of field topologies as compared to CTTS, and that magnetic fields of all TTS (CTTS and WTTS as a whole) are mostly poloidal and axisymmetric when they are mostly convective and cooler than 4300 K. This needs to be confirmed with a larger sample of stars.

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Magnetohydrodynamics of an active region

Symposium - International Astronomical Union ◽

10.1017/s0074180900021379 ◽

1968 ◽

Vol 35 ◽

pp. 93-107 ◽

Cited By ~ 2

Author(s):

H. U. Schmidt

Keyword(s):

Electrical Conductivity ◽

Active Region ◽

Magnetic Fields ◽

Magnetic Flux ◽

Intermediate State ◽

Short Review ◽

The Sun ◽

Infinite Conductivity

The dynamics of the magnetic fields which are imbedded into the non-stationary outer layers of the Sun show many facets of interest to observers and theoreticians alike. In a short review I can only deal with a small number of them and occasionally glance at some others. I hate to call these magnetic fields frozen into a matter which is rather in a boiling state, but the electrical conductivity in these layers is high enough to keep matter and magnetic flux together for rather long times, so that we can discuss the most important questions within the framework of magnetohydrodynamics with infinite conductivity. I will first talk mainly about the layers below the photosphere, where the matter controls the motion of the field, secondly about the intermediate state near the photosphere, where matter and field have comparable energy, and finally about the upper layers where the field controls the material motion.

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