scholarly journals Turbulent power distribution in the local interstellar medium

2019 ◽  
Vol 627 ◽  
pp. A112 ◽  
Author(s):  
P. M. W. Kalberla ◽  
U. Haud
Keyword(s):  
Phase Transitions ◽  
Phase Space ◽  
Interstellar Medium ◽  
Power Distribution ◽  
Single Channel ◽  
Power Spectra ◽  
Hierarchical Structures ◽  
Space Distribution ◽  
Neutral Medium ◽  
Highly Correlated

Context. The interstellar medium (ISM) on all scales is full of structures that can be used as tracers of processes that feed turbulence. Aims. We used H I survey data to derive global properties of the angular power distribution of the local ISM. Methods. HI4PI observations on an nside = 1024 HEALPix grid and Gaussian components representing three phases, the cold, warm, and unstable lukewarm neutral medium (CNM, WNM, and LNM), were used for velocities |vLSR|≤ 25 km s−1. For high latitudes |b| > 20° we generated apodized maps. After beam deconvolution we fitted angular power spectra. Results. Power spectra for observed column densities are exceptionally well defined and straight in log-log presentation with 3D power law indices γ ≥−3 for the local gas. For intermediate velocity clouds (IVCs) we derive γ = −2.6 and for high velocity clouds (HVCs) γ = −2.0. Single-phase power distributions for the CNM, LNM, and WNM are highly correlated and shallow with γ ~−2.5 for multipoles l ≤ 100. Excess power from cold filamentary structures is observed at larger multipoles. The steepest single-channel power spectra for the CNM are found at velocities with large CNM and low WNM phase fractions. Conclusions. The phase space distribution in the local ISM is configured by phase transitions and needs to be described with three distinct different phases, being highly correlated but having distributions with different properties. Phase transitions cause locally hierarchical structures in phase space. The CNM is structured on small scales and is restricted in position-velocity space. The LNM as an interface to the WNM envelops the CNM. It extends to larger scales than the CNM and covers a wider range of velocities. Correlations between the phases are self-similar in velocity.

scholarly journals CMB anisotropies and linear matter power spectrum in models with non-thermal neutrinos and primordial magnetic fields

2021 ◽  
Vol 2021 (11) ◽  
pp. 044
Author(s):  
Kerstin E. Kunze
Keyword(s):  
Magnetic Field ◽  
Phase Space ◽  
Thermal Model ◽  
Degrees Of Freedom ◽  
Numerical Solutions ◽  
Power Spectra ◽  
Space Distribution ◽  
Thermal Phase ◽  
Primordial Magnetic Fields ◽  
Stochastic Magnetic Field

Abstract Angular power spectra of temperature anisotropies and polarization of the cosmic microwave background (CMB) as well as the linear matter power spectra are calculated for models with three light neutrinos with non-thermal phase-space distributions in the presence of a primordial stochastic magnetic field. The non-thermal phase-space distribution function is assumed to be the sum of a Fermi-Dirac and a gaussian distribution. It is found that the known effective description of the non-thermal model in terms of a twin thermal model with extra relativistic degrees of freedom can also be extended to models including a stochastic magnetic field. Numerical solutions are obtained for a range of magnetic field parameters.

scholarly journals Halo uncertainties in electron recoil events at direct detection experiments

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Tarak Nath Maity ◽  
Tirtha Sankar Ray ◽  
Sambo Sarkar
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Direct Detection ◽  
Space Distribution ◽  
Semiconductor Detectors ◽  
Detection Rates ◽  
Phase Space Distribution ◽  
Electron Recoil ◽  
Highly Correlated ◽  
The Impact

AbstractThe dark matter direct detection rates are highly correlated with the phase space distribution of dark matter particles in our galactic neighbourhood. In this paper we make a systematic study of the impact of astrophysical uncertainties on electron recoil events at the direct detection experiments with Xenon and semiconductor detectors. We find that within the standard halo model there can be up to $$ \sim 50\%$$ ∼ 50 % deviation from the fiducial choice in the exclusion bounds from these observational uncertainties. For non-standard halo models we report a similar deviation from the fiducial standard halo model when fitted with recent cosmological N-body simulations while even larger deviations are obtained in case of the observational uncertainties.

A one-dimensional self-gravitating stellar gas

1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar
Keyword(s):  
Gravitational Field ◽  
Phase Space ◽  
Motion Picture ◽  
Space Distribution ◽  
Two Dimensional ◽  
One Dimensional ◽  
Phase Space Distribution ◽  
Dimensional Phase Space ◽  
The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

scholarly journals The Joy of Markov Models—Channel Gating and Transport Cycling Made Easy

2021 ◽  
Author(s):  
G. Zifarelli ◽  
P. Zuccolini ◽  
S. Bertelli ◽  
M. Pusch
Keyword(s):  
Single Molecule ◽  
Protein Function ◽  
Markov Models ◽  
Single Channel ◽  
Real Life ◽  
Power Spectra ◽  
K Channel ◽  
Modular Architecture ◽  
Gating Currents ◽  
Discrete State

ABSTRACT The behavior of ion channels and transporters is often modeled using discrete state continuous-time Markov models. Such models are helpful for the interpretation of experimental data and can guide the design of experiments by testing specific predictions. Here, we describe a computational tool that allows us to create Markov models of chosen complexity and to calculate the predictions on a macroscopic scale, as well on a single-molecule scale. The program calculates steady-state properties (current, state probabilities, and cycle frequencies), deterministic macroscopic and stochastic time courses, gating currents, dwell-time histograms, and power spectra of channels and transporters. In addition, a visual simulation mode allows us to follow the time-dependent stochastic behavior of a single channel or transporter. After a basic introduction into the concept of Markov models, real-life examples are discussed, including a model of a simple K+ channel, a voltage-gated sodium channel, a 3-state ligand-gated channel, and an electrogenic uniporter. In this manner, the article has a modular architecture, progressing from basic to more advanced topics. This illustrates how the MarkovEditor program can serve students to explore Markov models at a basic level but is also suited for research scientists to test and develop models on the mechanisms of protein function.

Simulation study of Landau damping near the persisting to arrested transition

2017 ◽  
Vol 83 (4) ◽  
Author(s):  
Alexander J. Klimas ◽  
Adolfo F. Viñas ◽  
Jaime A. Araneda
Keyword(s):  
Phase Space ◽  
Simulation Study ◽  
High Speed ◽  
Space Distribution ◽  
Landau Damping ◽  
Field Mode ◽  
Low Speed ◽  
Phase Space Distribution ◽  
Saturation Stage ◽  
First Time

A one-dimensional electrostatic filtered Vlasov–Poisson simulation study is discussed. The transition from persisting to arrested Landau damping that is produced by increasing the strength of a sinusoidal perturbation on a background Vlasov–Poisson equilibrium is explored. Emphasis is placed on observed features of the electron phase-space distribution when the perturbation strength is near the transition value. A single ubiquitous waveform is found perturbing the space-averaged phase-space distribution at almost any time in all of the simulations; the sole exception is the saturation stage that can occur at the end of the arrested damping scenario. This waveform contains relatively strong, very narrow structures in velocity bracketing $\pm v_{\text{res}}$ – the velocities at which electrons must move to traverse the dominant field mode wavelength in one of its oscillation periods – and propagating with $\pm v_{\text{res}}$ respectively. Local streams of electrons are found in these structures crossing the resonant velocities from low speed to high speed during Landau damping and from high speed to low speed during Landau growth. At the arrest time, when the field strength is briefly constant, these streams vanish. It is conjectured that the expected transfer of energy between electrons and field during Landau growth or damping has been visualized for the first time. No evidence is found in the phase-space distribution to support recent well-established discoveries of a second-order phase transition in the electric field evolution. While trapping is known to play a role for larger perturbation strengths, it is shown that trapping plays no role at any time in any of the simulations near the transition perturbation strength.

scholarly journals Massive stars shaping the ISM: H I holes and shells in nearby galaxies

1999 ◽  
Vol 193 ◽  
pp. 636-644
Author(s):  
Elias Brinks ◽  
Fabian Walter
Keyword(s):  
Interstellar Medium ◽  
Dwarf Galaxy ◽  
Massive Stars ◽  
Neutral Hydrogen ◽  
Neutral Medium ◽  
Stellar Winds ◽  
X Ray ◽  
Left Behind ◽  
Neutral Gas ◽  
Nearby Galaxies

Neutral hydrogen (H I) is a magnificent tool when studying the structure of the interstellar medium (ISM) as it is relatively easily observable and can be mapped at good spatial and velocity resolution with modern instruments. Moreover, it traces the cool (∼ 100 K) and warm (∼ 5000 K) neutral gas which together make up about 60%, or the bulk, of the ISM. The currently accepted picture is that stellar winds and subsequent supernovae are the origin for the clearly defined holes or bubbles within the more or less smooth neutral medium. The H I can therefore serve indirectly as a tracer of the hot interstellar medium (HIM) left behind after the most massive stars within an OB association have gone off as supernovae. A splendid example is the dwarf galaxy IC 2574 for which we discuss H I, optical and X-ray observations.

scholarly journals Dynamics of The Tranquil Cosmic Web

2014 ◽  
Vol 11 (S308) ◽  
pp. 77-86
Author(s):  
Adi Nusser
Keyword(s):  
Phase Space ◽  
Structure Formation ◽  
Observational Data ◽  
Space Distribution ◽  
Phase Space Distribution ◽  
Redshift Surveys ◽  
Data Analyses ◽  
Galaxy Redshift ◽  
Insight Into

AbstractThe phase space distribution of matter out to ∼ 100 \rm Mpc is probed by two types of observational data: galaxy redshift surveys and peculiar motions of galaxies. Important information on the process of structure formation and deviations from standard gravity have been extracted from the accumulating data. The remarkably simple Zel'dovich approximation is the basis for much of our insight into the dynamics of structure formation and the development of data analyses methods. Progress in the methodology and some recent results is reviewed.

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