scholarly journals Fingerprint of Galactic Loop I on polarized microwave foregrounds

2018 ◽  
Vol 617 ◽  
pp. A90 ◽  
Author(s):  
Hao Liu
Keyword(s):  
Supernova Explosion ◽  
Large Area ◽  
Microwave Background ◽  
Local Bubble ◽  
Galactic Emission ◽  
Primordial Gravitational Waves ◽  
Polarized Emission ◽  
Supernova Explosions ◽  
Foreground Analysis ◽  
The Magnetic Field

Context. Currently, detection of the primordial gravitational waves using the B-mode of cosmic microwave background (CMB) is primarily limited by our knowledge of the polarized microwave foreground emissions. Improvements of the foreground analysis are therefore necessary. As we revealed in an earlier paper, the E-mode and B-mode of the polarized foreground have noticeably different properties, both in morphology and frequency spectrum, suggesting that they arise from different physicalprocesses, and need to be studied separately. Aims. I study the polarized emission from Galactic loops, especially Loop I, and mainly focus on the following questions: Does the polarized loop emission contribute predominantly to the E-mode or B-mode? In which frequency bands and in which sky regions can the polarized loop emission be identified? Methods. Based on a well known result concerning the magnetic field alignment in supernova explosions, a theoretical expectation is established that the loop polarizations should be predominantly E-mode. In particular, the expected polarization angles of Loop I are compared with those from the real microwave band data of WMAP and Planck. Results and conclusions. The comparison between model and data shows remarkable consistency between the data and our expectations at all bands and for a large area of the sky. This result suggests that the polarized emission of Galactic Loop I is a major polarized component in all microwave bands from 23 to 353 GHz, and a considerable part of the polarized foreground likely originates from a local bubble associated with Loop I, instead of the far more distant Galactic emission. This result also provides a possible way to explain the E-to-B excess problem by contribution of the loops. Finally, this work may also provide the first geometrical evidence that the Earth was hit by a supernova explosion.

scholarly journals Local Bubble contribution to the 353-GHz dust polarized emission

2019 ◽  
Vol 631 ◽  
pp. L11 ◽  
Author(s):  
R. Skalidis ◽  
V. Pelgrims
Keyword(s):  
Magnetic Field ◽  
Line Of Sight ◽  
Optical Polarization ◽  
Local Interstellar Medium ◽  
Microwave Background ◽  
Local Bubble ◽  
Submillimeter Wavelengths ◽  
Polarized Emission ◽  
The Magnetic Field ◽  
Robust Evidence

It has not been shown so far whether the diffuse Galactic polarized emission at frequencies relevant for cosmic microwave background (CMB) studies originates from nearby or more distant regions of our Galaxy. This questions previous attempts that have been made to constrain magnetic field models at local and large scales. The scope of this work is to investigate and quantify the contribution of the dusty and magnetized local interstellar medium to the observed emission that is polarized by thermal dust. We used stars as distance candles and probed the line-of-sight submillimeter polarization properties by comparing the emission that is polarized by thermal dust at submillimeter wavelengths and the optical polarization caused by starlight. We provide statistically robust evidence that at high Galactic latitudes (|b| ≥ 60°), the 353 GHz polarized sky as observed by Planck is dominated by a close-by magnetized structure that extends between 200 and 300 pc and coincides with the shell of the Local Bubble. Our result will assist modeling the magnetic field of the Local Bubble and characterizing the CMB Galactic foregrounds.

scholarly journals Magnetorotational Mechanism of Supernova Explosions - Results of 2D Simulations

1998 ◽  
Vol 11 (1) ◽  
pp. 376-376
Author(s):  
S.G. Moiseenko
Keyword(s):  
Magnetic Field ◽  
Equations Of State ◽  
Supernova Explosion ◽  
Neutrino Energy ◽  
Energy Losses ◽  
Rotational Momentum ◽  
Supernova Explosions ◽  
2D Numerical Simulation ◽  
Lagrangian Scheme ◽  
The Magnetic Field

Results of 2D numerical simulation of the magneto rotational mechanism of a supernova explosion are presented. Simulation has been done for the real equations of state and neutrino energy losses have been taken into account. Simulation has been done on the basis of an Implicit Lagrangian scheme on atriangular grid with grid reconstructuring. It is shown that, due to differential rotation of the star, a toroidal component of the magnetic field appears and grows with time. Rotational momentum transfers outwards as the toroidal component grows with time. With the evolution of the process, part of the envelope of the star is ejected. The amounts of the thrown-off mass and energy are estimated. The results of the simulation could be used as a possible explanation for the supernova explosion picture.

scholarly journals Magnetorotational Mechanism: Supernova Explosions and Ejections

2003 ◽  
Vol 214 ◽  
pp. 117-120
Author(s):  
N. V. Ardeljan ◽  
G. S. Bisnovatyi-Kogan ◽  
S. G. Moiseenko
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Numerical Scheme ◽  
Supernova Explosion ◽  
Triangular Grid ◽  
Different Types ◽  
Protostellar Cloud ◽  
Supernova Explosions ◽  
Field Formation ◽  
The Magnetic Field

We made simulations of the collapse of the rotating protostellar cloud. Differential rotation leads to the amplification of the toroidal component of the magnetic field and subsequent ejection of the matter due to the magnetorotational mechanism.Our results show that at different initial configurations of the magnetic field formation of qualitatively different types of explosion takes place. Magnetic field of the dipole type produces a jet-like explosion. Quadrupole-like magnetic field produces supernova explosion whith ejection presumably near equatorial plane. Quantitative estimations of the ejected mass and energy are given.We have done simulation of the collapse of the white dwarf and formation of a differentially rotating neutron star. After the collapse stage the rotating neutron star was formed. The rotation of the neutron star is strongly differential. The presence of the magnetic field (even the weak one) could produce magnetorotational supernova explosion.For the simulations we have used 2D numerical scheme, based on the specially developed numerical method (conservative, implicit, triangular grid, Lagrangian, grid reconstruction).

scholarly journals Dust polarization modelling at large scale over the northern Galactic cap using EBHIS and Planck data

2020 ◽  
Vol 640 ◽  
pp. A100 ◽  
Author(s):  
Debabrata Adak ◽  
Tuhin Ghosh ◽  
Francois Boulanger ◽  
Urmas Haud ◽  
Peter Kalberla ◽  
...  
Keyword(s):  
Column Density ◽  
Large Scale ◽  
Thermal Emission ◽  
Dust Emission ◽  
Primary Source ◽  
Microwave Background ◽  
Density Region ◽  
Modelling Framework ◽  
Galactic Emission ◽  
Primordial Gravitational Waves

The primary source of systematic uncertainty in the quest for the B-mode polarization of the Cosmic Microwave Background (CMB) introduced by primordial gravitational waves is polarized thermal emission from Galactic dust. Therefore, accurate characterization and separation of the polarized thermal dust emission is an essential step in distinguishing such a faint CMB B-mode signal. We provide a modelling framework to simulate polarized thermal dust emission based on the model described in Ghosh et al. (2017, A&A, 601, A71), making use of both the Planck dust and Effelsberg-Bonn HI surveys over the northern Galactic cap. Our seven-parameter dust model, incorporating both HI gas in three different column density templates as a proxy for spatially variable dust intensity and a phenomenological model of Galactic magnetic field, is able to reproduce both one- and two-point statistics of the observed dust polarization maps seen by Planck at 353 GHz over a selected low-column density region in the northern Galactic cap. This work has important applications in assessing the accuracy of component separation methods and in quantifying the confidence level of separating polarized Galactic emission and the CMB B-mode signal, as is needed for ongoing and future CMB missions.

scholarly journals Modeling the magnetized Local Bubble from dust data

2020 ◽  
Vol 636 ◽  
pp. A17 ◽  
Author(s):  
V. Pelgrims ◽  
K. Ferrière ◽  
F. Boulanger ◽  
R. Lallement ◽  
L. Montier
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Galactic Magnetic Field ◽  
Local Bubble ◽  
Local Distortion ◽  
Polar Caps ◽  
Inner Surface ◽  
Polarized Emission ◽  
Magnetic Field Model ◽  
Supernova Explosions

The Sun is embedded in the so-called Local Bubble (LB) – a cavity of hot plasma created by supernova explosions and surrounded by a shell of cold, dusty gas. Knowing the local distortion of the Galactic magnetic field associated with the LB is critical for the modeling of interstellar polarization data at high Galactic latitudes. In this his paper, we relate the structure of the Galactic magnetic field on the LB scale to three-dimensional (3D) maps of the local interstellar medium (ISM). First, we extracted the geometry of the LB shell, its inner surface, in particular from 3D dust extinction maps of the local ISM. We expanded the shell inner surface in spherical harmonics, up to a variable maximum multipole degree, which enabled us to control the level of complexity for the modeled surface. Next, we applied an analytical model for the ordered magnetic field in the shell to the modeled shell surface. This magnetic field model was successfully fitted to the Planck 353 GHz dust polarized emission maps over the Galactic polar caps. For each polar cap, the direction of the mean magnetic field derived from dust polarization (together with the prior that the field points toward longitude 90° ± 90°) is found to be consistent with the Faraday spectra of the nearby diffuse synchrotron emission. Our work presents a new approach to modeling the local structure of the Galactic magnetic field. We expect our methodology and our results to be useful both in modeling the local ISM as traced by its different components and in modeling the dust polarized emission, which is a long-awaited input for studies of the polarized foregrounds for cosmic microwave background.

scholarly journals Interpolation of externally-caused magnetic fields over large sparse arrays using Spherical Elementary Current Systems

2010 ◽  
Vol 28 (9) ◽  
pp. 1795-1805 ◽  
Author(s):  
S. A. McLay ◽  
C. D. Beggan
Keyword(s):  
Magnetic Field ◽  
External Field ◽  
Current System ◽  
Electrical Current ◽  
Ionospheric Currents ◽  
Large Area ◽  
Physically Based ◽  
Subsurface Current ◽  
Current Systems ◽  
The Magnetic Field

Abstract. A physically-based technique for interpolating external magnetic field disturbances across large spatial areas can be achieved with the Spherical Elementary Current System (SECS) method using data from ground-based magnetic observatories. The SECS method represents complex electrical current systems as a simple set of equivalent currents placed at a specific height in the ionosphere. The magnetic field recorded at observatories can be used to invert for the electrical currents, which can subsequently be employed to interpolate or extrapolate the magnetic field across a large area. We show that, in addition to the ionospheric currents, inverting for induced subsurface current systems can result in strong improvements to the estimate of the interpolated magnetic field. We investigate the application of the SECS method at mid- to high geomagnetic latitudes using a series of observatory networks to test the performance of the external field interpolation over large distances. We demonstrate that relatively few observatories are required to produce an estimate that is better than either assuming no external field change or interpolation using latitudinal weighting of data from two other observatories.

Influence of Permanent Magnets Installation Approach on the Torque of а Magneto-Rheological Disk Brake

2021 ◽  
Vol 105 ◽  
pp. 184-193
Author(s):  
Ilya Aleksandrovich Frolov ◽  
Andrei Aleksandrovich Vorotnikov ◽  
Semyon Viktorovich Bushuev ◽  
Elena Alekseevna Melnichenko ◽  
Yuri Viktorovich Poduraev
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Materials ◽  
Permanent Magnets ◽  
Magnetorheological Fluid ◽  
Simulation Modelling ◽  
Disc Brake ◽  
Large Area ◽  
Braking Torque ◽  
The Magnetic Field

Magnetorheological braking devices function due to the organization of domain structures between liquid and solid magnetic materials under the action of an electromagnetic or magnetic field. The disc is most widely used as a rotating braking element that made of a solid magnetic material due to the large area of contact with a magnetorheological fluid. Many factors affect the braking characteristics of the magnetorheological disc brake. Specifically, the value of the magnetic field and how the field is distributed across the work element is significantly affected at the braking torque. There are different ways to generate a magnetic field. In this study, the method of installation of permanent magnets into the construction, allowing to increase the braking torque of the magnetorheological disc brake is proposed. Simulation modelling showing the distribution of the magnetic field across the disk depending on the installation of permanent magnets with different pole orientations were carried out. The model takes into account the possibility of increasing the gap between solid magnetic materials of the structure, inside them which the magnetorheological fluid is placed. Comparative estimation of the distribution of the magnetic fields depending on the chosen method of installation of permanent magnets with different orientations of their poles is carried out. Further research is planned to focus on a comparative assessment of the distribution of magnetic fields depending on the selected material of the braking chamber.

scholarly journals The Magnetic Field Near the Local Bubble

1997 ◽  
Vol 166 ◽  
pp. 227-238
Author(s):  
Carl Heiles
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Zeeman Splitting ◽  
Relativistic Electrons ◽  
Local Bubble ◽  
Scale Field ◽  
Large Scale Field ◽  
Field Lines ◽  
Hi Shells ◽  
The Magnetic Field

AbstractThere are almost no direct observational indicators of the magnetic field inside the local bubble. Just outside the bubble, the best tracers are stellar polarization and HI Zeeman splitting. These show that the local field does not follow the large-scale Galactic field. Here we discuss whether the deformation of the large-scale field by the local HI shells is consistent with the observations. We concentrate on the Loop 1 region, and find that the field lines are well-explained by this idea; in addition, the bright radio filaments of Radio Loop 1 delineate particular field lines that are “lit up” by an excess of relativistic electrons.

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