scholarly journals 4.12. A molecular cloud interacting by the vertical filaments of the Galactic center radio arc

1998 ◽  
Vol 184 ◽  
pp. 191-192
Author(s):  
Tomoharu Oka ◽  
Tetsuo Hasegawa ◽  
Fumio Sato ◽  
Masato Tsuboi ◽  
Atsushi Miyazaki
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Molecular Cloud ◽  
Galactic Center ◽  
Relativistic Particle ◽  
Particle Source ◽  
Field Lines

Surely the most striking radio feature in the Galactic center may be a sheaf of straight vertical filaments (VFs, e.g., Yusef-Zadeh, Morris, & Chance 1984) of the radio arc. The VFs are believed to be the manifestations of strong magnetic field lines (≥1mG) which have been illuminated by some local relativistic particle source.

scholarly journals MHD Models of Galactic Center Lobes, Shells, and Filaments

1990 ◽  
Vol 140 ◽  
pp. 379-380
Author(s):  
Kazunari Shibata ◽  
Ryoji Matsumoto
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Galactic Center ◽  
Transient State ◽  
Rotating Disk ◽  
Quasi Equilibrium ◽  
Two Dimensional ◽  
The Galaxy ◽  
Field Lines

Magnetohydrodynamic (MHD) mechanisms producing radio lobes, shells, and filaments in the Galactic center as well as in the gas disk of the Galaxy are studied by using two-dimensional MHD code: (a) the explosion in a magnetized disk, (b) the interaction of a rotating disk with vertical fields, and (c) the nonlinear Parker instability in toroidal magnetic fields in a disk. In all cases, dense shells or filaments are created along magnetic field lines in a transient state, in contrast to the quasi-equilibrium filaments perpendicular to magnetic fields.

scholarly journals The Nature of the Galactic Center Arc

1996 ◽  
Vol 169 ◽  
pp. 263-269 ◽  
Author(s):  
E. Serabyn
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Galactic Center ◽  
Magnetic Energy ◽  
Linear Structure ◽  
High Energy ◽  
Molecular Gas ◽  
Synchrotron Emission ◽  
Interferometric Imaging ◽  
Relativistic Particles

Ever since the Galactic Center Arc was resolved into its component filaments a decade ago, it has been clear that its linear structure arises from the influence of a strong magnetic field. However, the origin and nature of the contributory phenomena have remained elusive. Since what is seen is synchrotron emission from relativistic particles, of prime interest is a knowledge of the acceleration mechanism involved. Interferometric imaging of the molecular gas in the vicinity of the Arc has now provided a tantalizing clue to the Arc's origin: molecular clumps coinciding with the endpoints of a number of the Arc's filaments point to these clumps as the source of the relativistic particles. This suggests that as dense molecular clumps course through the ambient magnetic field at the Galactic Center, magnetic energy is liberated in their leading layers via field reconnection, precipitating rapid acceleration of free charges to high energy.

scholarly journals Filamentary Structures Near the Galactic Center

1989 ◽  
Vol 136 ◽  
pp. 243-263 ◽  
Author(s):  
F. Yusef-Zadeh
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Galactic Center ◽  
Galactic Plane ◽  
Galactic Rotation ◽  
Physical Interaction ◽  
Magnetic Structures ◽  
The Galaxy ◽  
Field Lines ◽  
The Magnetic Field

Recent studies of the Galactic center environment have revealed a wealth of new thermal and nonthermal features with unusual characteristics. A system of nonthermal filamentary structures tracing magnetic field lines are found to extend over 200pc in the direction perpendicular to the Galactic plane. Ionized structures, like nonthermal features, appear filamentary and show forbidden velocity fields in the sense of Galactic rotation and large line widths. Faraday rotation characteristics and the flat spectral index distributions of the nonthermal filaments suggest a mixture of thermal and nonthermal gas. Furthermore, the relative spatial distributions of the magnetic structures with respect to those of the ionized and molecular gas suggest a physical interaction between these two systems. In spite of numerous questions concerning the origin of the large-scale organized magnetic structures, the mechanism by which particles are accelerated to relativistic energies, and the source or sources of heating the dust and gas, recent studies have been able to distinguish the inner 200pc of the nucleus from the disk of the Galaxy in at least two more respects: (1) the recognition that the magnetic field has a large-scale structure and is strong, uniform and dynamically important; and (2) the physics of interstellar matter may be dominated by the poloidal component of the magnetic field.

scholarly journals The Strong Magnetic Field Galactic Center-AGN-Quasar Model

1989 ◽  
Vol 136 ◽  
pp. 335-340 ◽  
Author(s):  
Howard D. Greyber
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Galactic Center ◽  
Galactic Disk ◽  
Galactic Nuclei ◽  
Current Loop ◽  
Toroidal Plasma ◽  
Extended Radio ◽  
The Galaxy ◽  
Magnetic Field Model

The energy storage and dynamics at the center of galaxies is explained using a new construct, the gravitationally bound current loop (GBCL), produced when the galaxy formed under gravitational collapse. Thin toroidal plasma around the slender intense relativistic current loop is bound to it by the Maxwell “frozen-field” condition, and also binds gravitationally to the central object (presumably a black hole). The Strong Magnetic Field model (SMF) explains directly the Milky Way (MW) galactic center radio observations of a vertical magnetic field perpendicular to the galactic disk and the extended radio arcs, as well as the production of successive radio blobs ejected from the compact cores of active galactic nuclei (AGN) or quasars.

scholarly journals 8.6. Magnetic reconnection as the origin of superhot plasmas in the Galactic center

1998 ◽  
Vol 184 ◽  
pp. 355-356
Author(s):  
T. Yokoyama ◽  
S. Tanuma ◽  
T. Kudoh ◽  
K. Shibata
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Time Scale ◽  
Galactic Center ◽  
Galactic Disk ◽  
Magnetic Loop ◽  
Occurrence Rate ◽  
Galactic Rotation ◽  
X Ray ◽  
Field Lines

Recent X-ray astronomy satellite (e.g., Ginga, ASCA) has revealed that the center of our Galaxy is filled with a large amount of very hot plasmas (a few − 10 keV) on a scale of 100 pc, which are referred to as superhot plasmas. These plasmas are similar to the Galactic Ridge X-ray Emission (GRXE; cf Tanuma et al. 1997), but with larger gas pressure, and their formation mechanism has been a big puzzle. Here we propose a new model, magnetic reconnection model (Fig. 1), to explain the heating as well as the confinement of the Galactic center superhot plasmas, by performing MHD numerical simulations of magnetic reconnection in the situation suitable for the Galactic center. In our model, the magnetic field is amplified by the rotation of the Galactic gas disk (Fig. 2), and inflate from the disk to outside by the Parker instability. The inflating magnetic loop collides with ambient field lines, thus inducing the magnetic reconnection (the same process applied to the solar corona is shown in Yokoyama and Shibata 1995). In this model, energy release per single reconnection event is ΔE ≈ emVrec ≈ 2 × 1051 erg where em = P/β is the energy density of toroidal magnetic field, Vrec = λ2δ is the volume of the event, λ ≈ 60pc is the most unstable wavelength of the Parker instability, and δ ≈ 3pc is the thickness of the Galactic disk. The occurrence rate of this event is f ≈ N/Δτdep ≈ (3 × 104 yr)−1 where N = Vdisk/Vrec is the number of current sheets in the disk, Vdisk is the volume of the disk, and Δτdep is the time scale of energy deposit which is comparable with the time scale of the Galactic rotation. Then, the heating rate is h = fΔE = 2 × 1039 erg s−1 = 100L2–10keV.

scholarly journals Runaway electron flows in magnetized coaxial gas diodes

2021 ◽  
Vol 2064 (1) ◽  
pp. 012006
Author(s):  
G A Mesyats ◽  
K A Sharypov ◽  
V G Shpak ◽  
S A Shunailov ◽  
M I Yalandin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Strong Magnetic Field ◽  
Current Density ◽  
Runaway Electron ◽  
Electron Flow ◽  
Transverse Size ◽  
Longitudinal Field ◽  
Field Lines ◽  
A Current

Abstract This paper presents the experimental results on applying a strong magnetic field (B) to increase the uniformity and density of a picosecond runaway electron flow (RAEF) formed in an air coaxial diode with a tubular cathode. A uniform longitudinal field Bz allows to confine RAEF similarly to the electron beam in a magnetically insulated coaxial vacuum diode. Dependence of the spatial discreteness of RAEF emission and the transverse size of the emitting plasma regions on Bz has been demonstrated. For the cathode diameter of 8 mm, a current density was significantly increased from 40 A/cm2 (at Bz = const) to 100 A/cm2 by applying B-field with converging field lines. In the region of B maximum (5 T) the RAEF diameter was squeezed by ≈ 4 times.

Liquid-metal flow in a backward elbow in the plane of a strong magnetic field

1991 ◽  
Vol 227 ◽  
pp. 273-292 ◽  
Author(s):  
T. J. Moon ◽  
T. Q. Hua ◽  
J. S. Walker
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Strong Magnetic Field ◽  
Metal Flow ◽  
Interior Layer ◽  
Viscous Effects ◽  
Liquid Metal Flow ◽  
Constant Area ◽  
Field Lines ◽  
The Magnetic Field

This paper treats a liquid-metal flow through a sharp elbow connecting two constant-area, rectangular ducts with thin metal walls. There is a uniform, strong magnetic field in the plane of the ducts’ centrelines, and the velocity component normal to the magnetic field is in opposite directions upstream and downstream of the elbow. The magnetic field is sufficiently strong that inertial effects are negligible everywhere and viscous effects are confined to boundary layers and to an interior layer lying along the magnetic field lines through the inside corner of the elbow. The interior layer involves large velocities parallel to the magnetic field and carries roughly half of the flow between the upstream and downstream ducts for the case considered.

scholarly journals Cloud–cloud collision in the Galactic Center Arc

2020 ◽  
Author(s):  
Masato Tsuboi ◽  
Yoshimi Kitamura ◽  
Kenta Uehara ◽  
Ryosuke Miyawaki ◽  
Takahiro Tsutsumi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Emission Line ◽  
Molecular Cloud ◽  
Galactic Center ◽  
Compact Objects ◽  
Emission Lines ◽  
Common Mechanism ◽  
Poloidal Magnetic Field ◽  
Sagittarius A ◽  
Vertical Part

Abstract We performed a search of cloud–cloud collision (CCC) sites in the Sagittarius A molecular cloud (SgrAMC) based on the survey observations using the Nobeyama 45 m telescope in the C32S J = 1–0 and SiO v = 0 J = 2–1 emission lines. We found candidates abundant in shocked molecular gas in the Galactic Center Arc (GCA). One of them, M0.014−0.054, is located in the mapping area of our previous ALMA mosaic observation. We explored the structure and kinematics of M0.014−0.054 in the C32S J = 2–1, C34S J = 2–1, SiO v = 0 J = 2–1, H13CO+J = 1–0, and SO N, J = 2, 2–1, 1 emission lines and fainter emission lines. M0.014−0.054 is likely formed by the CCC between the vertical molecular filaments (the “vertical part,” or VP) of the GCA, and other molecular filaments along Galactic longitude. The bridging features between these colliding filaments on the PV diagram are found, which are the characteristics expected in CCC sites. We also found continuum compact objects in M0.014−0.054, which have no counterpart in the H42α recombination line. They are detected in the SO emission line, and would be “hot molecular cores” (HMCs). Because the local thermodynamic equilibrium mass of one HMC is larger than the virial mass, it is bound gravitationally. This is also detected in the CCS emission line. The embedded star would be too young to ionize the surrounding molecular cloud. The VP is traced by a poloidal magnetic field. Because the strength of the magnetic field is estimated to be ∼mgauss using the Chandrasekhar–Fermi method, the VP is supported against fragmentation. The star formation in the HMC of M0.014−0.054 is likely induced by the CCC between the stable filaments, which may be a common mechanism in the SgrAMC.

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