scholarly journals Magnetic Reconnection as the Origin of Galactic Ridge X-Ray Emission

1998 ◽  
Vol 188 ◽  
pp. 269-270 ◽  
Author(s):  
S. Tanuma ◽  
T. Yokoyama ◽  
T. Kudoh ◽  
K. Shibata ◽  
R. Matsumoto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Galactic Plane ◽  
Thermal Emission ◽  
Mhd Equations ◽  
Magnetic Islands ◽  
Cool Component ◽  
X Ray ◽  
Hot Plasma ◽  
Helical Tubes

We present a scenario for the origin of the hot plasma in our Galaxy, as a model of a strong X-ray emission (LX(2 – 10keV) ~ 1038 erg s−1), called Galactic Ridge X-ray Emission (GRXE), which has been observed near the Galactic plane. GRXE is thermal emission from hot component (~ 7 keV) and cool component (~ 0.8 keV). Observations suggest that the hot component is diffuse, and is not escaping away freely. Both what heats the hot component and what confines it in the Galactic ridge are still remained puzzling, while the cool component is believed to be made by supernovae. We propose a new scenario: the hot component of GRXE plasma is heated by magnetic reconnection, and confined in the helical magnetic field produced by magnetic reconnection or in the current sheet and magnetic field. We solved also the 2-dimensional magnetohydrodynamic (MHD) equations numerically to study how the magnetic reconnection creates hot plasmas and magnetic islands (helical tubes), and how the magnetic islands confine the hot plasmas in Galaxy. We conclude that the magnetic reconnection is able to heat up the cool component to hot component of GRXE plasma if the magnetic field is localized into intense flux tube with Blocal ~ 30 μG (the volume filling factor of f ~ 0.1).

scholarly journals MHD Numerical Simulations of Magnetic Reconnection Associated with Emerging Flux

1993 ◽  
Vol 141 ◽  
pp. 500-503
Author(s):  
K. Shibata ◽  
S. Nozawa ◽  
R. Matsumoto
Keyword(s):  
Magnetic Field ◽  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Coronal Magnetic Field ◽  
Two Dimensional ◽  
Magnetic Islands ◽  
X Ray ◽  
Hot Plasma ◽  
Mass Ejection ◽  
Coronal Field

AbstractTwo-dimensional (2D) magnetohydrodynamic (MHD) numerical simulations have been performed to study magnetic reconnection between emerging flux and the overlying coronal magnetic field, taking into account of gravity. It is found that (1) reconnection starts when most of chromospheric mass in the current sheet between the emerging flux and the coronal field has drained down along the loop because of gravity, (2) multiple magnetic islands, which confine cool, dense chromospheric plasma, are created in the sheet; the islands coalesce dynamically and are ejected along the sheet, together with the ambient hot plasma, at Alfven speed. The coexistence of hot and cool plasmas in the mass ejection (jet) associated with the reconnection seems to explain those X-ray jets observed by Yohkoh, which are identified with Hα surges.

scholarly journals Evolution of MAXI J1631–479 during the January 2019 outburst observed by INTEGRAL/IBIS

2020 ◽  
Vol 492 (3) ◽  
pp. 3657-3661 ◽  
Author(s):  
M Fiocchi ◽  
F Onori ◽  
A Bazzano ◽  
A J Bird ◽  
A Bodaghee ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Thermal Emission ◽  
Spectral Characteristics ◽  
Monitoring Program ◽  
High Energy ◽  
Thermal Electron ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Black Hole Candidate ◽  
Decay Times

ABSTRACT We report on a recent bright outburst from the new X-ray binary transient MAXI J1631–479, observed in January 2019. In particular, we present the 30–200 keV analysis of spectral transitions observed with INTEGRAL/IBIS during its Galactic plane monitoring program. In the MAXI and BAT monitoring period, we observed two different spectral transitions between the high/soft and low/hard states. The INTEGRAL spectrum from data taken soon before the second transition is best described by a Comptonized thermal component with a temperature of kTe ∼ 30 keV and a high-luminosity value of $L_{2-200\, \mathrm{keV}}\sim 3\times 10^{38}$ erg−1 (assuming a distance of 8 kpc). During the second transition, the source shows a hard, power-law spectrum. The lack of high energy cut-off indicates that the hard X-ray spectrum from MAXI J1631–479 is due to a non-thermal emission. Inverse Compton scattering of soft X-ray photons from a non-thermal or hybrid thermal/non-thermal electron distribution can explain the observed X-ray spectrum although a contribution to the hard X-ray emission from a jet cannot be determined at this stage. The outburst evolution in the hardness-intensity diagram, the spectral characteristics, and the rise and decay times of the outburst are suggesting that this system is a black hole candidate.

scholarly journals X-Ray Flares and Outflows Driven by Magnetic Interaction Between a Protostar and its Surrounding Disk

1997 ◽  
Vol 163 ◽  
pp. 717-718
Author(s):  
Mitsuru Hayashi ◽  
Kazunari Shibata ◽  
Ryoji Matsumoto
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Plasma Temperature ◽  
Magnetic Interaction ◽  
Central Star ◽  
X Ray ◽  
Mhd Simulations ◽  
Flare Loops ◽  
Hot Plasma ◽  
Dipole Magnetic Field

AbstractHere we present a model of hard X-ray flares and hot plasma outflows (optical jets) observed in protostars. Assuming that the dipole magnetic field of a protostar threads the protostellar disk, we carried out 2.5-dimensional magnetohydrodynamic (MHD) simulations of the diskstar interaction. The closed magnetic loops connecting the central star and the disk are twisted by the rotation of the disk. In the presence of resistivity, magnetic reconnection takes place in the current sheet formed inside the expanding loops. Hot, outgoing plasmoid and post flare loops are formed as a result of the reconnection. Numerical results are consistent with the observed plasma temperature (107 – 108K), the length of the flaring loop (1011 – 1012cm), and the speed of optical jets (200 – 400 km s−1 ).

scholarly journals Early neutron star evolution in high-mass X-ray binaries

2020 ◽  
Vol 494 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Wynn C G Ho ◽  
M J P Wijngaarden ◽  
Nils Andersson ◽  
Thomas M Tauris ◽  
F Haberl
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Thermal Emission ◽  
Equilibrium Phase ◽  
High Mass ◽  
X Ray ◽  
Spin Period ◽  
Long Duration ◽  
X Ray Binaries ◽  
The Magnetic Field

ABSTRACT The application of standard accretion theory to observations of X-ray binaries provides valuable insights into neutron star (NS) properties, such as their spin period and magnetic field. However, most studies concentrate on relatively old systems, where the NS is in its late propeller, accretor, or nearly spin equilibrium phase. Here, we use an analytic model from standard accretion theory to illustrate the evolution of high-mass X-ray binaries (HMXBs) early in their life. We show that a young NS is unlikely to be an accretor because of the long duration of ejector and propeller phases. We apply the model to the recently discovered ∼4000 yr old HMXB XMMU J051342.6−672412 and find that the system’s NS, with a tentative spin period of 4.4 s, cannot be in the accretor phase and has a magnetic field B > a few × 1013 G, which is comparable to the magnetic field of many older HMXBs and is much higher than the spin equilibrium inferred value of a few × 1011 G. The observed X-ray luminosity could be the result of thermal emission from a young cooling magnetic NS or a small amount of accretion that can occur in the propeller phase.

scholarly journals The Soft X-ray Background Spectrum from DXS

1997 ◽  
Vol 166 ◽  
pp. 83-90 ◽  
Author(s):  
W.T. Sanders ◽  
R.J. Edgar ◽  
D.A. Liedahl ◽  
J.P. Morgenthaler
Keyword(s):  
Galactic Plane ◽  
Emission Lines ◽  
Background Spectrum ◽  
Local Bubble ◽  
X Ray ◽  
Hot Plasma ◽  
Solar Abundances ◽  
Ionic Emission ◽  
X Ray Background ◽  
Ionization Balance

AbstractThe Diffuse X-ray Spectrometer (DXS) obtained spectra of the low energy X-ray (44 – 83 Å) diffuse background near the galactic plane from galactic longitudes 150° ≲ l ≲ 300° with ≲ 3 Å spectral resolution and ~ 15° angular resolution. Thus, DXS measured X-ray spectra that arise almost entirely from within the Local Bubble. The DXS spectra show emission lines and emission-line blends, indicating that the source of the X-ray emission is thermal – hot plasma in the Local Bubble. The measured spectra are not consistent with those predicted by standard coronal models, either with solar abundances or depleted abundances, over the temperature range 105 – 107 K. The measured spectra are also inconsistent with the predictions of various non-equilibrium models. A nearly acceptable fit to DXS spectra can be achieved using a hybrid model that combines the Raymond & Smith ionization balance calculation with recently calculated (by DAL) ionic emission lines.

scholarly journals Solar wind interaction with the Earth's magnetosphere: the role of reconnection in the presence of a large scale sheared flow

2009 ◽  
Vol 16 (1) ◽  
pp. 1-10 ◽  
Author(s):  
F. Califano ◽  
M. Faganello ◽  
F. Pegoraro ◽  
F. Valentini
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Large Scale ◽  
Initial Conditions ◽  
Magnetic Layer ◽  
Magnetic Islands ◽  
Solar Wind Interaction ◽  
Earth’S Magnetosphere ◽  
Earth's Magnetosphere

Abstract. The Earth's magnetosphere and solar wind environment is a laboratory of excellence for the study of the physics of collisionless magnetic reconnection. At low latitude magnetopause, magnetic reconnection develops as a secondary instability due to the stretching of magnetic field lines advected by large scale Kelvin-Helmholtz vortices. In particular, reconnection takes place in the sheared magnetic layer that forms between adjacent vortices during vortex pairing. The process generates magnetic islands with typical size of the order of the ion inertial length, much smaller than the MHD scale of the vortices and much larger than the electron inertial length. The process of reconnection and island formation sets up spontaneously, without any need for special boundary conditions or initial conditions, and independently of the initial in-plane magnetic field topology, whether homogeneous or sheared.

scholarly journals Hot gas heating via magnetic arms in spiral galaxies

2020 ◽  
Vol 640 ◽  
pp. A109
Author(s):  
M. Weżgowiec ◽  
M. Ehle ◽  
M. Soida ◽  
R.-J. Dettmar ◽  
R. Beck ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Radio Emission ◽  
Magnetic Reconnection ◽  
Spiral Galaxy ◽  
Surrounding Medium ◽  
Spiral Arms ◽  
X Ray ◽  
Hot Gas ◽  
Gas Heating

Context. Reconnection heating has been considered as a potential source of the heating of the interstellar medium. In some galaxies, significant polarised radio emission has been found between the spiral arms. This emission has a form of “magnetic arms” that resembles the spiral structure of the galaxy. Reconnection effects could convert some of the energy of the turbulent magnetic field into the thermal energy of the surrounding medium, leaving more ordered magnetic fields, as is observed in the magnetic arms. Aims. Sensitive radio and X-ray data for the grand-design spiral galaxy M 83 are used for a detailed analysis of the possible interactions of magnetic fields with hot gas, including a search for signatures of gas heating by magnetic reconnection effects. Methods. Magnetic field strengths and energies derived from the radio emission are compared with the parameters of the hot gas calculated from the model fits to sensitive X-ray spectra of the hot gas emission. Results. The available X-ray data allowed us to distinguish two thermal components in the halo of M 83. We found slightly higher average temperatures of the hot gas in the interarm regions, which results in higher energies per particle and is accompanied by a decrease in the energy density of the magnetic fields. Conclusions. The observed differences in the energy budget between the spiral arms and the interarm regions suggest that, similar to the case of another spiral galaxy NGC 6946, we may be observing hints for gas heating by magnetic reconnection effects in the interarm regions. These effects, which act more efficiently on the turbulent component of the magnetic field, are expected to be stronger in the spiral arms. However, with the present data it is only possible to trace them in the interarm regions, where the star formation and the resulting turbulence is low.

scholarly journals Statistics of Radio-X-Ray Emission and Magnetic Fields in the Intergalactic Medium

1990 ◽  
Vol 139 ◽  
pp. 414-415
Author(s):  
Hitoshi Hanami
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Intergalactic Medium ◽  
Relativistic Electrons ◽  
X Ray ◽  
Cooling Flows ◽  
Hot Plasma ◽  
Inverse Compton ◽  
The Magnetic Field

X-ray observations have demonstrated that the intergalactic medium in many clusters (cf. Coma, Perseus) contains a thin, hot plasma that may be produced by the accretion process in the gravitational potential of clusters with radiative cooling; this is usually called “cooling flows” (Fabian, Nulsen, and Canizares 1984; Sarazin 1986). On the other hand, the existence of radio halos in some clusters has been reported (Coma: Jaffe, Perola, and Valentijn 1976; A401: Roland et al. 1981). In addition, many elliptical galaxies in the center of clusters are also strong synchrotron radio sources. These radio emissions provide evidence for large amounts of relativistic electrons associated with the active phenomena in or around these galaxies and clusters. We can estimate the values or limits on the magnetic field in the cluster from the limits on the inverse Compton X-ray emission with the synchrotron radio emission (cf. Jaffe 1980). The intracluster field strength Bo is roughly 1 μG. It has been suggested that the influence of cosmic rays and magnetic fields is important for the properties and dynamics of the intercluster medium (Böhringer and Morfill 1988; Soker and Sarazin 1989). If cooling flows are real, this inward flow can impede the escape of the cosmic rays from the central galaxies in clusters and enhance the magnetic field. The confinement of the cosmic rays and the magnetic field in the center of clusters affects the gas of the intracluster medium.

scholarly journals Magnetic-reconnection-heated corona in active galactic nuclei: refined disc–corona model and application to broad-band radiation

2020 ◽  
Vol 495 (1) ◽  
pp. 1158-1171
Author(s):  
Huaqing Cheng ◽  
B F Liu ◽  
Jieying Liu ◽  
Zhu Liu ◽  
Erlin Qiao ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Accretion Rate ◽  
Broad Band ◽  
Limited Range ◽  
Relative Strength ◽  
Spectral Energy ◽  
X Ray ◽  
The Magnetic Field ◽  
Spectral Shapes

ABSTRACT A long-standing question in active galactic nucleus (AGN) research is how the corona is heated up to produce X-ray radiation much stronger than that arising from the viscous heating within the corona. In this paper, we carry out detailed investigations of magnetic-reconnection heating to the corona, specifically, studying how the disc and corona are self-consistently coupled with the magnetic field, and how the emergent spectra depend on the fundamental parameters of AGN. It is shown that diverse spectral shapes and luminosities over a broad bandpass from optical to X-ray can be produced from the coupled disc and corona within a limited range of the black hole mass, accretion rate, and magnetic field strength. The relative strength of X-ray emission with respect to optical/ultraviolet (UV) depends on the strength of the magnetic field in the disc, which, together with accretion rate, determines the fraction of accretion energy transported and released in the corona. This refined disc–corona model is then applied to reproduce the broad-band spectral energy distributions (SEDs) of a sample of 20 bright local AGNs observed simultaneously in X-ray and optical/UV. We find that, in general, the overall observed broad-band SEDs can be reasonably reproduced, except for rather hard X-ray spectral shapes in some objects. The radiation pressure-dominant region, as previously predicted for the standard accretion disc in AGN, disappears for strong X-ray sources, revealing that AGN accretion discs are indeed commonly stable as observed. Our study suggests the disc–corona coupling model involving magnetic fields to be a promising approach for understanding the broad-band spectra of bright AGNs.

scholarly journals Modelling multiwavelength emissions from PSR B1259–63/LS 2883: Effects of the stellar disc on shock radiations

2019 ◽  
Vol 627 ◽  
pp. A87 ◽  
Author(s):  
A. M. Chen ◽  
J. Takata ◽  
S. X. Yi ◽  
Y. W. Yu ◽  
K. S. Cheng
Keyword(s):  
Magnetic Field ◽  
Gamma Ray ◽  
Thermal Emission ◽  
Orbital Plane ◽  
Light Curves ◽  
Double Peak ◽  
Stellar Disc ◽  
X Ray ◽  
Pulsar Wind ◽  
Star Binary

PSR B1259–63/LS 2883 is an elliptical pulsar/Be star binary that emits broadband emissions from radio to TeV γ-rays. The massive star possesses an equatorial disc that is inclined with the orbital plane of the pulsar. Non-thermal emission from the system is believed to be produced by pulsar wind shock and double-peak profiles in the X-ray, and TeV γ-ray light curves are related to the phases of the pulsar passing through the disc region of the star. In this paper, we investigate the interactions between the pulsar wind and stellar outflows, especially with the presence of the disc, and present a multiwavelength modelling of the emission from this system. We show that the double-peak profiles of X-ray and TeV γ-ray light curves are caused by the enhancements of the magnetic field and soft photons at the shock during the disc passages. As the pulsar is passing through the equatorial disc, the additional pressure of the disc pushes the shock surface closer to the pulsar, which causes the enhancement of magnetic field in the shock, and thus increases the synchrotron luminosity. The TeV γ-rays due to the inverse-Compton (IC) scattering of shocked electrons with seed photons from the star are expected to peak around periastron, which is inconsistent with observations. However, the shock heating of the stellar disc could provide additional seed photons for IC scattering during the disc passages, and thus produces the double-peak profiles as observed in the TeV γ-ray light curve. Our model can possibly be examined and applied to other similar gamma-ray binaries, such as PSR J2032+4127/MT91 213, HESS J0632+057, and LS I+61°303.

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