scholarly journals CoMStOC: The Coronal Magnetic Structures Observing Campaign

1990 ◽  
Vol 140 ◽  
pp. 20-20
Author(s):  
J.T. Schmelz
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Solar Corona ◽  
Magnetic Field Strength ◽  
Microwave Emission ◽  
X Ray ◽  
Magnetic Structures ◽  
The Magnetic Field ◽  
Microwave Data ◽  
Thermal Bremsstrahlung

The Coronal Magnetic Structures Observing Campaign (CoMStOC) was designed to measure the magnetic field strength and determine its structure in the solar corona. Simultaneous soft X-ray and microwave data separate the contributions of the two dominant microwave emission mechanisms - gyroresonance and thermal bremsstrahlung. Where gyroresonance dominates, the magnetic field can be determined.

scholarly journals Stretching of the Super-Elastic Double-Helix Geon. Wheeler´s Thermal Geons as Quanta of Heat and Momentum. Bohm´s Diffusion and the Heating of the Solar Corona and Heating of the Earth - Geon Engineering. Milgrom-Verlinde Constant. Mareš - Šesták constant

2020 ◽  
Vol 12 (2) ◽  
pp. 12
Author(s):  
Jiri Stavek
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Solar Corona ◽  
Magnetic Field Strength ◽  
Double Helix ◽  
David Bohm ◽  
The Earth ◽  
Highly Sensitive ◽  
Low Magnetic Field ◽  
The Magnetic Field

In our approach we have combined knowledge of Old Masters (working in this field before the year 1905), New Masters (working in this field after the year 1905) and Dissidents under the guidance of Louis de Broglie and David Bohm. Based on the great works of Julian Schwinger and John Archibald Wheeler we will study properties of geons formed by fusion of two soft x-ray particles (dyons) in the Schwarzschild gravitation core in our Sun at temperature 16 * 106 K. There are now several Teams that are able to achieve this fusion temperature in their special instruments (Tokamak, HL-2M Tokamak, Wendelstein 7-X, NIF, etc.) and to study properties of those formed geons. Thermal geons are with us all the time but they are very deeply hidden in our experiments. We have newly introduced Mareš - Šesták constant as the ratio of geon momentum to heat quantum of geon. The key information to enter into the World of geons was the empirical formula of David Bohm - the very well-known Bohm diffusion. From this formula we have extracted the amplitude, wavelength, frequency, quantum of the geon action, displacement law for geons, etc. It was found that geons are highly sensitive to the magnetic field strength. At a low magnetic field strength, the “inflation of geons” can occur. This effect could explain the Superheating of the Solar corona and the observed Heating of the Earth during two last centuries influenced by the changes in the Earth´s magnetic field. Geon engineering might modify the geon volume through the magnetic field strength. On the other hand, we were stimulated by the works of Mordehai Milgrom and Eric Verlinde and derived the Milgrom-Verlinde constant describing the gravitational field strength leading to the Newtonian gravitational constant on thermodynamic principles. The quantum of the geon momentum might open a new way how to understand gravitational phenomena. Can it be that Nature cleverly inserted geons into our experimental apparatuses and into our very-well known Old Formulae? We want to pass this concept into the hands of Readers of this Journal better educated in the Mathematics, Physics, and Thermodynamics.

scholarly journals CHANG-ES

2019 ◽  
Vol 632 ◽  
pp. A13 ◽  
Author(s):  
Y. Stein ◽  
R.-J. Dettmar ◽  
M. Weżgowiec ◽  
J. Irwin ◽  
R. Beck ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Flux Density ◽  
Magnetic Field Strength ◽  
Low Frequency ◽  
Transport Processes ◽  
Radio Continuum ◽  
Continuum Emission ◽  
X Ray ◽  
The Magnetic Field

Context. The radio continuum halos of edge-on spiral galaxies have diverse morphologies, with different magnetic field properties and cosmic ray (CR) transport processes into the halo. Aims. Using the Continuum HAloes in Nearby Galaxies – an EVLA Survey (CHANG-ES) radio continuum data from the Karl G. Jansky Very Large Array (VLA) in two frequency bands, 6 GHz (C-band) and 1.5 GHz (L-band), we analyzed the radio properties, including polarization and the transport processes of the CR electrons (CREs), in the edge-on spiral galaxy NGC 4013. Supplementary LOw-Frequency ARray (LOFAR) data at 150 MHz are used to study the low-frequency properties of this galaxy and X-ray data are used to investigate the central region. Methods. We determined the total radio flux densities (central source, disk, halo and total) as well as the radio scale heights of the radio continuum emission at both CHANG-ES frequencies and at the LOFAR frequency. We derived the magnetic field orientation from CHANG-ES polarization data and rotation measure synthesis (RM synthesis). Furthermore, we used the revised equipartition formula to calculate the magnetic field strength. Lastly, we modeled the processes of CR transport into the halo with the 1D SPINNAKER model. Results. The central point source dominates the radio continuum emission with a mean of ∼35% of the total flux density emerging from the central source in both CHANG-ES bands. Complementary X-ray data from Chandra show one dominant point source in the central part. The XMM-Newton spectrum shows hard X-rays, but no clear AGN classification is possible at this time. The radio continuum halo of NGC 4013 in C-band is rather small, while the low-frequency LOFAR data reveal a large halo. The scale height analysis shows that Gaussian fits, with halo scale heights of 1.2 kpc in C-band, 2.0 kpc in L-band, and 3.1 kpc at 150 MHz, better represent the intensity profiles than do exponential fits. The frequency dependence gives clear preference to diffusive CRE transport. The radio halo of NGC 4013 is relatively faint and contributes only 40% and 56% of the total flux density in C-band and L-band, respectively. This is less than in galaxies with wind-driven halos. While the SPINNAKER models of the radio profiles show that advection with a launching velocity of ∼20 km s−1 (increasing to ∼50 km s−1 at 4 kpc height) fits the data equally well or slightly better, diffusion is the dominating transport process up to heights of 1–2 kpc. The polarization data reveal plane-parallel, regular magnetic fields within the entire disk and vertical halo components indicating the presence of an axisymmetric field having a radial component pointing outwards. The mean magnetic field strength of the disk of NGC 4013 of 6.6 μG is rather small. Large-scale vertical fields are observed in the halo out to heights of about 6 kpc. Conclusions. The interaction and the low star formation rate (SFR) across the disk of NGC 4013 probably influence the appearance of its radio continuum halo and are correlated with the low total magnetic field strength. Several observable quantities give consistent evidence that the CR transport in the halo of NGC 4013 is diffusive: the frequency dependence of the synchrotron scale height, the disk/halo flux density ratio, the vertical profile of the synchrotron spectral index, the small propagation speed measured modeled with SPINNAKER, and the low temperature of the X-ray emitting hot gas.

scholarly journals On the magnetic field strength in the solar corona

2004 ◽  
Vol 2004 (IAUS223) ◽  
pp. 453-454 ◽  
Author(s):  
A.B. Delone ◽  
G.A. Porfir'eva ◽  
O.B. Smirnova ◽  
G.V. Yakunina
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Solar Corona ◽  
Magnetic Field Strength ◽  
The Magnetic Field

scholarly journals AXPs & SGRs: Magnetar or Quarctar?

2012 ◽  
Vol 8 (S291) ◽  
pp. 474-476
Author(s):  
Guojun Qiao ◽  
Xionwei Liu ◽  
Renxin Xu ◽  
Yuanjie Du ◽  
Jinlin Han ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Loss Rate ◽  
Gamma Ray ◽  
Radiation Energy ◽  
X Ray ◽  
Two Factors ◽  
Normal Method ◽  
The Magnetic Field

AbstractThe concept of a “magnetar” was proposed mainly because of two factors. First, the X-ray luminosity of Anomalous X-ray Pulsars (AXPs) and Soft Gamma-Ray Repeaters (SGRs) is larger than the rotational energy loss rate (Lx > Ėrot), and second, the magnetic field strength calculated from “normal method” is super strong. It is proposed that the radiation energy of magnetar comes from its magnetic fields. Here it is argued that the magnetic field strength calculated through the normal method is incorrect at the situation Lx > Ėrot, because the wind braking is not taken into account. Besides, the “anti-magnetar” and some other X-ray and radio observations are difficult to understand with a magnetar model.Instead of the magnetar, we propose a “quarctar”, which is a crusted quark star in an accretion disk, to explain the observations. In this model, the persistent X-ray emission, burst luminosity, spectrum of AXPs and SGRs can be understood naturally. The radio-emitting AXPs, which are challenging the magnetar, can also be explained by the quarctar model.

scholarly journals A joint XMM-NuSTAR observation of the galaxy cluster Abell 523: Constraints on inverse Compton emission

2019 ◽  
Vol 628 ◽  
pp. A83 ◽  
Author(s):  
F. Cova ◽  
F. Gastaldello ◽  
D. R. Wik ◽  
W. Boschin ◽  
A. Botteon ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Galaxy Cluster ◽  
X Ray ◽  
Radio Halo ◽  
Upper Limit ◽  
Inverse Compton ◽  
The Galaxy ◽  
The Magnetic Field

Aims. We present the results of a joint XMM-Newton and NuSTAR observation (200 ks) of the galaxy cluster Abell 523 at z = 0.104. The peculiar morphology of the cluster radio halo and its outlier position in the radio power P(1.4 GHz) – X-ray luminosity plane make it an ideal candidate for the study of radio and X-ray correlations and for the search of inverse Compton (IC) emission. Methods. We constructed bi-dimensional maps for the main thermodynamic quantities (i.e., temperature, pressure and entropy) derived from the XMM observations to describe the physical and dynamical state of the cluster’s intracluster medium (ICM) in detail. We performed a point-to-point comparison in terms of surface brightness between the X-ray and radio emissions to quantify their morphological discrepancies. Making use of NuSTAR’s unprecedented hard X-ray focusing capability, we looked for IC emission both globally and locally after properly modeling the purely thermal component with a multi-temperature description. Results. The thermodynamic maps obtained from the XMM observation suggest the presence of a secondary merging process that could be responsible for the peculiar radio halo morphology. This hypothesis is supported by the comparison between the X-ray and radio surface brightnesses, which shows a broad intrinsic scatter and a series of outliers from the best-fit relation, corresponding to those regions that could be influenced by a secondary merger. The global NuSTAR spectrum can be explained by purely thermal gas emission, and there is no convincing evidence that an IC component is needed. The 3σ upper limit on the IC flux in the 20−80 keV band is in the [2.2−4.0] × 10−13 erg s−1 cm−2 range, implying a lower limit on the magnetic field strength in the B >  [0.23 − 0.31] μG range. Locally, we looked for IC emission in the central region of the cluster radio halo finding a 3σ upper limit on the 20−80 keV nonthermal flux of 3.17 × 10−14 erg s−1 cm−2, corresponding to a lower limit on the magnetic field strength of B ≳ 0.81 μG.

scholarly journals X-Ray Emission from Cataclysmic Variables

1979 ◽  
Vol 53 ◽  
pp. 508-508
Author(s):  
D. Q. Lamb
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Classification Scheme ◽  
Accretion Rate ◽  
Cataclysmic Variables ◽  
X Rays ◽  
X Ray ◽  
Stellar Radius ◽  
The Magnetic Field

Many cataclysmic variables have been found to be hard, as well as soft, X-ray sources. Emission from the boundary layer of an optically thick accretion disk extending down to the stellar surface can, at outburst, produce soft X-rays, but the production of hard X-rays from such a disk is difficult to understand. We therefore conjecture that the sources which emit hard X-rays have magnetic fields and are, in general, rotating. We then propose a classification scheme for cataclysmic variables based on the size of the Alfven radius rA relative to the stellar radius R of the degenerate dwarf and the separation α of the binary system. We show that many of the varied characteristics displayed by the cataclysmic variable X-ray sources can be understood in terms of this ordering. We suggest that the AM Her Class (AM Her, AN UMa, W Pup, and 2A0311-23) have R ≪ α ≪ rA , the DQ Her Class (DQ Her, V533 Her, and AE Aqr) have R ≪ rA ≪ α, while the SS Cyg Class (SS Cyg, U Gem, EX Hya, and GK Per) have rA ≲ R ≪ α. Although rA depends on both the magnetic field strength of the degenerate dwarf ana the accretion rate, for comparable rates of accretion the ordering that we propose is essentially one of decreasing magnetic field strength.

JET FORMATION IN MICROQUASARS AND ACTIVE GALACTIC NUCLEI: MAGNETIC FIELD LIMITS

2008 ◽  
Vol 17 (10) ◽  
pp. 1931-1937
Author(s):  
M. M. KAUFMAN BERNADÓ ◽  
M. MASSI
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Accretion Rate ◽  
Plasma Pressure ◽  
X Ray ◽  
Mass Accretion Rate ◽  
Disk Material ◽  
The Magnetic Field

We introduce the use of a well-known parameter, the Alfvén Radius, R A , as a new tool to discern whether an X-ray binary system may undergo a microquasar phase, i.e. ejecting relativistic particles orthogonal to the accretion disk. We study what we call the basic condition, R A /R* = 1 in its dependency on the magnetic field strength and the mass accretion rate. With this basic condition we establish under which combination of parameters any class of accreting neutron stars could become a microquasar instead of confining disk-material down to the magnetic poles and creating the two emitting caps typical for an X-ray pulsar. In the case of black-hole accreting binaries we equate the magnetic field pressure to the plasma pressure in the last stable orbit (i.e. R A /R LSO = 1) and we get upper limits for the magnetic field strength as a function of the mass accretion rate and the black hole mass.

scholarly journals A First Spectroscopic Measurement of the Magnetic-field Strength for an Active Region of the Solar Corona

2020 ◽  
Vol 898 (2) ◽  
pp. L34 ◽  
Author(s):  
Ran Si ◽  
Tomas Brage ◽  
Wenxian Li ◽  
Jon Grumer ◽  
Meichun Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Field Strength ◽  
Solar Corona ◽  
Magnetic Field Strength ◽  
Spectroscopic Measurement ◽  
The Magnetic Field

scholarly journals XMM Observation of the Galaxy Cluster Abell 514

2006 ◽  
Vol 2 (S235) ◽  
pp. 256-256
Author(s):  
J. Weratschnig ◽  
S. Schindler ◽  
M. Gitti
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Galaxy Cluster ◽  
Radio Sources ◽  
X Ray ◽  
Rotation Method ◽  
The Galaxy ◽  
Interesting Object ◽  
The Magnetic Field

AbstractWe present XMM-Newton observations of the galaxy cluster Abell 514. This cluster shows a very complex X-ray morphology. Radio observations show that there are six radio sources located inside the cluster. This makes it possible to determine the magnetic field strength using the Faraday rotation method. This cluster is an example for the hierarchical growth of structure and a very interesting object for studying the correlation between magnetic field strength and X-ray properties.

scholarly journals Observational constraints on the magnetic field of the bright transient Be/X-ray pulsar SXP 4.78

2019 ◽  
Vol 490 (3) ◽  
pp. 3355-3364
Author(s):  
Andrey N Semena ◽  
Alexander A Lutovinov ◽  
Ilya A Mereminskiy ◽  
Sergey S Tsygankov ◽  
Andrey E Shtykovsky ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Field Strength ◽  
Power Spectrum ◽  
Magnetic Field Strength ◽  
Timing Analysis ◽  
Rapid Evolution ◽  
Periodic Oscillation ◽  
X Ray ◽  
The Magnetic Field

ABSTRACT We report results of the spectral and timing analysis of the Be/X-ray pulsar SXP 4.78 using the data obtained during its recent outburst with NuSTAR, Swift, Chandra, and NICER observatories. Using an overall evolution of the system luminosity, spectral analysis, and variability power spectrum we obtain constraints on the neutron star magnetic field strength. We found a rapid evolution of the variability power spectrum during the rise of the outburst, and absence of the significant changes during the flux decay. Several low frequency quasi-periodic oscillation features are found to emerge on the different stages of the outburst, but no clear clues on their origin were found in the energy spectrum and overall flux behaviour. We use several indirect methods to estimate the magnetic field strength on the neutron star surface and found that most of them suggest magnetic field B ≲ 2 × 1012 G. The strictest upper limit comes from the absence of the cyclotron absorption features in the energy spectra and suggests relatively weak magnetic field B < 6 × 1011 G.)

Sign in / Sign up

Export Citation Format

Share Document