scholarly journals Investigation of the Earth Ionosphere Using the Radio Emission of Pulsars

2013 ◽  
Vol 22 (1) ◽  
Author(s):  
O. M. Ulyanov ◽  
A. I. Shevtsova ◽  
D. V. Mukha ◽  
A. A. Seredkina
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Dispersion Measure ◽  
Pulsar Radio ◽  
The Earth ◽  
Lack Of Information ◽  
Rotation Measure ◽  
System Data ◽  
Gps System ◽  
The Impact

AbstractThe investigation of the Earth ionosphere both in a quiet and a disturbed states is still desirable. Despite recent progress in its modeling and in estimating the electron concentration along the line of sight by GPS signals, the impact of the disturbed ionosphere and magnetic field on the wave propagation still remains not sufficiently understood. This is due to lack of information on the polarization of GPS signals, and due to poorly conditioned models of the ionosphere at high altitudes and strong perturbations. In this article we consider a possibility of using the data of pulsar radio emission, along with the traditional GPS system data, for the vertical and oblique sounding of the ionosphere. This approach also allows to monitor parameters of the propagation medium, such as the dispersion measure and the rotation measure using changes of the polarization between pulses. By using a selected pulsar constellation it is possible to increase the number of directions in which parameters of the ionosphere and the magnetic field can be estimated.

scholarly journals DETERMINATION OF THE ROTATION MEASURE VALUE SIGN WHEN RECEIVING A SINGLE LINEAR POLARIZATION OF THE PULSAR RADIO EMISSION

2020 ◽  
Vol 25 (4) ◽  
pp. 253-267
Author(s):  
O. M. Ulyanov ◽  
◽  
A. I. Shevtsova ◽  
S. M. Yerin ◽  
◽  
...  
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Linear Polarization ◽  
Pulsar Radio ◽  
Absolute Value ◽  
The Earth ◽  
Rotation Measure ◽  
The Absolute ◽  
Pulsar Radio Emission

Purpose: The studies of pulsars allow enriching our knowledge in determination of parameters of both the exotic electron-positron plasma in the pulsar magnetosphere with strong magnetic field and the ordinary ion-electron plasma of the interstellar medium, which exists in a weak magnetic field. To determine the parameters of the both plasma types it is reasonable to use polarization characteristics of a pulsed radio emission of pulsars. An accurate determination of these characteristics is quite a complex problem. For its solving, primarily we have to determine two parameters of the propagation medium – its dispersion and rotation measures. Their absolute values can be determined with the relative precision of 10-4, but the problem of rotation measure value sign determination arises. This sign depends on the interstellar magnetic field direction along the line of sight. Hear, a new method of rotation measure value sign determination is proposed. Design/methodology/approach: Muller polarization matrices are usually used for determination of such a propagation parameter as the rotation measure absolute value. When only one linear polarization is received, using of these matrices allows quite accurate determining the absolute value of the rotation measure, but not the sign of this parameter due to a certain symmetry of these matrices with respect to the direction of the linear polarization rotation plane. If we complement the system of equations, which determines the rotation measure value, with some new additional components, which take into account the contributions of the Earth ionosphere and magnetosphere to the rotation measure value, one can notice that this contribution is always positive in the Southern magnetic hemisphere (the majority of the Northern geographical hemisphere) and is always negative in the Northern magnetic hemisphere (the majority of the Southern geographical hemisphere). Moreover, the absolute value of this contribution is maximal at noon and minimal at midnight, when the concentration of ions in the Earth ionosphere is maximal and minimal, respectively. Accounting for these regularities allows to determine not only the absolute value of the rotation measure, but also its sign by means of two independent time-shifted estimations of the observed absolute value of this parameter for various ionization degrees of the Earth ionosphere. Findings: We show that using of additional equations, which take into account the contribution of the Earth ionosphere and magnetosphere to the value of the rotation measure parameter, allows full determination of this parameter accounting for the sign of this value even for the antennas, which can record a single linear polarization only. This approach allows to determine all polarization parameters of the pulsar radio emission as well as of the pulsed or continuum polarized radio emission of other cosmic sources. Conclusions: The paper presents the results of measurement of the rotation measure for the two closest to the Earth pulsars, namely J0814+7429 (B0809+74), J0953+0755 (B0950+08), and the comparison of the proposed technique for this parameter determination with other existing techniques. Key words: pulse, dispersion measure, rotation measure, plasma, polarization, pulsar, radio telescope

scholarly journals 42. Solar cosmic radiation and the interstellar magnetic field

1958 ◽  
Vol 6 ◽  
pp. 404-419 ◽  
Author(s):  
A. Ehmert
Keyword(s):  
Magnetic Field ◽  
Solar Radiation ◽  
Cosmic Radiation ◽  
The Sun ◽  
High Latitudes ◽  
Narrow Angle ◽  
The Earth ◽  
Order Of Magnitude ◽  
The Impact ◽  
Impact Zones

The increase of cosmic radiation on 23 February 1956 by solar radiation exhibited in the first minutes a high peak at European stations that were lying in direct impact zones for particles coming from a narrow angle near the sun, whilst other stations received no radiation for a further time of 10 minutes and more. An hour later all stations in intermediate and high latitudes recorded solar radiation in a distribution as would be expected if this radiation fell into the geomagnetic field in a fairly isotropic distribution. The intensity of the solar component decreased at this time at all stations according to the same hyperbolic law (~t–2).It is shown, that this decreasing law, as well as the increase of the impact zones on the earth, can be understood as the consequence of an interstellar magnetic field in which the particles were running and bent after their ejection from the sun.Considering the bending in the earth's magnetic field, one can estimate the direction of this field from the times of the very beginning of the increase in Japan and at high latitudes. The lines of magnetic force come to the earth from a point with astronomical co-ordinates near 12·00, 30° N. This implies that within the low accuracy they have the direction of the galactic spiral arm in which we live. The field strength comes out to be about 0·7 × 10–6gauss. There is a close agreement with the field, that Fermi and Chandrasekhar have derived from Hiltner's measurements of the polarization of starlight and the strength of which they had estimated to the same order of magnitude.

scholarly journals Evolution of Multipolar Magnetic Fields in Isolated Neutron Stars and its effect on Pulsar Radio Emission

2000 ◽  
Vol 177 ◽  
pp. 265-266
Author(s):  
D. Mitra ◽  
S. Konar ◽  
D. Bhattacharya ◽  
A. V. Hoensbroech ◽  
J. H. Seiradakis ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Neutron Stars ◽  
Pulse Shape ◽  
Position Angle ◽  
Emission Region ◽  
Pulsar Radio ◽  
Significant Frequency ◽  
The Magnetic Field ◽  
Pulsar Radio Emission

AbstractThe evolution of the multipolar structure of the magnetic field of isolated neutron stars is studied assuming the currents to be confined to the crust. Lower orders (≤ 25) of multipole are seen to evolve in a manner similar to the dipole suggesting little or no evolution of the expected pulse shape. We also study the multifrequency polarization position angle traverse of PSR B0329+54 and find a significant frequency dependence above 2.7 GHz. We interpret this as an evidence of strong multipolar magnetic field present in the radio emission region.

scholarly journals On the magnetoionic environments of fast radio bursts

2020 ◽  
Vol 499 (1) ◽  
pp. 355-361 ◽  
Author(s):  
Wei-Yang Wang ◽  
Bing Zhang ◽  
Xuelei Chen ◽  
Renxin Xu
Keyword(s):  
Magnetic Field ◽  
Mean Value ◽  
Line Of Sight ◽  
Galactic Centre ◽  
Dispersion Measure ◽  
Radio Bursts ◽  
Host Galaxies ◽  
Surface Magnetic Field ◽  
Rotation Measure ◽  
The Mean

ABSTRACT Observations of the Faraday rotation measure, combined with the dispersion measure, can be used to infer the magnetoionic environment of a radio source. We investigate the magnetoionic environments of fast radio bursts (FRBs) by deriving their estimated average magnetic field strengths along the line of sight 〈B∥〉 in their host galaxies and comparing them with those of Galactic pulsars and magnetars. We find that for those FRBs with RM measurements, the mean 〈B∥〉 are $1.77^{+9.01}_{-1.48}\, \rm \mu G$ and $1.74^{+14.82}_{-1.55}\, \rm \mu G$ using two different methods, which is slightly larger but not inconsistent with the distribution of Galactic pulsars, $1.00^{+1.51}_{-0.60}\, \rm \mu G$. Only six Galactic magnetars have estimated 〈B∥〉. Excluding PSR J1745–2900 that has an anomalously high value due to its proximity with the Galactic Centre, the other five sources have a mean value of $1.70\, \rm \mu G$, which is statistically consistent with the 〈B∥〉 distributions of both Galactic pulsars and FRBs. There is no apparent trend of evolution of magnetar 〈B∥〉 as a function of age or surface magnetic field strength. Galactic pulsars and magnetars close to the Galactic Centre have relatively larger 〈B∥〉 values than other pulsars/magnetars. We discuss the implications of these results for the magnetoionic environments of FRB 121102 within the context of magnetar model and the model invoking a supermassive black hole, and for the origin of FRBs in general.

scholarly journals A way to detect the magnetic helicity using the observable polarized radio emission

2010 ◽  
Vol 6 (S274) ◽  
pp. 185-191
Author(s):  
Rodion Stepanov ◽  
Antonina Volegova
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Large Scale ◽  
Magnetic Helicity ◽  
Polarization Degree ◽  
Main Role ◽  
Frequency Range ◽  
Principal Solution ◽  
Large Scale Magnetic Field ◽  
Rotation Measure

AbstractWe discuss inverse problem of detection turbulence magnetic field helical properties using radio survey observations statistics. In this paper, we present principal solution which connects magnetic helicity and correlation between Faraday rotation measure and polarization degree of radio synchrotron emission. The effect of depolarization plays the main role in this problem and allows to detect magnetic helicity for certain frequency range of observable radio emission. We show that the proposed method is mainly sensitive to a large-scale magnetic field component.

How radial and quasi radial IMF impact the Earth's magnetopause's size, location, and shape. Does this impact generate Dawn-Dusk asymmetry in the magnetosheath?: Global 3D Kinetic Simulations. 

2021 ◽  
Author(s):  
Suleiman Baraka ◽  
Olivier Le Contel ◽  
Lotfi Ben-Jaffel ◽  
Bill Moore
Keyword(s):  
Magnetic Field ◽  
Maximum Density ◽  
Bow Shock ◽  
Temperature Anisotropy ◽  
Pressure System ◽  
Particle In Cell ◽  
The Earth ◽  
The Impact ◽  
Shape And Size ◽  
Dipole Tilt

<p>The boundary between the solar wind (SW) and the Earth’s magnetosphere, named the magnetopause (MP), is highly dynamic. Its location and shape can vary as a function of different SW parameters such as density, velocity, and interplanetary magnetic field (IMF) orientations. We employ a 3D kinetic Particle-In-Cell (IAPIC) code to simulate these effects.  We investigate the impact of radial (B = Bx) and quasi-radial (Bz < Bx, By) IMF on the shape and size of Earth’s MP for a dipole tilt of 31<sup>o</sup> using both maximum density steepening and pressure system balance methods for identifying the boundary. We find that, compared with northward or southward-dominant IMF conditions, the MP position expands asymmetrically by 8 to 22% under radial IMF. In addition, we construct the MP shape along the tilted magnetic equator and the OX axes showing that the expansion is asymmetric, not global, stronger on the MP flanks, and is sensitive to the ambient IMF. Finally, we investigate the contribution of SW backstreaming ions by the bow shock to the MP expansion, the temperature anisotropy in the magnetosheath, and a strong dawn-dusk asymmetry in MP location.</p>

Magnetic to the Core - Communicating paleomagnetism with hands-on activities

2020 ◽  
Author(s):  
Annique van der Boon ◽  
Greig Paterson ◽  
Janine Kavanagh ◽  
Andy Biggin
Keyword(s):  
Magnetic Field ◽  
General Public ◽  
Magnetic Polarity ◽  
Lessons Learned ◽  
Family Science ◽  
The Core ◽  
The Earth ◽  
Hands On ◽  
The Uk ◽  
The Impact

<p>With geoscience student numbers dwindling, there is a strong need for Earth scientists to enthuse a new generation of prospective students. We created several hands-on activities to introduce members of the general public of all ages to the fundamentals of, and current research in paleomagnetism. We developed these activities at different outreach events in the UK, such as a family science fair (at the Ness Gardens) and a holiday workshop (at the Victoria Gallery & Museum). In the first week of July, 2019, we contributed to the Royal Society Summer Science Exhibition, a science exhibition in London with almost 14,000 visitors of the general public, including many school groups. Visitors came from all educational backgrounds. We had a stand that consisted of 4 hands-on experiments, and an informative backdrop. The four activities allowed visitors to explore the range of tasks that a paleomagnetist does, from the collection and measurement of samples to understanding the behaviour of the Earth’s magnetic field. Visitors could measure real lavas from Iceland on a custom-built magnetometer that was designed specifically for outreach, and determine the magnetic polarity of the samples. We also created an information booklet with ’10 things you might not know about Earth’s magnetic field’, which is openly available under a CC-license. To measure the impact of our stand on visitors’ knowledge of paleomagnetism, we designed a quiz. Our results show that especially for school kids, our stand had a significant impact on their knowledge of the Earth’s magnetic field. In this contribution we share lessons learned through designing the ‘Magnetic to the Core’ stand, hands-on activities and evaluations.</p>

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