Begell House Inc.
Radio Physics and Radio Astronomy
RPRA
2152-274X
2
1
2011
EVOLUTION OF RADIO EMISSION OF CASSIOPEIA A SUPERNOVA REMNANT BY FIFTY-YEAR OBSERVATIONS NEAR FREQUENCIES 12.6, 14.7, 16.7, 20, AND 25 MHZ
3-14
10.1615/RadioPhysicsRadioAstronomy.v2.i1.10
V. P.
Bovkoon
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
I. N.
Boobnov
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
I. N.
Zhouck
Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkiv, Ukraine
Alexandr A.
Konovalenko
Institute of Radio Astronomy of the National Academy of Sciences of Ukraine
supernova remnant
evolution of radio emission
Cassiopeia A
decameter wavelengths
The results of measurements in the ratios of flux densities of Cas A supernova remnant and Cyg A radio galaxy during 1959.5−2009.4 at frequencies 12.6, 14.7, 16.7, 20, and 25 MHz are shown. The radio telescopes used in these measurements are briefly mentioned. Strong variations in Cas A flux densities at decameter wavelengths are shown to be observed. The average drop rate of Cas A flux density for a 50-yr period has been determined. For the decameters, it makes (0.81 ± 0.04) % per year, being frequency independent within the measuring errors.
SEARCH FOR PULSED RADIO EMISSION FROM X-RAY DIM ISOLATED NEUTRON STARS AT DECAMETER WAVELENGTHS
15-21
10.1615/RadioPhysicsRadioAstronomy.v2.i1.20
V. V.
Zakharenko
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
A. V.
Markova
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
Y. Y.
Vasylyeva
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
XDINS
decameter wavelengths
upper limit of radio emission
This paper mainly deals with the search for radio emission of x-ray dim isolated neutron stars (XDINS) at decameter wavelengths seeing that some discrepant data about presence or absence of pulsed emission from them have appeared. The reason for the search experiments became equipping of the UTR-2 radio telescope with a new broadband highly sensitive receiver possessing a large dynamic range, and also development of the software package for searching the pulse and recurrent emission. The results obtained give no ground to suggest the presence of pulsed radio emission from sources 1RXS J1308+21 and 1RXS J2143+06 at the level above 4σ with σ = 2.5 mJy. This can be explained by both the absence of radio emission and the inverse spectrum slope at low frequencies or change of signal character. The high sensitivity of the experiment and of the developed package of search programs has been proved by reliable detection, with > 10σ, of the "test" weak pulsar B1508+55 which has never been detected at decameter waves.
FOCUSING OF THE QUASAR RADIATION IN THE GRAVITATIONAL FIELD OF A MICROLENS-STAR LOCATED IN A MACROLENS-GALAXY: 1. CONSTRUCTION OF THE SOLUTION BASED ON THE SOBOLEV FORMULA
23-35
10.1615/RadioPhysicsRadioAstronomy.v2.i1.30
L. A.
Berdina
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
A. A.
Minakov
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
microlens-star
macrolens-galaxy
quasars
Sobolev formula
dark matter
magnification factor
Studying of the microlensing effect is among promising approaches to solving the problem of detecting the dark matter in the Universe. In the first part of the paper, a solution is constructed of the problem of analyzing the focusing effect of the quasar radiation which occurs in the gravitational field of a microlens-star located inside a macrolens-galaxy. The effect is analyzed with the use of the Sobolev method which allows investigating changes of the focusing properties of the gravitational field of the microlens in dependence on its position in the galaxy.
ENERGY OF ATMOSPHERIC GRAVITY WAVES AS DETERMINED FROM IN SITU SATELLITE MEASUREMENTS
37-45
10.1615/RadioPhysicsRadioAstronomy.v2.i1.40
Alla K.
Fedorenko
Institute of Space Research of National Academy of Sciences of Ukraine and State Space Agency of Ukraine, Kiev
atmospheric gravity waves
satellite measurements
potential energy
atmospheric gas components
thermobaric energy
acoustic energy
A technique is suggested for determining spatial energy density distribution of Atmospheric Gravity Waves (AGW) from direct satellite measurements. The technique is capable of estimating the potential energy of the waves using either of the two kinds of satellite data, which are 1) mass-spectrometer measurements of concentrations of the atmospheric gas species and 2) synchronous measurements of the total density and temperature. The distribution of the potential energy components, acoustic and thermobaric ones, as obtained for AGWs observed from the Dynamics Explorer 2 satellite is analyzed. Several kinds of AGWs, with respect to the energy proportions, are identified at altitudes of the F2 ionospheric region. These are polar waves with nearly equal amounts of the two potential energy components, middle latitude and low latitude ones which are characterized by the prevailing amount of the thermobaric energy and nearly equal levels of the potential energy. The maximum energy density of AGWs is observed in polar regions.
DETERMINATION OF LAYERED STRUCTURE PARAMETERS BY A SCATTERING MATRIX RECOVERED FROM KNOWN REFLECTION COEFFICIENTS
47-62
10.1615/RadioPhysicsRadioAstronomy.v2.i1.50
Z. T.
Nazarchuk
Karpenko Physical-Mechanical Institute, National Academy of Sciences of Ukraine
A. T.
Synyavskyy
Karpenko Physico-Mechanical Institute, National Academy of Sciences of Ukraine
inverse scattering
layered structures
scattering matrix
A new method for determining both layers' permittivity and thickness of a plane layered structure is proposed. The reflection coefficient of a plane electromagnetic wave is considered as the problem's given data. The method employs an approach to reconstruction of the frequency dependences of all scattering matrix elements in a limited waveband. The scattering matrix has been recovered by recalculation of the reflection coefficients measured for this structure in free space and on a perfectly-conducting substrate. A high accuracy in both permittivity and thickness determination is achieved due to identification of spectral factors which are singled out from the scattering matrix elements and expressed as a finite series of continuous complex exponents.
THE ELECTROMAGNETIC FIELD OF A MAGNETIC CURRENT STRIP ON A FINITE CONE SURFACE
63-70
10.1615/RadioPhysicsRadioAstronomy.v2.i1.60
O. B.
Trishchuk
Karpenko Physico-Mechanical Institute, National Academy of Sciences of Ukraine
D. B.
Kuryliak
G.V. Karpenko Physical-Mechanical Institute, National Academy of Sciences of Ukraine 5, Naukova St., L'viv 79060, Ukraine
antenna
wave diffraction
magnetic current distribution
magnetic current strip
magnetic current ring
radiating slot
semi-inversion technique
radiation pattern
A symmetric electromagnetic field produced by a magnetic current strip mounted on a finite conducting conical surface has been studied. Radiation pattern dependences on the strip current distribution have been traced, the cone edge influence on the diffraction properties of this radiating system examined. Magnetic current strips and cone-through slots, both on a semi-infinite conical surface, are compared for their normalized radiation patterns, lending support to the validity of the magnetic strip current model for actual slots. The solution approach adopts the semi-inversion technique.
RESONANT RISE OF NATURAL MAGNETIC-TYPE OSCILLATION QUALITY IN AN OPEN RESONATOR WITH A SPHERICAL METAL INSERT
71-76
10.1615/RadioPhysicsRadioAstronomy.v2.i1.70
Yu. V.
Svishchov
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
open resonator
eigenfrequency
eigenoscillation quality
Numerical experiment results on the properties of natural magnetic-type oscillations of an open resonator (OR) are presented for a spherical-mirror structure with a perfectly conducting spherical insert. An effect has been revealed and examined that OR natural-oscillation quality can resonantly rise by several orders of magnitude. An insight into the nature of this effect is suggested.
FREQUENCY-SELECTIVE PROPERTIES OF A PLANE SCREEN OF FINITE THICKNESS WITH COAXIAL-SECTOR APERTURES
77-83
10.1615/RadioPhysicsRadioAstronomy.v2.i1.80
J. V.
Antonenko
Institute of Radio Astronomy, National Academy of Sciences of Ukraine, 4 Mystetstv St.,
Kharkiv 61002, Ukraine
A. V.
Gribovsky
Institute of Radio Astronomy, National Academy of Sciences of Ukraine, 4 Mystetstv St.,
Kharkiv 61002, Ukraine
operator method
coaxial-sector aperture
reflection coefficient
scattering matrix
The operator method is used to investigate frequency dependences of the absolute value of the reflection coefficient for a screen with coaxial-sector apertures in the cases of normal and oblique incidence of plane electromagnetic linearly-polarized TE- and TM-waves. The frequency-selective properties of the screen are compared with those of a screen with rectangular apertures.
CUMULANT DESCRIPTION OF AN ARBITRARY TRUNCATED LÉVY FLIGHT
85-92
10.1615/RadioPhysicsRadioAstronomy.v2.i1.90
D. V.
Vinogradov
Himex Ltd.
random walk
stochastic process
truncated Lévy flight
cumulants
The cumulant expansion method is used to analyze the properties of an arbitrary truncated Lévy flight process. A set of cumulants has been found, suitable for characterizing the arbitrary truncated Lévy distribution, and their dependence established upon the shape of the truncation. The effect of the shape of truncation upon the Gaussian and the Lévy regimes of the process has been investigated.