The distance to the pulsar B1818-04 and the distribution of turbulent interstellar plasma toward B0833-45, B1818-04, and B1933+16     

A. V. Pynzar’ 《Astronomy Reports》2017,61(5):417-427

The dependence of the scatter broadening of extragalactic sources on the dispersion measures of distant pulsars observed along nearby lines of sight and the dependence of broadening of pulsar pulses on the scatter broadening observed for the pulsars themselves and for extragalactic sources observed along nearby lines of sight are constructed and analyzed. These dependences can be used to study turbulent plasma in the Galaxy. The effective scattering layer in the direction toward the pulsar B1933+16 is located in the Sagittarius arm at a distance of ≈3.4 kpc from the observer, and has an extent of ≈0.55 kpc. The scatter broadening and pulse broadening of B0833-45 are due to the turbulent medium in the shell of the Gum Nebula. The distance from the pulsar to the center of the scattering layer is≈43 pc. Data on scattering of the radiation of the pulsar B1818-04 and of the extragalactic source J1821-0502, together with data on the distribution of OB stars in the direction toward this pulsar, are used to show that the distance to the pulsar is ≈0.6 kpc; an H II region around the O7V star HD 171198, located 0.42 kpc from the Sun, is responsible for the scattering of this pulsar’s radiation.  相似文献   

Gamma-ray bursts from a close pulsar binary system?     

Ya. N. Istomin 《Astronomy Reports》2005,49(6):446-449

The close neutron-star binary system comprised of the radio pulsars PSR J0737-3039 A,B is discussed. An analysis of the observational data indicates that the wind from pulsar A, which is more powerful than the wind from pulsar B, strongly distorts the magnetosphere of pulsar B. A shock separating the relativistic wind from pulsar A and the corotating magnetosphere of pulsar B should form inside the light cylinder of pulsar B. A weakly diverging “tail” of magnetic field is also formed, which stores a magnetic energy on the order of 10³⁰ erg. This energy could be liberated over a short time on the order of 0.1 s as a result of reconnection of the magnetic-force lines in this “tail,” leading to an outburst of electromagnetic radiation with energies near 100 keV, with an observed flux at the Earth of 4 × 10^?11 erg cm^?2 s^?2. Such outbursts would occur sporadically, as in the case of magnetic substorms in the Earth’s magnetosphere.  相似文献   

The radio pulsar J0205+6449 in the supernova remnant 3C 58     

V. M. Malofeev  I. F. Malov  O. I. Malov  A. P. Glushak 《Astronomy Reports》2003,47(5):413-421

The detection of pulsed radio emission from the recently discovered X-ray pulsar J0205+6449 in the young supernova remnant 3C 58 is reported together with the results of first studies of this emission. The observations were carried out at 111 and 88 MHz on radio telescopes of the Pushchino Observatory. The pulsar period, 65.68 ms, and period derivative, \(\dot P = 1.9 \times 10^{ - 13} \), have been confirmed. The integrated pulse profile at 111 MHz has been obtained and the flux density and spectral index α=2.8 measured. The pulsar dispersion measure DM=141 pc cm^?3 has been confirmed. This dispersion measure yields a distance to the pulsar of d=6.4 kpc, a factor of two or more greater than the previously favored distance to the supernova remnant 3C 58 (2.6 kpc). The problem of the age and distance of the pulsar-SNR system is discussed. If the age of the pulsar J0205+6449 is equal to that of the SNR (820 years), this pulsar is the youngest known radio pulsar. The synchrotron mechanism for the radio and X-ray emission is proposed to explain the lower radio and X-ray luminosity of this new pulsar compared to the Crab pulsar, which is similar to it in many ways. Optical emission with luminosity L_opt=10³¹ erg/s and gamma-ray emission with L_γ=7×10³⁵ erg/s are predicted, and the steep radio spectrum (α≈3) can be explained.  相似文献   

Refractive shift in the position of the pulsar PSR B0329+54, measured at 111, 610, and 2300 MHz     

A. E. Rodin  E. D. Starovoit 《Astronomy Reports》2017,61(11):942-947

The results of an analysis of timing data for the pulsar PSR B0329+54 obtained in 1968–2012 on the Large Scanning Antenna of the Pushchino Radio Astronomy Observatory at 111 MHz, the 64 m DSS-14 telescope of the Jet Propulsion Laboratory at 2.3 GHz, and the 64 m telescope of the Kalyazin Radio Astronomy Observatory at 610 MHz are presented. The astrometric and spin parameters of the pulsar are derived at a new epoch. The coordinates of the pulsar and its proper motion measured at the three frequencies differ. These differences have a systematic character, and are interpreted as a secular, refractive shift in the apparent position of the pulsar that arises because it is observed through large-scale inhomogeneities of the interstellar medium, leading to variations in the angle of refraction.  相似文献   

Curvature and non-resonance Compton gamma-ray emission of a radio pulsar with a non-dipolar magnetic field     

D. P. Barsukov  E. M. Kantor  A. I. Tsygan 《Astronomy Reports》2007,51(6):469-476

We consider the influence of a non-dipolar magnetic field on the gamma-ray emission from the polar regions of a radio pulsar. The pulsar is treated in a Goldreich-Julian model with a free flow of charge from the surface of the neutron star. When finding the intensity of the gamma-ray radiation of the pulsar tube, both curvature gamma-ray radiation from the primary electrons and non-resonance inverse Compton scattering of thermal photons from the polar cap on primary electrons are taken into account. When finding the height of the upper plate of the pulsar diode, we included only positrons created by the curvature radiation of primary electrons. We assumed that the polar cap is heated by the return positron current. The influence on the gamma-ray emission of variations in both the radius of curvature of the magnetic force lines and in the electric field due to the non-dipolarity of the magnetic field were taken into account. The presence of even weak non-dipolarity of the magnetic field leads to a sharp decrease in the intensity of the gamma-ray emission from the pulsar tube at energies 1–100 MeV, while the intensity of the inverse Compton radiation (at energies 1–100 GeV) varies only relatively weakly.  相似文献   

Effect of the pulsar-tube radius on the gamma-ray curvature radiation from the polar regions of radio pulsars with non-dipolar magnetic fields     

D. P. Barsukov  P. I. Polyakova  A. I. Tsygan 《Astronomy Reports》2009,53(1):86-94

The effect of the radius of the tube of open magnetic-field lines on the gamma-ray curvature radiation from the polar regions of a radio pulsar with a non-dipolar magnetic field is analyzed. The pulsar is considered in a polar-cap model with free electron emission from the neutron-star surface. The effect of the non-dipolar magnetic field on the radius of curvature of the field lines and the field intensity is taken into account. In connection with the creation of electron-positron pairs, we take into account only the birth of pairs by curvature radiation in the magnetic field. The small non-dipolarity of the field enables the radio pulsar not to turn off, even after a considerable decrease in the pulsar-tube radius. For instance, with a 20% non-dipolarity (ν = 0.2), a pulsar with B = 10¹³ G and P = 0.5 s can still operate even for a fivefold decrease in the pulsar-tube radius. A maximum is observed in the dependence of the electrostatic potential in the diode on the non-dipolarity parameter ν at ν ～ 0.5–0.7. The pulse profile in non-thermal X-ray emission for ν ～ 0.5–0.7 may look virtually the same as for ν ～ 0.1–0.2. Decreases in the pulsar-tube radius could be due to a structure of currents in the magnetosphere that results in the pulsar diode on the neutron-star surface occupying only a small fraction of the pulsar tube, with the remainder of the tube containing an outer annular gap. The pulsar-tube size is also affected by the presence of a circum-pulsar disk. A change in the pulsar-tube radius could also be due to an external magnetic field, associated with either a magnetic white dwarf or a circum-pulsar disk.  相似文献   

Giant pulses—The main component of the radio emission of the crab pulsar     

M. V. Popov  V. A. Soglasnov  V. I. Kondrat’ev  S. V. Kostyuk  Yu. P. Ilyasov  V. V. Oreshko 《Astronomy Reports》2006,50(1):55-61

The paper presents an analysis of dual-polarization observations of the Crab pulsar obtained on the 64-m Kalyazin radio telescope at 600 MHz with a time resolution of 250 ns. A lower limit for the intensities of giant pulses is estimated by assuming that the pulsar radio emission in the main pulse and interpulse consists entirely of giant radio pulses; this yields estimates of 100 and 35 Jy for the peak flux densities of giant pulses arising in the main pulse and interpulse, respectively. This assumes that the normal radio emission of the pulse occurs in the precursor pulse. In this case, the longitudes of the giant radio pulses relative to the profile of the normal radio emission turn out to be the same for the Crab pulsar and the millisecond pulsar B1937+21, namely, the giant pulses arise at the trailing edge of the profile of the normal radio emission. Analysis of the distribution of the degree of circular polarization for the giant pulses suggests that they can consist of a random mixture of nanopulses with 100% circular polarization of either sign, with, on average, hundreds of such nanopulses within a single giant pulse.  相似文献   

Unusual features of the millisecond pulsar 1937 + 21 at 406.9 MHz     

V. A. Soglasnov  A. D. Skulachev  N. D’Amico  S. Montebugnoli  K. V. Semenkov  A. Maccaferri  A. Cattani 《Astronomy Reports》2001,45(4):294-300

Observations of the millisecond pulsar PSR B1937 + 21 acquired in Summer 1997 with the Medicina cross telescope revealed two interesting features: the existence of long-lived microstructures persisting over several minutes, and a close relationship between the pulsar flux and pulse arrival times, due to refraction on a discrete inhomogeneity. The latter effect, though observed earlier at higher frequencies by the Nancay group, is rather peculiar at our low frequency.  相似文献   

Interferometric observations of 4C 21.53 and PSR 1937+214 at decameter wavelengths     

A. V. Megn  S. Ya. Braude  S. L. Rashkovskii  N. K. Sharykin  V. A. Shepelev  G. A. Inyutin  R. V. Vashchishin  A. I. Brazhenko  V. G. Bulatsen 《Astronomy Reports》2002,46(2):110-118

Preliminary resuts of interferometric observations of 4C 21.53 and PSR 1937+214 at 25 and 20 MHz are presented. The observations were obtained using the URAN-1 and URAN-2 interferometers, with baselines of 42.4 and 152.3 km. In addition to the pulsar radiation, which provides about 70% of the total flux of the object, radio emission from extended components with dimensions of several tens arcseconds has been detected for the first time. The angular size of the pulsar is 3″ at 25 MHz and 4″.8 at 20 MHz. The pulsar’s low-frequency spectrum deviates appreciably from the power law derived at higher frequencies.  相似文献   

Distribution of the relative plasma turbulence level in the galaxy     

A. V. Pynzar’  V. I. Shishov 《Astronomy Reports》2008,52(8):623-629

The statistical dependence of τ/(DM)² (the ratio of the broadening of a pulsar pulse due to scattering in the interstellar medium to the square of the pulsar’s dispersion measure) on the pulsar’s dispersionmeasure, Galactic coordinates, age, and the angular distance to the nearest supernova remnant are studied. This parameter describes the relative level of electron density fluctuations in the turbulent interstellar plasma. It is shown that the interstellar plasma turbulence level is three orders of magnitude higher in the spiral arms of the Galaxy than outside the arms. The plasma turbulence level is approximately an order of magnitude higher in the Galactic arms, in regions within ?0.3° of supernova remnants, than outside these regions. We conclude that the source of energy for the turbulence in the Galactic arms is supernova explosions in the denser medium there.  相似文献   

Evolution of the angle between the magnetic moment and the rotation axis of radio pulsars     

D. P. Barsukov  P. I. Polyakova  A. I. Tsygan 《Astronomy Reports》2009,53(12):1146-1154

It is shown that, when angular-momentum losses of a radio pulsar are represented as a sum of magnetic-dipole and current losses, the angle between the magnetic moment and rotation axis of the radio pulsar tends to some equilibrium value (near 45°). This process takes place on a timescale of the order of the pulsar’s characteristic age. Taking into account the non-dipolarity of the pulsar’s magnetic field changes this equilibrium angle.  相似文献   

The pulsar J1852+0040 in Kes 79 and the nature of central compact objects in supernova remnants     

I. F. Malov 《Astronomy Reports》2009,53(5):472-476

A possible model for the pulsar PSR J1852+0040 associated with the supernova remnant Kes 79 and detected in place of a central compact object in this remnant is discussed. The main observational properties of the pulsar can be understood as consequences of its weak surface magnetic field (B _s < 3 × 10¹¹ G) and short rotational period (P ～ 0.1 s). Its X-ray emission is thermal, and is generated in a small region near the surface of the neutron star due to cooling of the surface as the surface accretes matter from a relict disk surrounding the pulsar. The radio emission is generated in the outer layers of the pulsar magnetosphere by the synchrotron (cyclotron) mechanism. The optical luminosity of J1852+0040 is estimated to be L _opt < 10²⁸ erg/s. If the spectral features in another central compact object, 1E 1207.4+5209, are interpreted as electron cyclotron lines, this provides evidence for a weak surface magnetic field for this neutron star as well (B < 6 × 10¹⁰ G). The hypothesis that all central compact objects have weak surface fields makes it possible to explain the number of detected central compact objects, the absence of pulsar-wind nebulae associated with these objects, and the fact that no pulsar has yet been detected at the position of SN 1987a. We suggest that, after the supernova remnant has dissipated, the central compact object becomes a weak X-ray source (XDINS), whose weak emission is also due to the weakness of its magnetic field.  相似文献   

Anisotropic Scattering of the Radio Emission of the Pulsar B0833–45 in the Vela Supernova Remnant     

Popov  M. V.  Andrianov  A. S.  Burgin  M. S.  Zuga  V. A.  Rudnitskii  A. G.  Smirnova  T. V.  Soglasnov  V. A.  Fadeev  E. N. 《Astronomy Reports》2019,63(5):391-403

Very Long Baseline Interferometry (VLBI) observations of the pulsar B0833–45 have been carried out as part of the scientific program of the RadioAstron mission. Ground support was provided by the Long Baseline Array, which includes radio telescopes in Australia and other countries in the southern hemisphere. The VLBI observations of the pulsar are analyzed in order to derive the parameters characterizing the scattering of the pulsar radio emission: the angular size of the scattering disk, the spatial scale of the diffraction pattern, the drift velocity of this pattern relative to the observer, the pulse scattering time scale, and the characteristic scintillation time and frequency scales, as well as the index of the electrondensity fluctuation spectrum. Comparison of these values with the predictions of the theory of scattering on a thin screen enables the determination of the position of the effective screen along the line of sight. Estimates made using various methods give distances to the screen from the observer of 0.79 to 0.87 times the total distance to the pulsar. Although the position of the screen is beyond the boundary of the Vela supernova remnant, this object may play the dominant role in the scattering. The scattering disk is an ellipse with a 2:1 axis ratio and with the inferred position angle of the major axis being ≈ 50°, based on the changes in the visibility-function amplitude for various orientations of the projected baseline. This conclusion is supported by the shape of the visibility-function amplitude as a function of the delay.

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Two classes of glitches in the pulsar B1822-09     

T. V. Shabanova 《Astronomy Reports》2009,53(5):465-471

A large glitch has been detected in the pulsar B1822-09 (J1825-0935) using the LPA antenna of the Pushchino Observatory. This glitch occurred on January 15, 2007 and had a relative amplitude of Δν/ν ～ 1.2 × 10^?7 and a shape typical of classical glitches; i.e., it corresponded to a sudden, jump-like increase in the rotational velocity of the star within a day. The detection of this large, typical glitch together with the series of unusual, slow glitches discovered earlier in 1995–2004 indicates the existence of two classes of glitches in the rotational frequency of this pulsar. The presence of various classes of glitches in a single pulsar provides new possibilities for studying the mechanisms giving rise to glitches, which are a source of information about the internal structure of the neutron star. A possible interpretation of these results is discussed.  相似文献   

Irregularity in the period of the pulsar B1822-09     

T. V. Shabanova  Yu. P. Shitov 《Astronomy Reports》2007,51(9):746-755

The results of long-term monitoring of irregularies in the rotation rate of the pulsar B1822-09 (J1825-0935) are presented. Observations of the pulsar carried out since 1991 on the Large Phased Array of the Pushchino Radio Astronomy Observatory have revealed a new type of irregularity in the rotation, which has the form of “slow glitches” and is manifest as a gradual exponential growth in the rotation frequency of the star over several hundred days. In 1995–2004, five slow glitches in the rotation frequency were observed, with relative amplitudes of Δν/ν ～ (2.5-32) × 10^?9. Together with these unusual “slow glitches” in the rotation frequency, two modest ordinary glitches, associated with sudden, jump-like increases in the rotation frequency, were also observed. The observed irregularities in the rotation frequency of the pulsar are analyzed in detail, and possible interpretations of the results are discussed.  相似文献   

Gamma-ray curvature radiation from the polar regions of a radio pulsar with an axisymmetric magnetic field     

D. P. Barsukov  E. M. Kantor  A. I. Tsygan 《Astronomy Reports》2006,50(2):159-166

The influence of an axisymmetric magnetic field on the intensity, spectrum, and shape of a pulse of gamma-ray curvature radiation from the polar regions of a radio pulsar is investigated. The pulsar is considered in a Goldreich-Julian model with a free-electron emission from the neutron-star surface. The influence on the curvature radiation of variations of both the curvature of the magnetic field lines and the electric field due to the nondipolarity of the magnetic field are investigated. The presence of even modest nondipolarity (less than 10%) can lead to a sharp drop in the intensity of the gamma-ray curvature radiation, while the intensity of the X-ray curvature radiation (photon energies <100 keV) is affected only weakly.  相似文献   

Analysis of the scintillation pattern of the pulsar PSR B0329+54 based on VLBI data at 1650 MHz     

K. V. Semenkov  V. A. Soglasnov  M. V. Popov 《Astronomy Reports》2004,48(6):457-469

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The unusual profile of the radio pulsar Geminga     

V. M. Malofeev  O. I. Malov 《Astronomy Reports》2000,44(1):45-55

The results of observations of the radio emission profiles of the Geminga pulsar at 102.5, 87, 58, and 39 MHz are reported. Individual pulses are presented for the first time, and rare occasions of strong emission over the entire pulsar rotation period have been detected. A detailed analysis of the shapes, durations, and arrival phases of the pulses at 102.5 MHz is presented. These data reflect the unique character of the radio emission of Geminga.  相似文献   

A 12-Year Periodicity in the Pulse Arrival Times for the Pulsar PSR B0943+10     

Starovoit  E. D.  Suleymanova  S. A. 《Astronomy Reports》2019,63(4):310-315

An analysis of observations obtained over 26 years beginning in 1992 have indicated the appearance of sinusoidal variations with a period of about 12 years in the residual deviations of the pulse arrival times (PATs) for the pulsar PSR B0943+10. This behavior in the PAT residuals could be due to the influence of a planet orbiting the pulsar. These observations were carried out on the Large Scanning Antenna of the Pushchino Radio Astronomy Observatory at 112 MHz.

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Optimal filtration and a pulsar time scale     

A. E. Rodin  Din Chen 《Astronomy Reports》2011,55(7):622-628

An algorithm is proposed for constructing a group (ensemble) pulsar time based on the application of optimal Wiener filters. This algorithm makes it possible to separate the contributions of variations of the atomic time scale and of the pulsar rotation to barycentric residual deviations of the pulse arrival times. The method is applied to observations of the pulsars PSR B1855+09 and PSR B1937+21, and is used to obtain corrections to UTC relative to the group pulsar time PT_ens. Direct comparison of the terrestial time TT(BIPM06) and the group pulsar time PT_ens shows that they disagree by no more than 0.4 ± 0.17 μs. Based on the fractional instability of the time difference TT(BIPM06)-PT_ens, σ _z = (0.5 ± 2) × 10⁻¹⁵, a new limit for the energy density of the gravitational-wave background is established at the level Ω _g h ² ∼ 10⁻⁹.  相似文献