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The analysis of parameters of radio pulsars with periods s has been carried out. It was found that there is no clear dependence of on on the diagram. The lack of dependence can be explained within the disk model. It is shown that the pulse width decreases with increasing period for the sample considered. It is the opposite of the dependence in the generally accepted pulsar model. It indicates that the distance from the surface of the neutron star to the radio emission generation region in the studied population depends on the period or that the magnetic field in the generation region has a non-dipolar structure. The possibility of explaining the longest intervals between successive pulses in pulsars J0901–4046 and J0250+5854 by the influence of drift waves at the periphery of the magnetosphere has been considered. Within the framework of the drift model, the calculated rotation periods in these pulsars turn out to be several times shorter than the observed intervals between successive pulses. [ABSTRACT FROM AUTHOR]

The effect of a small-scale magnetic field on the heating of the polar cap of the pulsar J0901-4046 by the reverse current of positrons is considered. It is shown that under some configurations of a small-scale field, the luminosity of its polar cap can reach 1025 erg/s. [ABSTRACT FROM AUTHOR]

To study the normal pulsars based on the observations in radio and γ -ray bands, we try to investigate their classifications by the samples with the three different emission types, i.e., radio-only, γ -only and γ + radio emissions, and then discuss their physical causes. In the spin-down power range of E ˙ ∼ 10 36 − 10 39 erg ⋅ s − 1 , three types of normal pulsars exhibit the similar distributions of the spin period– P , spin-down power– E ˙ and characteristic age– τ , implying that they may belong to the same category of young pulsars. Moreover, in the range of E ˙ ∼ 10 33 − 10 36 erg ⋅ s − 1 , γ -only/ γ + radio normal pulsars share the similar distributions of P and τ values, and these two group sources exhibit the faster average spin periods (〈 P 〉 ∼ 0.23 s/ 〈 P 〉 ∼ 0.22 s), higher average spin-down powers (〈 E ˙ 〉 ∼ 2.00 × 10 35 erg ⋅ s − 1 / 〈 E ˙ 〉 ∼ 2.13 × 10 35 erg ⋅ s − 1 ) and smaller average characteristic ages (〈 τ 〉 ∼ 4.8 × 10 5 yr/ 〈 τ 〉 ∼ 4.1 × 10 5 yr) than radio-only normal pulsars (〈 P 〉 ∼ 0.42 s, 〈 E ˙ 〉 ∼ 3.2 × 10 34 erg ⋅ s − 1 and 〈 τ 〉 ∼ 1.64 × 10 6 yr). We suggest that γ -only/ γ + radio normal pulsars with E ˙ ∼ 10 33 − 10 36 erg ⋅ s − 1 are the young objects emitting γ -rays due to the high voltage in the radiation region. Meanwhile, after the temporal evolution of about τ ∼ 10 6 yr, these two group pulsars can be hardly detected with γ -rays due to the decrease of the radiation voltage, which will finally evolve into radio-only pulsars. [ABSTRACT FROM AUTHOR]

Using a relativistic plasma with an isotropic monoenergetic distribution of electrons and positrons as an example, we show that in the maser regime the maximum possible amplification of synchrotron radiation at a distance of one wavelength is achieved in a medium where the magnetic energy density is of the order of the particle energy density. This ratio of the energy densities corresponds to a (Harris-type) current sheet. We have obtained an electron Lorentz factor of 350 and a magnetic field strength of 10 kG in the maser radio emission region for the Crab pulsar. Our estimate suggests that the optical and coherent radio emissions of the object originate from one synchrotron source in the form of a current sheet. The diameter of the source must exceed the light-cylinder radius approximately by a factor of 6 for the maser wave field to interact with particles in the linear regime, in particular, to keep its phase velocity higher than the speed of light in a vacuum—a necessary condition for the synchrotron instability. [ABSTRACT FROM AUTHOR]

The pulsar J0901–4046 has a spin period s and is the most slowly rotating one among the isolated radio pulsars. We have considered the influence of a small-scale magnetic field in the off-centered dipole model on the polar cap heating by the reverse positron current in the inner gap of the pulsar. We have assumed that the electron–positron pairs in the gap are created in bound states, which then are broken by thermal photons from the stellar surface. [ABSTRACT FROM AUTHOR]

Calculations of angles between magnetic moments and rotation axes have been carried out for radio pulsars located at different distances from the "death line." We have shown that these angles decrease from 36° to 10° when pulsars move to the "death line". Such values correspond to kinematic ages from 1 to 10 millions of years. We also argue that radio luminosities of pulsars decrease for these ages. This means that radio pulsars fade out when their age increases. [ABSTRACT FROM AUTHOR]

We consider the evolutionary status of the recently discovered long-period radio sources PSR J0901-4046, GLEAM-X J1627-52, and GPM J1839-10. It is hypothesized that all three sources are radio pulsars. Within the framework of standard scenarios, it is thought that for the pulsar mechanism to operate, it is necessary to exclude the penetration of external matter into the light cylinder, which corresponds to the ejector stage. We show that for realistic properties of the interstellar medium the 76-second pulsar J0901-4046 must be at this stage, whereas the sources GLEAM-X J1627-52 and GPM J1839-10 with periods s can be at this stage only in the case of unrealistically high dipolar magnetic fields G. We also show that sources with periods s and magnetic fields G cannot be ejectors in a realistic interstellar medium. Thus, we predict that long-period radio pulsars with standard magnetic fields will not be discovered. [ABSTRACT FROM AUTHOR]

Assuming that the pulsar rotation is braking due to angular momentum loss by magnetodipole radiation, magnetic field inductions given in the ATNF catalog are corrected. To this end, we used the angles β between the magnetic moment and the rotation axis of central neutron stars, previously calculated by three methods. The dependence of the obtained magnetic fields on the pulsar age is analyzed. It is shown that the magnetic field is damped on average for the time of the order of 1 Myr. [ABSTRACT FROM AUTHOR]

Three methods were used to calculate the angles β between the magnetic moment and the axis of rotation of central neutron stars for 307 known radio pulsars. There is no explicit statistical dependence of the calculated angles β on the kinematic age of pulsars. It follows from this that either the indicated angle does not change noticeably with the age of the pulsar, or pulsars are born with an arbitrary inclination angle. [ABSTRACT FROM AUTHOR]

Angles between the rotation axis and the magnetic moment are calculated in two groups of radio pulsars with different periods ( s and s). Two methods have been used. The first method is based on the observed pulse widths and provides the minimum values of angle . The distributions of these angles differ significantly for these groups of objects. The second method uses polarization data to calculate more accurate values . There is a trend for bimodality in the distribution of values for pulsars with s. The closeness of the mean values ( for long-period pulsars and for sources with shorter periods) does not allow us to explain the previously discovered difference in the behavior of these two groups in the diagram by a decrease in the role of magnetic dipole radiation due to a decrease in . Our analysis showed that the observed difference can be explained by the different dependence of the pulsar wind and magnetic dipole braking on the period of the pulsar. The deceleration of pulsars with s is mainly caused by the pulsar wind. [ABSTRACT FROM AUTHOR]

The dependence dP/dt(P) is analyzed for three groups of pulsars with different period values: P > 2 s, 0.1 s < P < 2 s, and P < 0.1 s. Under the assumption of a slow decay of the magnetic field of neutron stars during their evolution, as well as the slow change in the angle between its magnetic moment and the rotation axis, we carried out the comparison of observed dependencies dP/dt(P) and the predictions of various models of slowing down the rotation of the pulsar. It is shown that long-period pulsars are braked by losses of the angular momentum by the accelerated particles (the pulsar wind). The mean value of the wind power Lp = 2.3 × 1030 erg/s is needed to explain the observed statistical dependence. For pulsars with intermediate values of the period, it is necessary to take into account the joint action of magnetic dipole radiation and the pulsar wind. Pulsars with P < 0.1 s are divided into three non-overlapping groups: P < 10 ms, P = 10–100 ms at dP/dt < 10–16 and P = 10–100 ms for dP/dt > 10–16. In the first of them, the magnetic dipole braking and the pulsar wind work together with the predominance of the first mechanism. The slowing down of rotation in the second group is caused by a pulsar wind, in the third one by magnetic dipole radiation. [ABSTRACT FROM AUTHOR]

The parameters of pulsars with detected giant pulses (GPs) and the known models proposed to describe the GP phenomenon have been analyzed. The angles between the magnetic moment and the rotation axis of the neutron star have been estimated for such pulsars. This parameter is important in a number of analyzed models. It is noted that there is likely no unified model to explain all the features of GPs. Kontorovich's model and the model by Machabeli et al. appear to be the most promising for describing GPs. In the first model, GPs are formed in a vacuum gap near the surface of a neutron star. The existence of such a gap and the presence of electric fields in it is considered generally accepted today. The second model explains GPs through nonlinear processes in plasma during the generation of drift waves at the periphery of the pulsar's magnetosphere. The appearance of such waves, apparently, can also be considered inevitable, and their role in the observed phenomena can be significant. A more detailed development of each of the models is necessary to draw more definite conclusions about their role in the formation of GPs. This problem seems all the more relevant in light of the possibility of using the GP phenomenon to explain fast radio bursts. [ABSTRACT FROM AUTHOR]

The birth function of neutron stars in magnetic field is estimated for two models of the evolution of radio pulsars corresponding to different directions of evolution of the inclination angle of the magnetic axis to the rotation axis (toward small angles or angles close to ). We show that for both models at magnetic fields G it is a power law with a break near G. At the same time, however, the number of born pulsars with a super-strong magnetic field G in the first model turns out to be smaller than that in the second one by an order of magnitude. [ABSTRACT FROM AUTHOR]

The X-ray luminosity and temperature of the polar cap heated by the back flux of positrons from a radio pulsar with a period P ∼ 1 s and a magnetic field B ~ 10 G have been estimated. An additional source of X-ray emission-a thin, hotter semiring on the polar-cap periphery-is shown to also exist. It is heated by the back flux of electrons from the light cylinder. Furthermore, the electric field near the hot semiring accelerates the ions of the surface layer that leave the neutron-star magnetosphere. The semiring area is smaller than the polar-cap area approximately by a factor of 100, i.e., at the same luminosity the temperature is higher by a factor of 3. The observed X-ray emission from old radio pulsars is the emission from thin hot polar-cap semirings. The emission from the polar caps themselves is strongly attenuated by interstellar absorption. [ABSTRACT FROM AUTHOR]

A star burns its nuclear fuel and balances gravitation by the pressure of the heated gas, during its active lifetime. After the exhaustion of the nuclear fuel, a low mass starfinds peace as a 'white dwarf', where the pressure support against gravitation is provided by Fermi-degenerate electrons. However, for massive stars, the gravitational squeeze becomes so severe that in the final phase of evolution, the average density approximately equals the nuclear density. At such densities, most of the protons combine with electrons to convert themselves into neutrons. A 'neutron star', composed of such neutron-rich material, is host to some fascinating physics arising out of its amazingly compact state of matter (where a solar mass is packed inside a sphere of radius ~ 10Km). [ABSTRACT FROM AUTHOR]

Pulsar J0810+37 with a period of 1.2483 s is detected at a frequency of 111 MHz during the pulsar search at the Big Scanning Antenna (BSA) radio telescope of the Lebedev Physical Institute [1]. In this paper, we present the results of the detailed study of radio emission from J0810+37 which exhibits a rare nulling effect of different durations in a very wide time interval with an average nulling fraction in "switch-on" days 〈NF〉 = 38%; considering "switch-off" days, 〈NF〉 = 74%, since radio emission from this source is interrupted on average by 2–3 days, and then it again revives on average for 1–2 days. The "switch-off" periods reach 7 days. [ABSTRACT FROM AUTHOR]

Symmetries play important roles in modern theories of physical laws. In this paper, we review several experimental tests of important symmetries associated with the gravitational interaction, including the universality of free fall for self-gravitating bodies, time-shift symmetry in the gravitational constant, local position invariance and local Lorentz invariance of gravity, and spacetime translational symmetries. Recent experimental explorations for post-Newtonian gravity are discussed, of which, those from pulsar astronomy are highlighted. All of these tests, of very different aspects of gravity theories, at very different length scales, favor to very high precision the predictions of the strong equivalence principle (SEP) and, in particular, general relativity which embodies SEP completely. As the founding principles of gravity, these symmetries are motivated to be promoted to even stricter tests in future. [ABSTRACT FROM AUTHOR]

Using a well-known method for calculating the propagation of waves in an inhomogeneous medium, we have managed to reduce the problem of wave propagation in pulsar magnetospheres to a system of two ordinary differential equations that allow the polarization characteristics of the radio emission to be quantitatively described for any magnetic field structure and an arbitrary density profile of the outflowing plasma. We confirm that for ordinary pulsars (period P ∼ 1 s, magnetic field B0 ∼ 1012 G, particle production multiplicity parameter λ ∼ 104), the polarization is formed inside the light cylinder at a distance of the order of a thousand neutron star radii. For reasonable magnetic field strengths and plasma densities on the emission propagation path, the degree of circular polarization is found to be ∼5–20%, in good agreement with observations. [ABSTRACT FROM AUTHOR]

We analyze the statistical distribution of neutron stars at the stage of a supersonic propeller. An important point of our analysis is allowance for the evolution of the angle of inclination of the magnetic axis to the spin axis of the neutron star for the boundary of the transition to the supersonic propeller stage. We have determined the spin period distributions of pulsars at the propeller stage for two models: the model with hindered particle escape from the stellar surface and the model with free particle escape. As a result, we have shown that consistent allowance for the evolution of the inclination angle in the region of extinct radio pulsars for the two models leads to an increase in the total number of neutron stars at the supersonic propeller stage. This increase stems from the fact that when allowing for the evolution of the inclination angle χ for neutron stars in the region of extinct radio pulsars and, hence, for the boundary of the transition to the propeller stage, this transition is possible at shorter spin periods (P ∼ 5–10 s) than assumed in the standard model.© 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

We study the statistical distribution of extinct radio pulsars at the stage of an ejector. An important element that distinguishes our study from other works is a consistent allowance for the evolution of the angle of inclination of the magnetic axis to the spin axis. We determined the distribution of extinct radio pulsars in spin period for two models: the model with hindered particle escape from the neutron-star surface and the model with free particle escape. The total number of extinct radio pulsars is shown to be much smaller than that in the model in which the evolution of the angle of axial inclination is disregarded. This is because when the evolution of the angle of axial inclination is taken into account, the transition to the stage of a propeller occurs at much shorter neutron-star spin periods (P ∼ 5–10 s) than assumed previously.© 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

The magnitude of the anomalous torque acting on a rotating magnetized ball in vacuum is specified. Its value is shown to depend on the magnetic field structure inside the body. [ABSTRACT FROM AUTHOR]

It is shown that the drift waves near the light cylinder can cause the modulation of emission with periods of order several seconds. These periods explain the intervals between successive pulses observed in AXPs, SGRs and radio pulsars with long periods. The model under consideration gives the possibility to calculate real rotation periods P of host neutron stars. It is shown that P≤1 s for the investigated objects. The magnetic fields at the surface of the neutron star are of order 1011–1013 G and equal to the fields usual for the known radio pulsars. [ABSTRACT FROM AUTHOR]

The stationary axisymmetric force-free magnetosphere of a pulsar is considered. We present an exact dipolar solution of the pulsar equation, construct the magnetospheric model on its basis and examine its observational support. The new model has toroidal rather than common cylindrical geometry, in line with that of the plasma outflow observed directly as the pulsar wind nebula at much larger spatial scale. In its new configuration, the axisymmetric magnetosphere consumes the neutron star rotational energy much more efficiently, implying re-estimation of the stellar magnetic field, Bnew0=3.3×10−4B/P, where P is the pulsar period. Then the 7-order scatter of the magnetic field derived from the rotational characteristics of the pulsars observed appears consistent with the cotχ-law, where χ is a random quantity uniformly distributed in the interval [0,π/2]. Our result is suggestive of a unique actual magnetic field strength of the neutron stars along with a random angle between the magnetic and rotational axes and gives insight into the neutron star unification on the geometrical basis. [ABSTRACT FROM AUTHOR]