arXiv subjects

M. O. Toropov

Publications and source records attributed to M. O. Toropov.

6 recordsLinked to original sources

arXiv2025

Search for interpulses in a complete sample of pulsars at a frequency of 111 MHz

An interpulse search was carried out in a sample of 96 pulsars observed on the Large Phased Array (LPA) radio telescope in the Pushchino Multibeams Pulsar Search (PUMPS). The pulsar sample is complete for pulsars having a signal-to-noise ratio (S/N) in the main pulse ($MP$) greater than 40. To search for weak interpulses ($IP$), the addition of average profiles over an interval of up to 10 years was used. Interpulses were detected in 12 pulsars (12.5\% of the sample), of which 7 pulsars have an interpulse located near the $180^o$ phase relative to the main pulse (probable orthogonal rotators), and 5 have phases far from $180^o$ (probable coaxial rotators). The amplitude ratios of $IP/MP$ are in the range of 0.004-0.023, the median value is 0.01. Estimates of the observed number of coaxial and orthogonal rotators with $IP/MP \ge 0.01$ do not contradict the model according to which, during evolution, the magnetic axis and the axis of rotation become orthogonal.

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arXiv2025

Variations in the Radiation Intensity of Pulsar B0950+08: Nine Years of Monitoring at 110 MHz

The analysis of variations in the emission intensity of the pulsar B0950+08 from 2014 to 2022 with scales from minutes to years was carried out. The observations were obtained in a round-the-clock daily survey conducted on the Large Phased Array (LPA) radio telescope. The high variability of emission is shown not only from pulse to pulse, but also at scales greater than 3 min. The average value of the estimated amplitude of these variations in 3.2 minutes is 25~Jy, the modulation index is 1. The average relative amplitude of the interpulse (IP) is $2.00 \pm 0.28\%$ of the main pulse. In individual pulses, the amplitude of the interpulse may exceed the amplitude of the main pulse (MP), but this is a rare event. Emission is observed in almost the entire period of the pulsar. For the first time, the relative amplitude of emission between the main pulse and the interpulse (emission bridge) was measured. When averaging about 10 hours, it varies from $0.8\%$ to $1.31\%$ with an average value of $1.04 \pm 0.28\%$. A high correlation was found between MP and IP amplitude variations both when averaging profiles over 3.2 minutes and when averaging over years. This correlation is due to refractive interstellar scintillation. The frequency scale of IP diffraction interstellar scintillation was measured for the first time and it was shown that the spectral forms for IP and MP are well correlated and have the same frequency scale. There are strong variations in the frequency scale of scintillation $f_{dif}$ from session to session (time interval from one day) on scales of 200-800 kHz. The refractive scale of scintillation for 1-2 days has been determined. A modulation of emission with a characteristic scale of about 130 days was detected, which, apparently, is also associated with refractive scintillation.

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arXiv2025

Search for weak components in pulsar radiation

The search for weak components outside the main pulse (MP) in the radiation of pulsars at a frequency of 110 MHz observed on the LPA LPI telescope in the Pushchino Multibeam Pulsar Search (PUMPS) has been carried out. The sample included 96 pulsars, for which the signal-to-noise ratio (S/N) in the MP of the average profile during accumulation over 10 years was more than 40. It was found that PSR J1543+0929 has radiation for almost the entire period. The profile is three-component. The relative amplitudes of the lateral weak components are 0.013 and 0.026. For PSR J2234+2114, a precursor was detected that is $53^o$ away from MP.

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arXiv2023

Study of the variability and components of the pulsar B0823+26 at a frequency of 111 MHz

Studies of the pulsar B0823+26 have been carried out using the Large Phased Array (LPA) radio telescope. At time span of 5.5 years, the amplitudes of the main pulse (MP), postcursor (PC) and interpulse (IP) were evaluated in daily sessions lasting 3.7 minutes. It is shown that the ratio of the average amplitudes of MP in the bright (B) and quiet (Q) modes is 60. For B-mode, the average ratio of MP amplitudes to IP amplitudes is 65, and the ratio of MP amplitudes to PC amplitudes is 28. The number of sessions with a nulling is 4% of the total number of sessions. Structure function (SF) and correlation function analysis of MP, IP and PC amplitude variations of over a long-time interval allowed us to detect typical time scales 37 \pm 5 days and one year. The analysis of time variations shows that the time scale of 37 days is well explained by refraction on inhomogeneities of interstellar plasma, which is distributed mostly quasi-uniformly in the line-of-sight. This scintillation makes the main contribution to the observed variability. Analysis of the structure function showed that there may be a few days variability. This time scale does not have an unambiguous interpretation but is apparently associated with the refraction of radio waves on the interstellar medium. One-year variability time scale has not been previously detected. We associate its appearance with the presence of a scattering layer on a closely located screen at a distance of about 50-100 pc from the Earth.

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arXiv2023

Detection of two new RRATs at 111 MHz

A search for pulse signals in a area with declinations of $+52\degr <δ<+55\degr$ was carried out on the LPA LPI radio telescope. When processing ten months of observations recorded in six frequency channels with a channel width of 415 kHz and a total bandwidth of 2.5 MHz, 22 thousand events were found with a pronounced dispersion delay of signals over frequency channels, i.e. having signs of pulsar pulses. It turned out that the found pulses belong to four known pulsars and two new rotating radio transients (RRATs). An additional pulse search conducted in 32-channel data with a channel width of 78 kHz revealed 8 pulses for the transient J0249+52 and 7 pulses for the transient J0744+55. Periodic radiation of transients was not detected. The analysis of observations shows that the found RRATs are most likely pulsars with nullings, where the proportion of nulling is greater than 99.9\%.

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arXiv2022

Detection Statistics of Pulse Signals at Declinations from $+42^o$ to $+52^o$ at the Frequency 111 MHz

A search for pulse signals was carried out in a new sky area included in the monitoring program for the search for pulsars and transients. Processing of several months data recorded in six frequency channels with a total bandwidth of 2.5 MHz showed that, on average, 4 pulses per hour are observed in each of the 24 connected stationary beams. Of these pulses, 18.3% are similar to those of pulsars. They are visible in one or two neighboring beams and have a pronounced dispersion shift, that is, they are recorded first at a high and then at a low frequency, which indicates the possible passage of the signal through the interstellar medium. Almost 68% of such detected pulses belong to six known pulsars with dispersion measures from 9 to 141 $pc/cm^3$, and almost all of the remaining pulses are either noise of an unknown nature or artifacts of the proposed pulse separation technique. An additional study of the selected array of 3650 obvious pulsar pulses revealed 13 pulses belonging to four rotating radio transients (RRATs). Their dispersion measures are in the range of 17-51 $pc/cm^3$. A search for regular (periodic) RRAT emission was carried out using power spectra summed over 121 days. Periodic radiation was not detected, but for two RRATs, upper estimates of the periods were obtained from measurements of the time intervals between pulses. The upper estimates of the integrated flux density of the detected RRATs are in the range 2-4 mJy at the frequency 111 MHz.

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