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Abstract <p>The results of monitoring of radio pulsar B0531+21 in the Crab Nebula at the Pushchino Radio Astronomy Observatory of the Astrospace Center of the Physics Institute of the Russian Academy of Sciences at a frequency of 111 MHz are analyzed on a Large Phased Array (LPA) from September 2002 to December 2024. Giant pulsar pulses (GPs) are observed. GPs are analyzed using special programs that make it possible to determine the magnitude of the Faraday rotation measure (<i>RM</i>) and pulse broadening by scattering time τ<sub>sc</sub> simulating the passage of a pulse through a magnetically active plasma. The measured values of <i>RM</i> and GPs scattering are compared with the values of the dispersion measure according to the data of the Jodrell Bank Observatory (Great Britain). Unsteady processes were recorded, characterized by increased scattering in 2009–2013 and anomalous in 2020–2024. The correlation coefficient between the dispersion measure and the scattering time τ<sub>sc</sub> = 0.8 ± 0.1. The observed phenomena can be explained by eclipsing the pulsar by filaments and increasing turbulence in the plasma structures of the nebula. The correlation coefficient between the <i>RM</i> in filaments and the dispersion measure <i>dm</i> = –0.4 ± 0.2, between the magnetic induction in filaments and the dispersion measure <i>dm</i> = 0.2 ± 0.2, between the <i>RM</i> in filaments and the magnetic induction is 0.8 ± 0.1. Data processing showed that the <i>RM</i> value varied from ≈–47 rad/m<sup>2</sup> in 2006 to ≈–52 rad/m<sup>2</sup> in 2010. Since 2011, <i>RM</i> began to change dramatically and in 2012 amounted to ≈–44 rad/m<sup>2</sup>. Long-term <i>RM</i> variations are caused by magnetic field inhomogeneities and filaments density variations in the Crab Nebula. The magnetic induction in the interstellar medium in the direction of the pulsar was –0.96 ± 0.01 µG and in the nebula’s filaments it ranged within 130µG. Seasonal variations of the observed <i>RM</i> with the amplitude of 0.7 ± 0.1 rad/m<sup>2</sup> caused by the Earth’s ionosphere have been measured.</p>

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Мeasurements of the Faraday Rotation Measure in the Direction of Pulsar B0531+21 in the Crab Nebula at a Frequency of 111 MHz at the LPA

  • 期刊论文

  • 发表日期：

    2025年12月1日

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  • B. Ya. Losovsky

摘要

Abstract

The results of monitoring of radio pulsar B0531+21 in the Crab Nebula at the Pushchino Radio Astronomy Observatory of the Astrospace Center of the Physics Institute of the Russian Academy of Sciences at a frequency of 111 MHz are analyzed on a Large Phased Array (LPA) from September 2002 to December 2024. Giant pulsar pulses (GPs) are observed. GPs are analyzed using special programs that make it possible to determine the magnitude of the Faraday rotation measure (RM) and pulse broadening by scattering time τsc simulating the passage of a pulse through a magnetically active plasma. The measured values of RM and GPs scattering are compared with the values of the dispersion measure according to the data of the Jodrell Bank Observatory (Great Britain). Unsteady processes were recorded, characterized by increased scattering in 2009–2013 and anomalous in 2020–2024. The correlation coefficient between the dispersion measure and the scattering time τsc = 0.8 ± 0.1. The observed phenomena can be explained by eclipsing the pulsar by filaments and increasing turbulence in the plasma structures of the nebula. The correlation coefficient between the RM in filaments and the dispersion measure dm = –0.4 ± 0.2, between the magnetic induction in filaments and the dispersion measure dm = 0.2 ± 0.2, between the RM in filaments and the magnetic induction is 0.8 ± 0.1. Data processing showed that the RM value varied from ≈–47 rad/m2 in 2006 to ≈–52 rad/m2 in 2010. Since 2011, RM began to change dramatically and in 2012 amounted to ≈–44 rad/m2. Long-term RM variations are caused by magnetic field inhomogeneities and filaments density variations in the Crab Nebula. The magnetic induction in the interstellar medium in the direction of the pulsar was –0.96 ± 0.01 µG and in the nebula’s filaments it ranged within 130µG. Seasonal variations of the observed RM with the amplitude of 0.7 ± 0.1 rad/m2 caused by the Earth’s ionosphere have been measured.