Polarization Properties of Energetic Pulsars at Meterwavelengths
Polarization behavior shows a transition in the pulsar population, where energetic sources with higher spin-down energy loss, $\dot{E}\gt 1{0}^{34}$ erg s ^−1 , often have fractional linear polarization ( L / I ) close to 100%, while below this range L / I is usually lower than 50%. The polarization...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/addab1 |
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| author | Dipanjan Mitra Rahul Basu George I. Melikidze |
| author_facet | Dipanjan Mitra Rahul Basu George I. Melikidze |
| author_sort | Dipanjan Mitra |
| collection | DOAJ |
| description | Polarization behavior shows a transition in the pulsar population, where energetic sources with higher spin-down energy loss, $\dot{E}\gt 1{0}^{34}$ erg s ^−1 , often have fractional linear polarization ( L / I ) close to 100%, while below this range L / I is usually lower than 50%. The polarization behavior has been primarily studied at higher frequencies above 1 GHz, and in this work, we explore the single-pulse polarization behavior in pulsars with $\dot{E}\gt 5\,\times 1{0}^{33}$ erg s ^−1 at a lower frequency range of 300–750 MHz. The polarization behavior can be divided into two categories, the first with L / I > 70% where the polarization position angle (PPA) follows a single track, and a second group with L / I < 70% and scattered PPA behavior with or without orthogonal modes. However, there are some single pulses in the first category that also have lower L / I and exhibit the presence of two polarization modes along orthogonal tracks. The radio emission in pulsars arises due to coherent curvature radiation (CCR) from charge bunches, which develops due to nonlinear instabilities in the pulsar plasma forming charge separated envelope solitons. The CCR excites orthogonally polarized X and O modes oriented perpendicular and parallel to the magnetic field line planes, which detach in the plasma and propagate independently. The O mode is 7 times stronger than the X mode but gets damped in the medium. We show that incoherent mixing of the X and O modes with different levels of damping can reproduce the observed polarization features in the energetic pulsar population. |
| format | Article |
| id | doaj-art-fa847d8ee8064e6c9358b72f15cf7e3f |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| spelling | doaj-art-fa847d8ee8064e6c9358b72f15cf7e3f2025-08-20T02:38:27ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01987211910.3847/1538-4357/addab1Polarization Properties of Energetic Pulsars at MeterwavelengthsDipanjan Mitra0https://orcid.org/0000-0002-9142-9835Rahul Basu1https://orcid.org/0000-0003-1824-4487George I. Melikidze2https://orcid.org/0000-0003-1879-1659National Centre for Radio Astrophysics, Tata Institute of Fundamental Research , Pune 411007, India; Janusz Gil Institute of Astronomy, University of Zielona Góra , ul. Szafrana 2, 65-516 Zielona Góra, PolandJanusz Gil Institute of Astronomy, University of Zielona Góra , ul. Szafrana 2, 65-516 Zielona Góra, PolandJanusz Gil Institute of Astronomy, University of Zielona Góra , ul. Szafrana 2, 65-516 Zielona Góra, Poland; Evgeni Kharadze Georgian National Astrophysical Observatory , 0301 Abastumani, GeorgiaPolarization behavior shows a transition in the pulsar population, where energetic sources with higher spin-down energy loss, $\dot{E}\gt 1{0}^{34}$ erg s ^−1 , often have fractional linear polarization ( L / I ) close to 100%, while below this range L / I is usually lower than 50%. The polarization behavior has been primarily studied at higher frequencies above 1 GHz, and in this work, we explore the single-pulse polarization behavior in pulsars with $\dot{E}\gt 5\,\times 1{0}^{33}$ erg s ^−1 at a lower frequency range of 300–750 MHz. The polarization behavior can be divided into two categories, the first with L / I > 70% where the polarization position angle (PPA) follows a single track, and a second group with L / I < 70% and scattered PPA behavior with or without orthogonal modes. However, there are some single pulses in the first category that also have lower L / I and exhibit the presence of two polarization modes along orthogonal tracks. The radio emission in pulsars arises due to coherent curvature radiation (CCR) from charge bunches, which develops due to nonlinear instabilities in the pulsar plasma forming charge separated envelope solitons. The CCR excites orthogonally polarized X and O modes oriented perpendicular and parallel to the magnetic field line planes, which detach in the plasma and propagate independently. The O mode is 7 times stronger than the X mode but gets damped in the medium. We show that incoherent mixing of the X and O modes with different levels of damping can reproduce the observed polarization features in the energetic pulsar population.https://doi.org/10.3847/1538-4357/addab1Radio pulsars |
| spellingShingle | Dipanjan Mitra Rahul Basu George I. Melikidze Polarization Properties of Energetic Pulsars at Meterwavelengths The Astrophysical Journal Radio pulsars |
| title | Polarization Properties of Energetic Pulsars at Meterwavelengths |
| title_full | Polarization Properties of Energetic Pulsars at Meterwavelengths |
| title_fullStr | Polarization Properties of Energetic Pulsars at Meterwavelengths |
| title_full_unstemmed | Polarization Properties of Energetic Pulsars at Meterwavelengths |
| title_short | Polarization Properties of Energetic Pulsars at Meterwavelengths |
| title_sort | polarization properties of energetic pulsars at meterwavelengths |
| topic | Radio pulsars |
| url | https://doi.org/10.3847/1538-4357/addab1 |
| work_keys_str_mv | AT dipanjanmitra polarizationpropertiesofenergeticpulsarsatmeterwavelengths AT rahulbasu polarizationpropertiesofenergeticpulsarsatmeterwavelengths AT georgeimelikidze polarizationpropertiesofenergeticpulsarsatmeterwavelengths |