Radiation Process in Relativistic MHD Waves: The Case of Circularly Polarized Alfvén Waves
Turbulence in highly magnetized plasma can be relativistic and induce an electric field comparable to the background magnetic field. Such a strong electric field can affect the emission process of nonthermal electrons. As the first step toward elucidating the emission process in relativistic turbule...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad2f9c |
| _version_ | 1797201803040784384 |
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| author | Ryota Goto Katsuaki Asano |
| author_facet | Ryota Goto Katsuaki Asano |
| author_sort | Ryota Goto |
| collection | DOAJ |
| description | Turbulence in highly magnetized plasma can be relativistic and induce an electric field comparable to the background magnetic field. Such a strong electric field can affect the emission process of nonthermal electrons. As the first step toward elucidating the emission process in relativistic turbulence, we study the radiation process of electrons in relativistic circularly polarized Alfvén waves. While the induced electric field boosts the average energy of low-energy electrons with a Larmor radius smaller than the wavelength, the emissivity for such electrons is suppressed because of the elongated gyromotion trajectory. The trajectory of high-energy electrons is shaken by the small-scale electric field, which enhances the emissivity. Since the effective Lorentz factor of E × B drift is $\simeq \sqrt{2}$ in the circularly polarized Alfvén waves, the deviation from the standard synchrotron emission is not so prominent. However, a power-law energy injection in the waves can produce a concave photon spectrum, which is similar to the GeV extra component seen in GRB spectra. If the turbulence electric field is responsible for the GeV extra component in GRBs, the estimates of the typical electron energy and magnetic field should be largely altered. |
| first_indexed | 2024-04-24T07:53:20Z |
| format | Article |
| id | doaj.art-6f586e58d4414bd5a387ad2a75a82a63 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-04-24T07:53:20Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-6f586e58d4414bd5a387ad2a75a82a632024-04-18T08:55:57ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01965217810.3847/1538-4357/ad2f9cRadiation Process in Relativistic MHD Waves: The Case of Circularly Polarized Alfvén WavesRyota Goto0https://orcid.org/0000-0003-2825-8903Katsuaki Asano1https://orcid.org/0000-0001-9064-160XInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, JapanInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, JapanTurbulence in highly magnetized plasma can be relativistic and induce an electric field comparable to the background magnetic field. Such a strong electric field can affect the emission process of nonthermal electrons. As the first step toward elucidating the emission process in relativistic turbulence, we study the radiation process of electrons in relativistic circularly polarized Alfvén waves. While the induced electric field boosts the average energy of low-energy electrons with a Larmor radius smaller than the wavelength, the emissivity for such electrons is suppressed because of the elongated gyromotion trajectory. The trajectory of high-energy electrons is shaken by the small-scale electric field, which enhances the emissivity. Since the effective Lorentz factor of E × B drift is $\simeq \sqrt{2}$ in the circularly polarized Alfvén waves, the deviation from the standard synchrotron emission is not so prominent. However, a power-law energy injection in the waves can produce a concave photon spectrum, which is similar to the GeV extra component seen in GRB spectra. If the turbulence electric field is responsible for the GeV extra component in GRBs, the estimates of the typical electron energy and magnetic field should be largely altered.https://doi.org/10.3847/1538-4357/ad2f9cGamma-ray bursts |
| spellingShingle | Ryota Goto Katsuaki Asano Radiation Process in Relativistic MHD Waves: The Case of Circularly Polarized Alfvén Waves The Astrophysical Journal Gamma-ray bursts |
| title | Radiation Process in Relativistic MHD Waves: The Case of Circularly Polarized Alfvén Waves |
| title_full | Radiation Process in Relativistic MHD Waves: The Case of Circularly Polarized Alfvén Waves |
| title_fullStr | Radiation Process in Relativistic MHD Waves: The Case of Circularly Polarized Alfvén Waves |
| title_full_unstemmed | Radiation Process in Relativistic MHD Waves: The Case of Circularly Polarized Alfvén Waves |
| title_short | Radiation Process in Relativistic MHD Waves: The Case of Circularly Polarized Alfvén Waves |
| title_sort | radiation process in relativistic mhd waves the case of circularly polarized alfven waves |
| topic | Gamma-ray bursts |
| url | https://doi.org/10.3847/1538-4357/ad2f9c |
| work_keys_str_mv | AT ryotagoto radiationprocessinrelativisticmhdwavesthecaseofcircularlypolarizedalfvenwaves AT katsuakiasano radiationprocessinrelativisticmhdwavesthecaseofcircularlypolarizedalfvenwaves |