Tearing-mediated Alfvénic Turbulence in a Relativistic Plasma
In astrophysical relativistic plasmas, Alfvénic turbulence exists across a wide range of scales. Similar to a nonrelativistic case, this turbulence can be influenced by the tearing instability. We argue that in an ultrarelativistic pair plasma the tearing effects become significant at the critical s...
Saved in:
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ada28a |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1832582739651461120 |
|---|---|
| author | Stanislav Boldyrev Nuno F. Loureiro |
| author_facet | Stanislav Boldyrev Nuno F. Loureiro |
| author_sort | Stanislav Boldyrev |
| collection | DOAJ |
| description | In astrophysical relativistic plasmas, Alfvénic turbulence exists across a wide range of scales. Similar to a nonrelativistic case, this turbulence can be influenced by the tearing instability. We argue that in an ultrarelativistic pair plasma the tearing effects become significant at the critical scale given by ${a}_{t}\sim {d}_{\mathrm{rel}}{\left({L}_{\perp }/{d}_{\mathrm{rel}}\right)}^{n/(4+5n)}$ , where L _⊥ represents the outer scale of the turbulence and d _rel the relativistic electron inertial scale. Here n = 1 corresponds to the Harris magnetic configurations, while n = 2 applies to localized (non-Harris) magnetic profiles of turbulence-generated current sheets. Below the critical scale, the energy spectrum of magnetic fluctuations steepens to W ( k ) dk ∝ k ^−(7 ^n ^+2)/3 ^n dk . However, this happens only when $\tilde{\sigma }\ll {\left({L}_{\perp }/{d}_{\mathrm{rel}}\right)}^{(2+4n)/(4+5n)}$ , where $\tilde{\sigma }$ is the magnetization parameter based on the magnetic fluctuations. If the opposite inequality holds, the Alfvénic cascade is instead affected by charge starvation at scales below ${a}_{\mathrm{ch}}\sim {d}_{\mathrm{rel}}{\left({d}_{\mathrm{rel}}/{L}_{\perp }\right)}^{1/3}{\tilde{\sigma }}^{2/3}$ , and the energy spectrum becomes steeper than W ( k ) dk ∝ k ^−3 dk . When d _rel is replaced by its nonrelativistic equivalent, our results agree with the nonrelativistic analysis of N. F. Loureiro & S. Boldyrev (2018). In the Harris case n = 1, they agree with the recent relativistic studies by I. Demidov & Y. Lyubarsky. |
| format | Article |
| id | doaj-art-3849b5f949ae40eca1264bb17646f977 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-3849b5f949ae40eca1264bb17646f9772025-01-29T09:57:19ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01979223210.3847/1538-4357/ada28aTearing-mediated Alfvénic Turbulence in a Relativistic PlasmaStanislav Boldyrev0https://orcid.org/0000-0001-6252-5169Nuno F. Loureiro1https://orcid.org/0000-0001-9755-6563Department of Physics, University of Wisconsin –Madison, Madison, WI 53706, USA; Space Science Institute , Boulder, CO 80301, USAPlasma Science and Fusion Center, Massachusetts Institute of Technology , Cambridge, MA 02139, USAIn astrophysical relativistic plasmas, Alfvénic turbulence exists across a wide range of scales. Similar to a nonrelativistic case, this turbulence can be influenced by the tearing instability. We argue that in an ultrarelativistic pair plasma the tearing effects become significant at the critical scale given by ${a}_{t}\sim {d}_{\mathrm{rel}}{\left({L}_{\perp }/{d}_{\mathrm{rel}}\right)}^{n/(4+5n)}$ , where L _⊥ represents the outer scale of the turbulence and d _rel the relativistic electron inertial scale. Here n = 1 corresponds to the Harris magnetic configurations, while n = 2 applies to localized (non-Harris) magnetic profiles of turbulence-generated current sheets. Below the critical scale, the energy spectrum of magnetic fluctuations steepens to W ( k ) dk ∝ k ^−(7 ^n ^+2)/3 ^n dk . However, this happens only when $\tilde{\sigma }\ll {\left({L}_{\perp }/{d}_{\mathrm{rel}}\right)}^{(2+4n)/(4+5n)}$ , where $\tilde{\sigma }$ is the magnetization parameter based on the magnetic fluctuations. If the opposite inequality holds, the Alfvénic cascade is instead affected by charge starvation at scales below ${a}_{\mathrm{ch}}\sim {d}_{\mathrm{rel}}{\left({d}_{\mathrm{rel}}/{L}_{\perp }\right)}^{1/3}{\tilde{\sigma }}^{2/3}$ , and the energy spectrum becomes steeper than W ( k ) dk ∝ k ^−3 dk . When d _rel is replaced by its nonrelativistic equivalent, our results agree with the nonrelativistic analysis of N. F. Loureiro & S. Boldyrev (2018). In the Harris case n = 1, they agree with the recent relativistic studies by I. Demidov & Y. Lyubarsky.https://doi.org/10.3847/1538-4357/ada28aPlasma astrophysicsMagnetic fields |
| spellingShingle | Stanislav Boldyrev Nuno F. Loureiro Tearing-mediated Alfvénic Turbulence in a Relativistic Plasma The Astrophysical Journal Plasma astrophysics Magnetic fields |
| title | Tearing-mediated Alfvénic Turbulence in a Relativistic Plasma |
| title_full | Tearing-mediated Alfvénic Turbulence in a Relativistic Plasma |
| title_fullStr | Tearing-mediated Alfvénic Turbulence in a Relativistic Plasma |
| title_full_unstemmed | Tearing-mediated Alfvénic Turbulence in a Relativistic Plasma |
| title_short | Tearing-mediated Alfvénic Turbulence in a Relativistic Plasma |
| title_sort | tearing mediated alfvenic turbulence in a relativistic plasma |
| topic | Plasma astrophysics Magnetic fields |
| url | https://doi.org/10.3847/1538-4357/ada28a |
| work_keys_str_mv | AT stanislavboldyrev tearingmediatedalfvenicturbulenceinarelativisticplasma AT nunofloureiro tearingmediatedalfvenicturbulenceinarelativisticplasma |