Unusual Intraburst Variations of Polarization States in FRB 20210912A and FRB 20230708A: Effects of Plasma Birefringence?
Fast radio bursts (FRBs) are highly energetic events of short-duration intense radio emission, the origin of which remains elusive. Polarization of the FRB signals carries information about the emission source as well as the magnetoionic media the signal passes through before reaching terrestrial ra...
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/adba59 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849394270090297344 |
|---|---|
| author | Apurba Bera Clancy W. James Mark M. McKinnon Ronald D. Ekers Tyson Dial Adam T. Deller Keith W. Bannister Marcin Glowacki Ryan M. Shannon |
| author_facet | Apurba Bera Clancy W. James Mark M. McKinnon Ronald D. Ekers Tyson Dial Adam T. Deller Keith W. Bannister Marcin Glowacki Ryan M. Shannon |
| author_sort | Apurba Bera |
| collection | DOAJ |
| description | Fast radio bursts (FRBs) are highly energetic events of short-duration intense radio emission, the origin of which remains elusive. Polarization of the FRB signals carries information about the emission source as well as the magnetoionic media the signal passes through before reaching terrestrial radio telescopes. Currently known FRBs show a diverse range of polarization, sometimes with complex features, making it challenging to describe them in a unified model. FRB 20230708A and FRB 20210912A are two bright and highly polarized (apparently) one-off FRBs detected in the Commensal Real-time ASKAP Fast Transients survey with the Australian Square Kilometre Array Pathfinder (ASKAP) that exhibit time-dependent conversion between linear and circular polarizations as well as intraburst (apparent) variation of the Faraday rotation measure. We investigate the intraburst temporal evolution of the polarization state of radio emission in these two events using the Poincaré sphere representation and find that the trajectories of the polarization state are well described by great circles on the Poincaré sphere. These polarization features may be signatures of a transition between two partially coherent orthogonal polarization modes or propagation through a birefringent medium. We find that the observed variations of the polarization states of these two FRBs are qualitatively consistent with a magnetospheric origin of the bursts and the effects of propagation through a birefringent medium with linearly polarized modes located close to the emission source—likely in the outer magnetosphere or near-wind region of a neutron star. |
| format | Article |
| id | doaj-art-232de5b105fb4f3bab38a2c08c1f0dbe |
| 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-232de5b105fb4f3bab38a2c08c1f0dbe2025-08-20T03:40:02ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01982211910.3847/1538-4357/adba59Unusual Intraburst Variations of Polarization States in FRB 20210912A and FRB 20230708A: Effects of Plasma Birefringence?Apurba Bera0https://orcid.org/0000-0002-2864-4110Clancy W. James1https://orcid.org/0000-0002-6437-6176Mark M. McKinnon2https://orcid.org/0009-0009-7038-1295Ronald D. Ekers3https://orcid.org/0000-0002-3532-9928Tyson Dial4https://orcid.org/0009-0004-1205-8805Adam T. Deller5https://orcid.org/0000-0001-9434-3837Keith W. Bannister6https://orcid.org/0000-0003-2149-0363Marcin Glowacki7https://orcid.org/0000-0002-5067-8894Ryan M. Shannon8https://orcid.org/0000-0002-7285-6348International Centre for Radio Astronomy Research, Curtin University , Bentley, WA 6102, Australia ; apurba.bera@curtin.edu.au, clancy.james@curtin.edu.auInternational Centre for Radio Astronomy Research, Curtin University , Bentley, WA 6102, Australia ; apurba.bera@curtin.edu.au, clancy.james@curtin.edu.auNational Radio Astronomy Observatory , Socorro, NM 87801, USA ; mmckinno@nrao.eduInternational Centre for Radio Astronomy Research, Curtin University , Bentley, WA 6102, Australia ; apurba.bera@curtin.edu.au, clancy.james@curtin.edu.au; Australia Telescope National Facility , CSIRO, Space and Astronomy, PO Box 76, Epping, NSW 1710, AustraliaCentre for Astrophysics and Supercomputing, Swinburne University of Technology , Hawthorn, VIC 3122, AustraliaCentre for Astrophysics and Supercomputing, Swinburne University of Technology , Hawthorn, VIC 3122, Australia; OzGrav , the ARC Centre of Excellence for Gravitational Wave Discovery, AustraliaAustralia Telescope National Facility , CSIRO, Space and Astronomy, PO Box 76, Epping, NSW 1710, Australia; Sydney Institute for Astronomy, School of Physics, The University of Sydney , NSW 2006, AustraliaInternational Centre for Radio Astronomy Research, Curtin University , Bentley, WA 6102, Australia ; apurba.bera@curtin.edu.au, clancy.james@curtin.edu.auCentre for Astrophysics and Supercomputing, Swinburne University of Technology , Hawthorn, VIC 3122, AustraliaFast radio bursts (FRBs) are highly energetic events of short-duration intense radio emission, the origin of which remains elusive. Polarization of the FRB signals carries information about the emission source as well as the magnetoionic media the signal passes through before reaching terrestrial radio telescopes. Currently known FRBs show a diverse range of polarization, sometimes with complex features, making it challenging to describe them in a unified model. FRB 20230708A and FRB 20210912A are two bright and highly polarized (apparently) one-off FRBs detected in the Commensal Real-time ASKAP Fast Transients survey with the Australian Square Kilometre Array Pathfinder (ASKAP) that exhibit time-dependent conversion between linear and circular polarizations as well as intraburst (apparent) variation of the Faraday rotation measure. We investigate the intraburst temporal evolution of the polarization state of radio emission in these two events using the Poincaré sphere representation and find that the trajectories of the polarization state are well described by great circles on the Poincaré sphere. These polarization features may be signatures of a transition between two partially coherent orthogonal polarization modes or propagation through a birefringent medium. We find that the observed variations of the polarization states of these two FRBs are qualitatively consistent with a magnetospheric origin of the bursts and the effects of propagation through a birefringent medium with linearly polarized modes located close to the emission source—likely in the outer magnetosphere or near-wind region of a neutron star.https://doi.org/10.3847/1538-4357/adba59Time domain astronomyRadio transient sourcesRadio bursts |
| spellingShingle | Apurba Bera Clancy W. James Mark M. McKinnon Ronald D. Ekers Tyson Dial Adam T. Deller Keith W. Bannister Marcin Glowacki Ryan M. Shannon Unusual Intraburst Variations of Polarization States in FRB 20210912A and FRB 20230708A: Effects of Plasma Birefringence? The Astrophysical Journal Time domain astronomy Radio transient sources Radio bursts |
| title | Unusual Intraburst Variations of Polarization States in FRB 20210912A and FRB 20230708A: Effects of Plasma Birefringence? |
| title_full | Unusual Intraburst Variations of Polarization States in FRB 20210912A and FRB 20230708A: Effects of Plasma Birefringence? |
| title_fullStr | Unusual Intraburst Variations of Polarization States in FRB 20210912A and FRB 20230708A: Effects of Plasma Birefringence? |
| title_full_unstemmed | Unusual Intraburst Variations of Polarization States in FRB 20210912A and FRB 20230708A: Effects of Plasma Birefringence? |
| title_short | Unusual Intraburst Variations of Polarization States in FRB 20210912A and FRB 20230708A: Effects of Plasma Birefringence? |
| title_sort | unusual intraburst variations of polarization states in frb 20210912a and frb 20230708a effects of plasma birefringence |
| topic | Time domain astronomy Radio transient sources Radio bursts |
| url | https://doi.org/10.3847/1538-4357/adba59 |
| work_keys_str_mv | AT apurbabera unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence AT clancywjames unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence AT markmmckinnon unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence AT ronalddekers unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence AT tysondial unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence AT adamtdeller unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence AT keithwbannister unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence AT marcinglowacki unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence AT ryanmshannon unusualintraburstvariationsofpolarizationstatesinfrb20210912aandfrb20230708aeffectsofplasmabirefringence |