[{"abstract":[{"text":"Radiative corrections of quantum electrodynamics cause a vacuum threaded by a magnetic field to be birefringent. This means that radiation of different polarizations travels at different speeds. Even in the strong magnetic fields of astrophysical sources, the difference in speed is small. However, it has profound consequences for the extent of polarization expected from strongly magnetized sources. We demonstrate how the birefringence arises from first principles, show how birefringence affects the polarization state of radiation and present recent calculations for the expected polarization from magnetars and X-ray pulsars.","lang":"eng"}],"oa":1,"_id":"15235","day":"21","language":[{"iso":"eng"}],"oa_version":"Published Version","main_file_link":[{"url":"https://doi.org/10.3390/galaxies6030076","open_access":"1"}],"publication_status":"published","doi":"10.3390/galaxies6030076","article_type":"original","article_number":"76","article_processing_charge":"No","issue":"3","status":"public","date_created":"2024-03-26T10:38:46Z","title":"Strongly magnetized sources: QED and X-ray polarization","publisher":"MDPI","arxiv":1,"external_id":{"arxiv":["1802.00358"]},"citation":{"short":"J. Heyl, I. Caiazzo, Galaxies 6 (2018).","apa":"Heyl, J., &#38; Caiazzo, I. (2018). Strongly magnetized sources: QED and X-ray polarization. <i>Galaxies</i>. MDPI. <a href=\"https://doi.org/10.3390/galaxies6030076\">https://doi.org/10.3390/galaxies6030076</a>","chicago":"Heyl, Jeremy, and Ilaria Caiazzo. “Strongly Magnetized Sources: QED and X-Ray Polarization.” <i>Galaxies</i>. MDPI, 2018. <a href=\"https://doi.org/10.3390/galaxies6030076\">https://doi.org/10.3390/galaxies6030076</a>.","ieee":"J. Heyl and I. Caiazzo, “Strongly magnetized sources: QED and X-ray polarization,” <i>Galaxies</i>, vol. 6, no. 3. MDPI, 2018.","ista":"Heyl J, Caiazzo I. 2018. Strongly magnetized sources: QED and X-ray polarization. Galaxies. 6(3), 76.","mla":"Heyl, Jeremy, and Ilaria Caiazzo. “Strongly Magnetized Sources: QED and X-Ray Polarization.” <i>Galaxies</i>, vol. 6, no. 3, 76, MDPI, 2018, doi:<a href=\"https://doi.org/10.3390/galaxies6030076\">10.3390/galaxies6030076</a>.","ama":"Heyl J, Caiazzo I. Strongly magnetized sources: QED and X-ray polarization. <i>Galaxies</i>. 2018;6(3). doi:<a href=\"https://doi.org/10.3390/galaxies6030076\">10.3390/galaxies6030076</a>"},"date_updated":"2024-04-08T07:02:25Z","type":"journal_article","year":"2018","keyword":["Astronomy and Astrophysics"],"scopus_import":"1","tmp":{"image":"/images/cc_by.png","short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"extern":"1","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","quality_controlled":"1","month":"07","date_published":"2018-07-21T00:00:00Z","author":[{"last_name":"Heyl","full_name":"Heyl, Jeremy","first_name":"Jeremy"},{"id":"8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d","first_name":"Ilaria","orcid":"0000-0002-4770-5388","full_name":"Caiazzo, Ilaria","last_name":"Caiazzo"}],"volume":6,"intvolume":"         6","publication":"Galaxies","publication_identifier":{"eissn":["2075-4434"]}},{"publication":"Galaxies","publication_identifier":{"eissn":["2075-4434"]},"date_published":"2018-05-24T00:00:00Z","author":[{"last_name":"Caiazzo","full_name":"Caiazzo, Ilaria","orcid":"0000-0002-4770-5388","first_name":"Ilaria","id":"8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d"},{"last_name":"Heyl","full_name":"Heyl, Jeremy","first_name":"Jeremy"}],"intvolume":"         6","volume":6,"keyword":["Astronomy and Astrophysics"],"tmp":{"image":"/images/cc_by.png","short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"scopus_import":"1","extern":"1","month":"05","quality_controlled":"1","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","arxiv":1,"publisher":"MDPI","date_updated":"2024-10-14T12:33:20Z","external_id":{"arxiv":["1805.11018"]},"citation":{"apa":"Caiazzo, I., &#38; Heyl, J. (2018). Probing black hole magnetic fields with QED. <i>Galaxies</i>. MDPI. <a href=\"https://doi.org/10.3390/galaxies6020057\">https://doi.org/10.3390/galaxies6020057</a>","short":"I. Caiazzo, J. Heyl, Galaxies 6 (2018).","ama":"Caiazzo I, Heyl J. Probing black hole magnetic fields with QED. <i>Galaxies</i>. 2018;6(2). doi:<a href=\"https://doi.org/10.3390/galaxies6020057\">10.3390/galaxies6020057</a>","mla":"Caiazzo, Ilaria, and Jeremy Heyl. “Probing Black Hole Magnetic Fields with QED.” <i>Galaxies</i>, vol. 6, no. 2, 57, MDPI, 2018, doi:<a href=\"https://doi.org/10.3390/galaxies6020057\">10.3390/galaxies6020057</a>.","ieee":"I. Caiazzo and J. Heyl, “Probing black hole magnetic fields with QED,” <i>Galaxies</i>, vol. 6, no. 2. MDPI, 2018.","ista":"Caiazzo I, Heyl J. 2018. Probing black hole magnetic fields with QED. Galaxies. 6(2), 57.","chicago":"Caiazzo, Ilaria, and Jeremy Heyl. “Probing Black Hole Magnetic Fields with QED.” <i>Galaxies</i>. MDPI, 2018. <a href=\"https://doi.org/10.3390/galaxies6020057\">https://doi.org/10.3390/galaxies6020057</a>."},"year":"2018","type":"journal_article","title":"Probing black hole magnetic fields with QED","date_created":"2024-03-26T10:39:26Z","status":"public","issue":"2","article_type":"original","article_processing_charge":"No","article_number":"57","main_file_link":[{"open_access":"1","url":"https://doi.org/10.3390/galaxies6020057"}],"publication_status":"published","doi":"10.3390/galaxies6020057","abstract":[{"text":"The effect of vacuum birefringence is one of the first predictions of quantum electrodynamics (QED): the presence of a charged Dirac field makes the vacuum birefringent when threaded by magnetic fields. This effect, extremely weak for terrestrial magnetic fields, becomes important for highly magnetized astrophysical objects, such as accreting black holes. In the X-ray regime, the polarization of photons traveling in the magnetosphere of a black hole is not frozen at emission but is changed by the local magnetic field. We show that, for photons traveling along the plane of the disk, where the field is expected to be partially organized, this results in a depolarization of the X-ray radiation. Because the amount of depolarization depends on the strength of the magnetic field, this effect can provide a way to probe the magnetic field in black-hole accretion disks and to study the role of magnetic fields in astrophysical accretion in general.","lang":"eng"}],"oa":1,"_id":"15237","oa_version":"Published Version","day":"24","language":[{"iso":"eng"}]}]