Polarimetric Properties of Blazars Caught by the WEBT
Active galactic nuclei come in many varieties. A minority of them are radio-loud, and exhibit two opposite prominent plasma jets extending from the proximity of the supermassive black hole up to megaparsec distances. When one of the relativistic jets is oriented closely to the line of sight, its emi...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-06-01
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| Series: | Galaxies |
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| Online Access: | https://www.mdpi.com/2075-4434/9/2/42 |
| _version_ | 1797530508694913024 |
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| author | Claudia M. Raiteri Massimo Villata |
| author_facet | Claudia M. Raiteri Massimo Villata |
| author_sort | Claudia M. Raiteri |
| collection | DOAJ |
| description | Active galactic nuclei come in many varieties. A minority of them are radio-loud, and exhibit two opposite prominent plasma jets extending from the proximity of the supermassive black hole up to megaparsec distances. When one of the relativistic jets is oriented closely to the line of sight, its emission is Doppler beamed and these objects show extreme variability properties at all wavelengths. These are called “blazars”. The unpredictable blazar variability, occurring on a continuous range of time-scales, from minutes to years, is most effectively investigated in a multi-wavelength context. Ground-based and space observations together contribute to give us a comprehensive picture of the blazar emission properties from the radio to the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>γ</mi></semantics></math></inline-formula>-ray band. Moreover, in recent years, a lot of effort has been devoted to the observation and analysis of the blazar polarimetric radio and optical behaviour, showing strong variability of both the polarisation degree and angle. The Whole Earth Blazar Telescope (WEBT) Collaboration, involving many tens of astronomers all around the globe, has been monitoring several blazars since 1997. The results of the corresponding data analysis have contributed to the understanding of the blazar phenomenon, particularly stressing the viability of a geometrical interpretation of the blazar variability. We review here the most significant polarimetric results achieved in the WEBT studies. |
| first_indexed | 2024-03-10T10:29:59Z |
| format | Article |
| id | doaj.art-1a64f03ae4e44f0c83675132135afbbd |
| institution | Directory Open Access Journal |
| issn | 2075-4434 |
| language | English |
| last_indexed | 2024-03-10T10:29:59Z |
| publishDate | 2021-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Galaxies |
| spelling | doaj.art-1a64f03ae4e44f0c83675132135afbbd2023-11-21T23:41:16ZengMDPI AGGalaxies2075-44342021-06-01924210.3390/galaxies9020042Polarimetric Properties of Blazars Caught by the WEBTClaudia M. Raiteri0Massimo Villata1INAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese, ItalyINAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese, ItalyActive galactic nuclei come in many varieties. A minority of them are radio-loud, and exhibit two opposite prominent plasma jets extending from the proximity of the supermassive black hole up to megaparsec distances. When one of the relativistic jets is oriented closely to the line of sight, its emission is Doppler beamed and these objects show extreme variability properties at all wavelengths. These are called “blazars”. The unpredictable blazar variability, occurring on a continuous range of time-scales, from minutes to years, is most effectively investigated in a multi-wavelength context. Ground-based and space observations together contribute to give us a comprehensive picture of the blazar emission properties from the radio to the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>γ</mi></semantics></math></inline-formula>-ray band. Moreover, in recent years, a lot of effort has been devoted to the observation and analysis of the blazar polarimetric radio and optical behaviour, showing strong variability of both the polarisation degree and angle. The Whole Earth Blazar Telescope (WEBT) Collaboration, involving many tens of astronomers all around the globe, has been monitoring several blazars since 1997. The results of the corresponding data analysis have contributed to the understanding of the blazar phenomenon, particularly stressing the viability of a geometrical interpretation of the blazar variability. We review here the most significant polarimetric results achieved in the WEBT studies.https://www.mdpi.com/2075-4434/9/2/42active galactic nucleiblazarsjetspolarimetry |
| spellingShingle | Claudia M. Raiteri Massimo Villata Polarimetric Properties of Blazars Caught by the WEBT Galaxies active galactic nuclei blazars jets polarimetry |
| title | Polarimetric Properties of Blazars Caught by the WEBT |
| title_full | Polarimetric Properties of Blazars Caught by the WEBT |
| title_fullStr | Polarimetric Properties of Blazars Caught by the WEBT |
| title_full_unstemmed | Polarimetric Properties of Blazars Caught by the WEBT |
| title_short | Polarimetric Properties of Blazars Caught by the WEBT |
| title_sort | polarimetric properties of blazars caught by the webt |
| topic | active galactic nuclei blazars jets polarimetry |
| url | https://www.mdpi.com/2075-4434/9/2/42 |
| work_keys_str_mv | AT claudiamraiteri polarimetricpropertiesofblazarscaughtbythewebt AT massimovillata polarimetricpropertiesofblazarscaughtbythewebt |