The University of Michigan Centimeter-Band All Stokes Blazar Monitoring Program: Single-Dish Polarimetry as a Probe of Parsec-Scale Magnetic Fields
The University of Michigan 26-m paraboloid was dedicated to obtaining linear polarization and total flux density observations of blazars from the mid-1960s until June 2012, providing an unprecedented record tracking centimeter-band variability over decades at 14.5, 8.0, and 4.8 GHz for both targeted...
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| Format: | Article |
| Language: | English |
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MDPI AG
2017-11-01
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| Series: | Galaxies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2075-4434/5/4/75 |
| _version_ | 1818491510529720320 |
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| author | Margo F. Aller Hugh D. Aller Philip A. Hughes |
| author_facet | Margo F. Aller Hugh D. Aller Philip A. Hughes |
| author_sort | Margo F. Aller |
| collection | DOAJ |
| description | The University of Michigan 26-m paraboloid was dedicated to obtaining linear polarization and total flux density observations of blazars from the mid-1960s until June 2012, providing an unprecedented record tracking centimeter-band variability over decades at 14.5, 8.0, and 4.8 GHz for both targeted objects and members of flux-limited samples. In the mid-1970s through the mid-1980s, and during the last decade of the program, observations were additionally obtained of circular polarization for a small sample of radio-bright (S > 5 Jy), active sources. Key program results include evidence supporting class-dependent differences in the magnetic field geometry of BL Lac and QSO jets, identification of linear polarization changes temporally associated with flux outbursts supporting a shock-in-jet scenario, and determination of the spectral evolution of the Stokes V amplitude and polarity for testing proposed models. Recent radiative transfer modeling during large flares supports a jet scenario with a kinetically-dominated, relativistic flow at parsec scales with embedded turbulent magnetic fields and dynamically-weak ordered components which may be helical; the circular polarization observations are consistent with linear-to-circular mode conversion within this turbulent jet environment. |
| first_indexed | 2024-12-10T17:31:59Z |
| format | Article |
| id | doaj.art-7f06f781e9214a928b5b0a0f0fa8d484 |
| institution | Directory Open Access Journal |
| issn | 2075-4434 |
| language | English |
| last_indexed | 2024-12-10T17:31:59Z |
| publishDate | 2017-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Galaxies |
| spelling | doaj.art-7f06f781e9214a928b5b0a0f0fa8d4842022-12-22T01:39:39ZengMDPI AGGalaxies2075-44342017-11-01547510.3390/galaxies5040075galaxies5040075The University of Michigan Centimeter-Band All Stokes Blazar Monitoring Program: Single-Dish Polarimetry as a Probe of Parsec-Scale Magnetic FieldsMargo F. Aller0Hugh D. Aller1Philip A. Hughes2Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1107, USADepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109-1107, USADepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109-1107, USAThe University of Michigan 26-m paraboloid was dedicated to obtaining linear polarization and total flux density observations of blazars from the mid-1960s until June 2012, providing an unprecedented record tracking centimeter-band variability over decades at 14.5, 8.0, and 4.8 GHz for both targeted objects and members of flux-limited samples. In the mid-1970s through the mid-1980s, and during the last decade of the program, observations were additionally obtained of circular polarization for a small sample of radio-bright (S > 5 Jy), active sources. Key program results include evidence supporting class-dependent differences in the magnetic field geometry of BL Lac and QSO jets, identification of linear polarization changes temporally associated with flux outbursts supporting a shock-in-jet scenario, and determination of the spectral evolution of the Stokes V amplitude and polarity for testing proposed models. Recent radiative transfer modeling during large flares supports a jet scenario with a kinetically-dominated, relativistic flow at parsec scales with embedded turbulent magnetic fields and dynamically-weak ordered components which may be helical; the circular polarization observations are consistent with linear-to-circular mode conversion within this turbulent jet environment.https://www.mdpi.com/2075-4434/5/4/75blazarslinear polarizationcentimeter-bandmagnetic fields |
| spellingShingle | Margo F. Aller Hugh D. Aller Philip A. Hughes The University of Michigan Centimeter-Band All Stokes Blazar Monitoring Program: Single-Dish Polarimetry as a Probe of Parsec-Scale Magnetic Fields Galaxies blazars linear polarization centimeter-band magnetic fields |
| title | The University of Michigan Centimeter-Band All Stokes Blazar Monitoring Program: Single-Dish Polarimetry as a Probe of Parsec-Scale Magnetic Fields |
| title_full | The University of Michigan Centimeter-Band All Stokes Blazar Monitoring Program: Single-Dish Polarimetry as a Probe of Parsec-Scale Magnetic Fields |
| title_fullStr | The University of Michigan Centimeter-Band All Stokes Blazar Monitoring Program: Single-Dish Polarimetry as a Probe of Parsec-Scale Magnetic Fields |
| title_full_unstemmed | The University of Michigan Centimeter-Band All Stokes Blazar Monitoring Program: Single-Dish Polarimetry as a Probe of Parsec-Scale Magnetic Fields |
| title_short | The University of Michigan Centimeter-Band All Stokes Blazar Monitoring Program: Single-Dish Polarimetry as a Probe of Parsec-Scale Magnetic Fields |
| title_sort | university of michigan centimeter band all stokes blazar monitoring program single dish polarimetry as a probe of parsec scale magnetic fields |
| topic | blazars linear polarization centimeter-band magnetic fields |
| url | https://www.mdpi.com/2075-4434/5/4/75 |
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