First detection of Circular Polarization in radio continuum towards a Massive Protostar
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866909677429719040 |
|---|---|
| author | Cheriyan, A. G. Vig, S. Roy, Nirupam Mandal, Samir Carrasco-González, C. Rodríguez-Kamenetzky, A. Pasetto, A. |
| author_facet | Cheriyan, A. G. Vig, S. Roy, Nirupam Mandal, Samir Carrasco-González, C. Rodríguez-Kamenetzky, A. Pasetto, A. |
| contents | Polarization measurements provide strong constraints on magnetic fields in star-forming systems. While magnetic field estimates of a few kiloGauss (kG) have been obtained near the surface of low-mass protostars, there are no analogous measurements in the immediate vicinity of the surface of massive protostars. We report the measurement of radio continuum circular polarization (CP) towards a massive protostar IRAS 18162-2048 for the first time wielding Karl G. Jansky Very Large Array (VLA) observations. The fractional CP varies between $3-5\%$ across the observed frequency range of $4-6$ GHz. We consider multiple hypotheses for the production of CP and propose (i) gyrosynchrotron emission and (ii) Faraday conversion due to turbulence in the magnetic medium - both driven by mildly relativistic electrons as plausible mechanisms. We estimate, for the first time, a magnetic field $B\gtrsim20-35$ G close to the massive protostar. The Lorentz factor of the low energy electrons is estimated to be in the range $γ_{min}\sim5-7$ for gyrosynchrotron emission and $80-100$ for Faraday conversion from our observations. The magnetic field estimate can provide important constraints to the formation models of massive stars. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_04913 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | First detection of Circular Polarization in radio continuum towards a Massive Protostar Cheriyan, A. G. Vig, S. Roy, Nirupam Mandal, Samir Carrasco-González, C. Rodríguez-Kamenetzky, A. Pasetto, A. Astrophysics of Galaxies Solar and Stellar Astrophysics Polarization measurements provide strong constraints on magnetic fields in star-forming systems. While magnetic field estimates of a few kiloGauss (kG) have been obtained near the surface of low-mass protostars, there are no analogous measurements in the immediate vicinity of the surface of massive protostars. We report the measurement of radio continuum circular polarization (CP) towards a massive protostar IRAS 18162-2048 for the first time wielding Karl G. Jansky Very Large Array (VLA) observations. The fractional CP varies between $3-5\%$ across the observed frequency range of $4-6$ GHz. We consider multiple hypotheses for the production of CP and propose (i) gyrosynchrotron emission and (ii) Faraday conversion due to turbulence in the magnetic medium - both driven by mildly relativistic electrons as plausible mechanisms. We estimate, for the first time, a magnetic field $B\gtrsim20-35$ G close to the massive protostar. The Lorentz factor of the low energy electrons is estimated to be in the range $γ_{min}\sim5-7$ for gyrosynchrotron emission and $80-100$ for Faraday conversion from our observations. The magnetic field estimate can provide important constraints to the formation models of massive stars. |
| title | First detection of Circular Polarization in radio continuum towards a Massive Protostar |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2507.04913 |