Faraday tomography with CHIME: the `tadpole' feature G137+7
Fuente:
arXiv
Guardado en:
| Autores principales: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
|---|---|
| Formato: | Preprint |
| Publicado: |
2024
|
| Materias: | |
| Acceso en línea: | |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| _version_ | 1866916342044557312 |
|---|---|
| author | Mohammed, Nasser Ordog, Anna Booth, Rebecca A. Bracco, Andrea Brown, Jo-Anne C. Carretti, Ettore Dickey, John M. Foreman, Simon Halpern, Mark Haverkorn, Marijke Hill, Alex S. Hinshaw, Gary Kania, Joseph W Kothes, Roland Landecker, T. L. MacEachern, Joshua Masui, Kiyoshi W. Menard, Aimee Ransom, Ryan R. Reich, Wolfgang Reich, Patricia Shaw, J. Richard Siegel, Seth R. Tahani, Mehrnoosh Thomson, Alec J. M. Pinsonneault-Marotte, Tristan Wang, Haochen West, Jennifer L. Wolleben, Maik Wulf, Dallas |
| author_facet | Mohammed, Nasser Ordog, Anna Booth, Rebecca A. Bracco, Andrea Brown, Jo-Anne C. Carretti, Ettore Dickey, John M. Foreman, Simon Halpern, Mark Haverkorn, Marijke Hill, Alex S. Hinshaw, Gary Kania, Joseph W Kothes, Roland Landecker, T. L. MacEachern, Joshua Masui, Kiyoshi W. Menard, Aimee Ransom, Ryan R. Reich, Wolfgang Reich, Patricia Shaw, J. Richard Siegel, Seth R. Tahani, Mehrnoosh Thomson, Alec J. M. Pinsonneault-Marotte, Tristan Wang, Haochen West, Jennifer L. Wolleben, Maik Wulf, Dallas |
| contents | A direct consequence of Faraday rotation is that the polarized radio sky does not resemble the total intensity sky at long wavelengths. We analyze G137+7, which is undetectable in total intensity but appears as a depolarization feature. We use the first polarization maps from the Canadian Hydrogen Intensity Mapping Experiment. Our $400-729$ MHz bandwidth and angular resolution, $17'$ to $30'$, allow us to use Faraday synthesis to analyze the polarization structure. In polarized intensity and polarization angle maps, we find a "tail" extending $10^\circ$ from the "head" and designate the combined object the "tadpole". Similar polarization angles, distinct from the background, indicate that the head and tail are physically associated. The head appears as a depolarized ring in single channels, but wideband observations show that it is a Faraday rotation feature. Our investigations of H I and H$α$ find no connections to the tadpole. The tail suggests motion of either the gas or an ionizing star through the ISM; the B2(e) star HD 20336 is a candidate. While the head features a coherent, $\sim -8$ rad m$^2$ Faraday depth, Faraday synthesis also identifies multiple components in both the head and tail. We verify the locations of the components in the spectra using QU fitting. Our results show that $\sim$octave-bandwidth Faraday rotation observations at $\sim 600$ MHz are sensitive to low-density ionized or partially-ionized gas which is undetectable in other tracers. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_15678 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Faraday tomography with CHIME: the `tadpole' feature G137+7 Mohammed, Nasser Ordog, Anna Booth, Rebecca A. Bracco, Andrea Brown, Jo-Anne C. Carretti, Ettore Dickey, John M. Foreman, Simon Halpern, Mark Haverkorn, Marijke Hill, Alex S. Hinshaw, Gary Kania, Joseph W Kothes, Roland Landecker, T. L. MacEachern, Joshua Masui, Kiyoshi W. Menard, Aimee Ransom, Ryan R. Reich, Wolfgang Reich, Patricia Shaw, J. Richard Siegel, Seth R. Tahani, Mehrnoosh Thomson, Alec J. M. Pinsonneault-Marotte, Tristan Wang, Haochen West, Jennifer L. Wolleben, Maik Wulf, Dallas Astrophysics of Galaxies A direct consequence of Faraday rotation is that the polarized radio sky does not resemble the total intensity sky at long wavelengths. We analyze G137+7, which is undetectable in total intensity but appears as a depolarization feature. We use the first polarization maps from the Canadian Hydrogen Intensity Mapping Experiment. Our $400-729$ MHz bandwidth and angular resolution, $17'$ to $30'$, allow us to use Faraday synthesis to analyze the polarization structure. In polarized intensity and polarization angle maps, we find a "tail" extending $10^\circ$ from the "head" and designate the combined object the "tadpole". Similar polarization angles, distinct from the background, indicate that the head and tail are physically associated. The head appears as a depolarized ring in single channels, but wideband observations show that it is a Faraday rotation feature. Our investigations of H I and H$α$ find no connections to the tadpole. The tail suggests motion of either the gas or an ionizing star through the ISM; the B2(e) star HD 20336 is a candidate. While the head features a coherent, $\sim -8$ rad m$^2$ Faraday depth, Faraday synthesis also identifies multiple components in both the head and tail. We verify the locations of the components in the spectra using QU fitting. Our results show that $\sim$octave-bandwidth Faraday rotation observations at $\sim 600$ MHz are sensitive to low-density ionized or partially-ionized gas which is undetectable in other tracers. |
| title | Faraday tomography with CHIME: the `tadpole' feature G137+7 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2405.15678 |