Por favor, use este identificador para citar o enlazar este ítem:
http://inaoe.repositorioinstitucional.mx/jspui/handle/1009/2224| OH Maser Sources in W49N: Probing Magnetic Field and Differential Anisotropic Scattering with Zeeman pairs using the VLBA | |
| Eduardo Mendoza Torres | |
| Acceso Abierto | |
| Atribución-NoComercial-SinDerivadas | |
| Masers ISM: molecules Magnetic fields Individual (W49N) Radio lines: ISM Structure function | |
| Our analysis of a VLBA 12-hour synthesis observation of the OH masers in awell-known star-forming region W49N has yielded valuable data that enables usto probe distributions of magnetic fields in both the maser columns and the inter-vening interstellar medium (ISM). The data consisting of detailed high angular-resolution images (with beam-width ∼20 milli-arc-seconds) of several dozen OH maser sources or spots, at 1612, 1665 and 1667 MHz, reveal anisotropic scatter broadening, with typical sizes of a few tens of milli-arc-seconds and axial ratios between 1.5 to 3. Such anisotropies have been reported earlier by Desai, Gwinn & Diamond (1994) and interpreted as induced by the local magnetic field parallel tothe Galactic plane. However, we find a) the apparent angular sizes on the averagea factor of about 2.5 less than those reported by Desai et al. (1994), indicating significantly less scattering than inferred earlier, and b) a significant deviation inthe average orientation of the scatter-broadened images (by ∼10 degrees) from that implied by the magnetic field in the Galactic plane. More intriguingly, for afew Zeeman pairs in our set, significant differences (up to 6σ) are apparent in thescatter broadened images for the two hands of circular polarization, even when apparent velocity separation is less than 0.1 km s⁻¹. This may possibly be the first example of a Faraday rotation contribution to the diffractive effects in the ISM. Using the Zeeman pairs, we also study the distribution of magnetic field inthe W49N complex, finding no significant trend in the spatial structure function.In this paper, we present the details of our observations and analysis leading tothese findings, discuss implications of our results for the intervening anisotropic magneto-ionic medium, and suggest the possible implications for the structure of magnetic fields within this star-forming region. | |
| The Astrophysical Journal | |
| 30-07-2013 | |
| Artículo | |
| Inglés | |
| Estudiantes Investigadores Público en general | |
| Deshpande, Avinash A., et al., (2013). OH Maser Sources in W49N: Probing Magnetic Field and Differential Anisotropic Scattering with Zeeman pairs using the VLBA, The Astrophysical Journal, Vol. 775(1):1-19 | |
| ASTRONOMÍA Y ASTROFÍSICA | |
| Versión aceptada | |
| acceptedVersion - Versión aceptada | |
| Aparece en las colecciones: | Artículos de Astrofísica |
Cargar archivos:
| Fichero | Tamaño | Formato | |
|---|---|---|---|
| 9. OH Maser Sources in W49N-Probing Magnetic Field and Differential Anisotropic Scattering with Zeeman Pairs Using the Very Long Baseline Array.pdf | 272.22 kB | Adobe PDF | Visualizar/Abrir |