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A NEW OPTICAL POLARIZATION CATALOG FOR THE SMALL MAGELLANIC CLOUD: THE MAGNETIC FIELD STRUCTURE

Texto completo
Autor(es):
Gomes, Aiara Lobo [1, 2] ; Magalhaes, Antonio Mario [2] ; Pereyra, Antonio [3] ; Rodrigues, Claudia Vilega [4]
Número total de Autores: 4
Afiliação do(s) autor(es):
[1] Max Planck Inst Astron, D-69117 Heidelberg - Germany
[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo, SP - Brazil
[3] Inst Geofis Peru, Area Astron, Lima - Peru
[4] Inst Nacl Pesquisas Espaciais, BR-12227010 Sao Jose Dos Campos, SP - Brazil
Número total de Afiliações: 4
Tipo de documento: Artigo Científico
Fonte: ASTROPHYSICAL JOURNAL; v. 806, n. 1 JUN 10 2015.
Citações Web of Science: 3
Resumo

We present a new optical polarimetric catalog for the Small Magellanic Cloud (SMC). It contains a total of 7207 stars, located in the northeast (NE) and Wing sections of the SMC and part of the Magellanic Bridge. This new catalog is a significant improvement compared to previous polarimetric catalogs for the SMC. We used it to study the sky-projected interstellar magnetic field structure of the SMC. Three trends were observed for the ordered magnetic field direction at position angles (PAs) of (65 degrees +/- 10 degrees), (115 degrees +/- 10 degrees), and (150 degrees +/- 10 degrees). Our results suggest the existence of an ordered magnetic field aligned with the Magellanic Bridge direction and SMC's Bar in the NE region, which have PAs roughly at 115 degrees.4 and 45 degrees, respectively. However, the overall magnetic field structure is fairly complex. The trends at 115 degrees and 150 degrees may be correlated with the SMC's bimodal structure, observed in Cepheids' distances and HI velocities. We derived a value of B-sky = (0.947 +/- 0.079) mu G for the ordered sky-projected magnetic field, and delta B = (1.465 +/- 0.069) mu G for the turbulent magnetic field. This estimate of B-sky is significantly larger (by a factor of similar to 10) than the line of sight field derived from Faraday rotation observations, suggesting that most of the ordered field component is on the plane of the sky. A turbulent magnetic field stronger than the ordered field agrees with observed estimates for other irregular and spiral galaxies. For the SMC the B-sky/delta B ratio is closer to what is observed for our Galaxy than other irregular dwarf galaxies. (AU)

Processo FAPESP: 10/19694-4 - SOUTH POL: descobrindo o céu Austral polarizado
Beneficiário:Antônio Mário Magalhães
Linha de fomento: Auxílio à Pesquisa - Regular
Processo FAPESP: 10/03802-2 - A estrutura do campo magnético da Pequena Nuvem de Magalhães
Beneficiário:Aiara Lobo Gomes
Linha de fomento: Bolsas no Brasil - Mestrado
Processo FAPESP: 01/12589-1 - Stars, the interstellar medium and their interrelationships
Beneficiário:Antônio Mário Magalhães
Linha de fomento: Auxílio à Pesquisa - Temático