Bibcode
Battistelli, E. S.; Carretti, E.; Cruciani, A.; de Bernardis, P.; Génova-Santos, R.; Masi, S.; Naldi, A.; Paladini, R.; Piacentini, F.; Tibbs, C. T.; Verstraete, L.; Ysard, N.
Referencia bibliográfica
The Astrophysical Journal, Volume 801, Issue 2, article id. 111, 15 pp. (2015).
Fecha de publicación:
3
2015
Revista
Número de citas
24
Número de citas referidas
23
Descripción
We have observed the H II region RCW175 with the 64 m Parkes telescope
at 8.4 GHz and 13.5 GHz in total intensity, and at 21.5 GHz in both
total intensity and polarization. High angular resolution ranging from 1
to 2.4 arcmin, high sensitivity, and polarization capability enable us
to perform a detailed study of the different constituents of the H II
region. For the first time, we resolve three distinct regions at
microwave frequencies, two of which are part of the same annular diffuse
structure. Our observations enable us to confirm the presence of
anomalous microwave emission (AME) from RCW175. Fitting the integrated
flux density across the entire region with the currently available
spinning dust models, using physically motivated assumptions, indicates
the presence of at least two spinning dust components: a warm component
(T gas = 5800 K) with a relatively large hydrogen number
density n H = 26.3/cm3 and a cold component (T
gas = 100 K) with a hydrogen number density of n H
= 150/cm3. The present study is an example highlighting the
potential of using high angular-resolution microwave data to break model
parameter degeneracies. Thanks to the spectral coverage and angular
resolution of the Parkes observations, we have been able to derive one
of the first AME/excess maps, at 13.5 GHz, showing clear evidence that
the bulk of the anomalous emission arises in particular from one of the
source components, with some additional contribution from the diffuse
structure. A cross-correlation analysis with thermal dust emission has
shown a high degree of correlation with one of the regions within
RCW175. In the center of RCW175, we find an average polarized emission
at 21.5 GHz of 2.2 ± 0.2(rand.) ± 0.3(sys.)% of the total
emission, where we have included both systematic and statistical
uncertainties at 68% CL. This polarized emission could be due to
sub-dominant synchrotron emission from the region and is thus consistent
with very faint or non-polarized emission associated with AME.
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