Open AccessAnalysis of the thin layer of Galactic warm ionized gas in the range
Author(s) -
Paladini R.,
De Zotti G.,
Davies R. D.,
Giard M.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09160.x
Subject(s) - physics , spectral index , astrophysics , synchrotron radiation , ionization , spectral line , thermal , optics , astronomy , ion , quantum mechanics , meteorology
We present an analysis of the thin layer of Galactic warm ionized gas at an angular resolution ∼10 arcmin. This is carried out using radio continuum data at 1.4, 2.7 and 5 GHz in the coordinate region . For this purpose, we evaluate the zero level of the 2.7‐ and 5‐GHz surveys using auxiliary data at 2.3 GHz and 408 MHz. The derived zero‐level corrections are T zero (2.7 GHz) = 0.15 ± 0.06 K and T zero (5 GHz) = 0.1 ± 0.05 K . We separate the thermal (free–free) and non‐thermal (synchrotron) component by means of a spectral analysis performed adopting an antenna temperature spectral index −2.1 for the free–free emission, a realistic spatial distribution of indices for the synchrotron radiation and by fitting, pixel‐by‐pixel, the Galactic spectral index. We find that at 5 GHz, for | b | = 0° , the fraction of thermal emission reaches a maximum value of 82 per cent, while at 1.4 GHz, the corresponding value is 68 per cent. In addition, for the thermal emission, the analysis indicates a dominant contribution of the diffuse component relative to the source component associated with discrete H ii regions.