J/MNRAS/473/1685 Weak Galactic radio sources spectral indices (Cavallaro+, 2018)
SCORPIO - II. Spectral indices of weak Galactic radio sources.
Cavallaro F., Trigilio C., Umana G., Franzen T.M.O., Norris R.P., Leto P.,
Ingallinera A., Buemi C.S., Marvil J., Agliozzo C., Bufano F.,
Cerrigone L., Riggi S.
<Mon. Not. R. Astron. Soc., 473, 1685-1694 (2018)>
=2018MNRAS.473.1685C 2018MNRAS.473.1685C (SIMBAD/NED BibCode)
ADC_Keywords: Galactic plane ; Radio sources ; Interferometry
Keywords: techniques: interferometric - Galaxy: stellar content -
radio continuum: galaxies - radio continuum: ISM -
radio continuum: stars
Abstract:
In the next few years the classification of radio sources observed by
the large surveys will be a challenging problem and spectral index is
a powerful tool for addressing it. Here we present an algorithm to
estimate the spectral index of sources from multiwavelength radio
images. We have applied our algorithm to SCORPIO, a Galactic plane
survey centred around 2.1GHz carried out with Australian Telescope
Compact Array and found we can measure reliable spectral indices only
for sources stronger than 40 times the rms noise. Above a threshold of
1mJy, the source density in SCORPIO is 20 per cent greater than in
a typical extragalactic field, like Australia Telescope Large Area
Survey because of the presence of Galactic sources. Among this excess
population, 16 sources per square degree have a spectral index of
about zero suggesting optically thin thermal emission such as HII
regions and planetary nebulae, while 12 per square degree present a
rising spectrum, suggesting optically thick thermal emission such as
stars and UCHII regions.
Description:
The observations were performed in the periods 2011 April 21-24 and
2012 June 3-11, using ATCA in 6A and 6B configurations at 16-cm. The
field was observed using a mosaic of 38 pointings. A detailed
description of the observations and data reduction is reported in
Paper I, Umana et al., 2015MNRAS.454..902U 2015MNRAS.454..902U, Cat. J/MNRAS/454/902.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 54 499 Spectral indices catalogue
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See also:
J/MNRAS/454/902 : SCORPIO 1 catalogue of compact radio sources (Umana+, 2015)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- --- [SCORPIO1_]
10- 13 A4 --- Scorpio1 Scorpio1 designation (NNNa)
15- 22 F8.4 deg GLON Galactic longitude
24- 30 F7.4 deg GLAT Galactic latitude
32- 37 F6.2 mJy S2.1GHz Flux density at 2.1GHz
39- 43 F5.2 mJy e_S2.1GHz rms uncertainty on flux density at 2.1GHz
45- 49 F5.2 --- alpha Spectral index
51- 54 F4.2 --- e_alpha rms uncertainty on alpha
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History:
From electronic version of the journal
References:
Umana et al., Paper I 2015MNRAS.454..902U 2015MNRAS.454..902U, Cat. J/MNRAS/454/902
(End) Patricia Vannier [CDS] 06-Aug-2020