J/A+A/588/A97 Continuum sources from the THOR survey (Bihr+, 2016)
Continuum sources from the THOR survey between 1 and 2GHz.
Bihr S., Johnston K.G., Beuther H., Anderson L.D., Ott M.Rugel J.,
Bigiel F., Brunthaler A., Glover S.C.O., Henning T., Heyer M.H.,
Klessen R.S., Linz H., Longmore S.N., McClure-Griffiths N.M., Menten K.M.,
Plume R., Schierhuber T., Shanahan R., Stil J.M., Urquhart J.S., Walsh A.J.
<Astron. Astrophys. 588, A97 (2016)>
=2016A&A...588A..97B 2016A&A...588A..97B (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Radio continuum ; Milky Way
Keywords: catalogs - surveys - radio continuum: general -
techniques: interferometric
Abstract:
We carried out a large program with the Karl G. Jansky Very Large
Array (VLA): "THOR: The HI, OH, Recombination line survey of the Milky
Way". We observed a significant portion of the Galactic plane in the
first quadrant of the Milky Way in the 21cm HI line, 4 OH transitions,
19 radio recombination lines, and continuum from 1 to 2GHz. In this
paper we present a catalog of the continuum sources in the first half
of the survey (l=14.0-37.9° and l=47.1-51.2°, |b|<1.1°) at
a spatial resolution of 10-25", depending on the frequency and sky
position with a spatially varying noise level of ∼0.3-1mJy/beam.
The catalog contains ∼4400 sources. Around 1200 of these are spatially
resolved, and ∼1000 are possible artifacts, given their low
signal-to-noise ratios. Since the spatial distribution of the
unresolved objects is evenly distributed and not confined to the
Galactic plane, most of them are extragalactic. Thanks to the broad
bandwidth of the observations from 1 to 2GHz, we are able to determine
a reliable spectral index for ∼1800 sources. The spectral index
distribution reveals a double-peaked profile with maxima at spectral
indices of alpha=-1 and alpha=0, corresponding to steep declining
and flat spectra, respectively. This allows us to distinguish between
thermal and non-thermal emission, which can be used to determine the
nature of each source. We examine the spectral index of ∼300 known HII
regions, for which we find thermal emission with spectral indices
around alpha=0. In contrast, supernova remnants (SNR) show non-thermal
emission with alpha=-0.5 and extragalactic objects generally have a
steeper spectral index of alpha=-1.
Using the spectral index information of the THOR survey, we
investigate potential SNR candidates. We classify the radiation of
four SNR candidates as non-thermal, and for the first time, we provide
strong evidence for the SNR origin of these candidates.
Description:
The table includes all sources explained in the abstract.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 225 4422 Table containing all sources (table C1)
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See also:
J/A+A/580/A112 : THOR. The HI, OH, Recombination Line Survey (Bihr+, 2015)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- GName Name of the source (GLL.lll+B.bbb)
16- 23 F8.4 deg RAdeg Right ascension in J2000 of the peak position
26- 33 F8.4 deg DEdeg Declination in J2000 of the peak position
36- 42 F7.5 Jy Sp Peak intensity of average image used for
source extraction (Jy/beam) (1)
45- 50 F6.2 --- SNR Signal-to-noise ratio in the averaged image
53- 61 F9.5 Jy Sint Integrated flux density of the averaged
image (1)
64- 67 F4.1 arcsec BMAJ Major axis of the resolution element used for
the source extraction
70- 73 F4.1 arcsec BMIN Minor axis of the resolution element used for
the source extraction
76- 81 F6.1 deg BPA Rotation angle of the resolution element used
for the source extraction
84- 88 I5 --- Npix Number of pixels flooded by BLOBCAT
91 I1 --- res [0/1] Resolved source label.
1 = True, 0 = False.
94 I1 --- art [0/1] Label for possible artifacts and/
or SNR<7. 1 = True, 0 = False.
97-104 F8.5 Jy Sp1060 Peak intensity around 1.06GHz used for
spectral index (Jy/beam) (2)
107-113 F7.5 Jy e_Sp1060 Uncertainty of Sp1060 (Jy/beam) (2)
116-123 F8.5 Jy Sp1310 Peak intensity around 1.31GHz used for
spectral index (Jy/beam) (2)
126-132 F7.5 Jy e_Sp1310 Uncertainty of Sp1.31 (Jy/beam) (2)
135-142 F8.5 Jy Sp1440 Peak intensity around 1.44GHz used for
spectral index (Jy/beam) (2)
145-151 F7.5 Jy e_Sp1440 Uncertainty of Sp1.44 (Jy/beam) (2)
154-161 F8.5 Jy Sp1690 Peak intensity around 1.69GHz used for
spectral index (Jy/beam) (2)
164-170 F7.5 Jy e_Sp1690 Uncertainty of Sp1.69 (Jy/beam) (2)
173-180 F8.5 Jy Sp1820 Peak intensity around 1.82GHz used for
spectral index (Jy/beam) (2)
183-189 F7.5 Jy e_Sp1820 Uncertainty of Sp1.82 (Jy/beam) (2)
192-199 F8.5 Jy Sp1950 ?=- Peak intensity around 1.95GHz used for
spectral index (Jy/beam) (2)
202-208 F7.5 Jy e_Sp1950 ?=- Uncertainty of Sp1.95 (Jy/beam) (2)
211-216 F6.2 --- alpha Spectral index of source using all available
data points
219-222 F4.2 --- e_alpha Uncertainty of spectral index
225 I1 --- q_alpha [0/1] Label for reliable spectral index
1 = True, 0 = False
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Note (1): Synthesized beam is different for different fields.
Note (2): Synthesized beam is smoothed to 25"x25".
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Acknowledgements:
Simon Bihr, bihr(at)mpia.de
(End) S. Bihr [Max Planck Institute for Astronomy], P. Vannier [CDS] 12-Jan-2016