TY - JOUR
T1 - Continuum sources from the THOR survey between 1 and 2 GHz
AU - Bihr, S.
AU - Johnston, K. G.
AU - Beuther, H.
AU - Anderson, L. D.
AU - Ott, J.
AU - Rugel, M.
AU - Bigiel, F.
AU - Brunthaler, A.
AU - Glover, S. C.O.
AU - Henning, T.
AU - Heyer, M. H.
AU - Klessen, R. S.
AU - Linz, H.
AU - Longmore, S. N.
AU - McClure-Griffiths, N. M.
AU - Menten, K. M.
AU - Plume, R.
AU - Schierhuber, T.
AU - Shanahan, R.
AU - Stil, J. M.
AU - Urquhart, J. S.
AU - Walsh, A. J.
N1 - Publisher Copyright:
© 2016 ESO.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - We carried out a large program with the Karl G. Jansky Very Large Array (VLA): "THOR: The H1, OH, Recombination line survey of the Milky Way". We observed a significant portion (~100 deg2) of the Galactic plane in the first quadrant of the Milky Way in the 21 cm H I line, 4 OH transitions, 19 radio recombination lines, and continuum from 1 to 2 GHz. 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 ~0.3.1 mJy beam-1. The catalog contains ~4400 sources. Around 1200 of these are spatially resolved, and ~1000 are possible artifacts, given their low signaltonoise 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 2 GHz, we are able to determine a reliable spectral index for ~1800 sources. The spectral index distribution reveals a doublepeaked profile with maxima at spectral indices of a ≈-1 and a ≈ 0, corresponding to steep declining and flat spectra, respectively. This allows us to distinguish between thermal and nonthermal 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 a≈ 0. In contrast, supernova remnants (SNR) show nonthermal emission with a ≈-0.5 and extragalactic objects generally have a steeper spectral index of a ≈-1. Using the spectral index information of the THOR survey, we investigate potential SNR candidates. We classify the radiation of four SNR candidates as nonthermal, and for the first time, we provide strong evidence for the SNR origin of these candidates.
AB - We carried out a large program with the Karl G. Jansky Very Large Array (VLA): "THOR: The H1, OH, Recombination line survey of the Milky Way". We observed a significant portion (~100 deg2) of the Galactic plane in the first quadrant of the Milky Way in the 21 cm H I line, 4 OH transitions, 19 radio recombination lines, and continuum from 1 to 2 GHz. 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 ~0.3.1 mJy beam-1. The catalog contains ~4400 sources. Around 1200 of these are spatially resolved, and ~1000 are possible artifacts, given their low signaltonoise 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 2 GHz, we are able to determine a reliable spectral index for ~1800 sources. The spectral index distribution reveals a doublepeaked profile with maxima at spectral indices of a ≈-1 and a ≈ 0, corresponding to steep declining and flat spectra, respectively. This allows us to distinguish between thermal and nonthermal 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 a≈ 0. In contrast, supernova remnants (SNR) show nonthermal emission with a ≈-0.5 and extragalactic objects generally have a steeper spectral index of a ≈-1. Using the spectral index information of the THOR survey, we investigate potential SNR candidates. We classify the radiation of four SNR candidates as nonthermal, and for the first time, we provide strong evidence for the SNR origin of these candidates.
KW - Catalogs
KW - Radio continuum: general
KW - Surveys
KW - Techniques: interferometric
UR - http://www.scopus.com/inward/record.url?scp=84962700459&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201527697
DO - 10.1051/0004-6361/201527697
M3 - Article
SN - 0004-6361
VL - 588
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A97
ER -