J/MNRAS/448/3731 Local Group dSph radio survey with ATCA (Regis+, 2015) ================================================================================ Local Group dSph radio survey with ATCA - I: observations and background sources. Regis M., Richter L., Colafrancesco S., Massardi M., De Blok W.J.G., Profumo S., Orford N. =2015MNRAS.448.3731R (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Galaxies, nearby ; Radio sources Keywords: catalogues - galaxies: dwarf - radio continuum: galaxies Abstract: Dwarf spheroidal (dSph) galaxies are key objects in near-field cosmology, especially in connection to the study of galaxy formation and evolution at small scales. In addition, dSphs are optimal targets to investigate the nature of dark matter. However, while we begin to have deep optical photometric observations of the stellar population in these objects, little is known so far about their diffuse emission at any observing frequency, and hence on thermal and non-thermal plasma possibly residing within dSphs. In this paper, we present deep radio observations of six local dSphs performed with the Australia Telescope Compact Array (ATCA) at 16cm wavelength. We mosaicked a region of radius of about 1{deg} around three 'classical' dSphs, Carina, Fornax, and Sculptor, and of about half of degree around three 'ultrafaint' dSphs, BootesII, Segue2, and Hercules. The rms noise level is below 0.05 mJy for all the maps. The restoring beams full width at half-maximum ranged from 4.2"x2.5" to 30.0"x2.1" in the most elongated case. A catalogue including the 1392 sources detected in the six dSph fields is reported. The main properties of the background sources are discussed, with positions and fluxes of brightest objects compared with the FIRST, NVSS, and SUMSS observations of the same fields. The observed population of radio emitters in these fields is dominated by synchrotron sources. We compute the associated source number counts at 2GHz down to fluxes of 0.25mJy, which prove to be in agreement with AGN count models. Description: We present a catalogue of radio sources detected in the fields of six dwarf spheroidal galaxies of the Local Group, which are Carina, Fornax, Sculptor, BootesII, Segue2, and Hercules. Observations were performed during July/August 2011 with the six 22-m diameter Australia Telescope Compact Array antennae operating at 16cm wavelength. We mosaicked a region of radius of about one degree around the first three dwarfs, and of about half of degree around the last three dwarfs. The rms noise level is below 0.05mJy. The restoring beams FWHM ranged from 4.2x2.5-arcseconds to 30.0x2.1-arcseconds in the most elongated case. The catalogue includes different parameters describing 1835 entries which, in our classification, correspond to 1392 sources. See the publication for more details. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table4.dat 72 1834 Catalogue of radio sources in the fields of the dwarf spheroidal galaxies Carina, Fornax, Sculptor, Bootes II, Segue 2, and Hercules -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 I2 h RAh Right ascension (J2000) 4- 5 I2 min RAm Right ascension (J2000) 7- 10 F4.1 s RAs Right ascension (J2000) (1) 12 A1 --- DE- Declination sign (J2000) 13- 14 I2 deg DEd Declination (J2000) 16- 17 I2 arcmin DEm Declination (J2000) 19- 22 F4.1 arcsec DEs Declination (J2000) (1) 24- 29 F6.2 mJy Fp Peak flux density at 2GHz (un-tapered map) (2) 31- 36 F6.2 mJy Fint Integrated flux density at 2GHz (un-tapered map) 38- 42 F5.2 mJy e_Fint Error on integrated flux density (3) 44- 47 F4.2 arcmin bmaj FWHM major axis of the source (4) 49- 52 F4.2 arcmin bmin FWHM minor axis of the source (4) 54- 59 F6.2 deg PA [] Source position angle (north to east) (4) 61- 66 F6.2 deg Fgt Integrated flux density at 2GHz in the tapered map 68- 72 A5 --- MFlag Flag for multiple component sources (5) -------------------------------------------------------------------------------- Note (1): The positional uncertainty amounts to about 1 arcsec. Note (2): Peak flux densities are not corrected for possible systematic effects, which are estimated to be negligible (see discussion in the publication). Note (3): Errors on integrated flux density are obtained summing in quadrature the local rms, the fit error, and a 5% of the flux density (to account for possible inaccuracy in the calibration model and process, especially due to RFI). Note (4): When F/Fp<1.3, the source is not successfully deconvolved and these values should not be considered. Note (5): Flag for multiple component sources as follows: S = single component source M = multiple component source, followed by a number, identifying the multiple source to which the component belongs, and a letter identifying the field (a=Carina, b=Fornax, c=Sculptor, d=BootesII, e=Hercules, f=Segue2) * = Source present in the tapered map, but not in the un-tapered map. In this case, all the properties in the other columns are derived from the tapered map. -------------------------------------------------------------------------------- History: From electronic version of the journal Acknowledgements: Marco Regis, University of Turin and INFN, Italy References: Regis et al., Paper II 2015MNRAS.448.3747R ================================================================================ (End) Marco Regis [Turin Univ & INFN, Italy], Patricia Vannier [CDS] 17-Sep-2015