- ID:
- ivo://CDS.VizieR/J/MNRAS/373/1531
- Title:
- 6C** sample of steep-spectrum radio sources
- Short Name:
- J/MNRAS/373/1531
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present basic observational data on the 6C** sample. This is a new sample of radio sources drawn from the 151-MHz 6C survey, which was filtered with radio criteria chosen to optimize the chances of finding radio galaxies at z>4. The filtering criteria are a steep-spectral index and a small angular size. The final sample consists of 68 sources from a region of sky covering 0.421sr. We present Very Large Array radio maps, and the results of K-band imaging and optical spectroscopy.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/375/1349
- Title:
- 6C** sample of steep-spectrum radio sources. II
- Short Name:
- J/MNRAS/375/1349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the 6C** sample to investigate the comoving space density of powerful, steep-spectrum radio sources. This sample, consisting of 68 objects, has virtually complete K-band photometry and spectroscopic redshifts for 32 per cent of the sources. In order to find its complete redshift distribution, we develop a method of redshift estimation based on the Kz diagram of the 3CRR, 6CE, 6C* and 7CRS radio galaxies. Based on this method, we derive redshift probability density functions for all the optically identified sources in the 6C** sample. Using a combination of spectroscopic and estimated redshifts, we select the most radio luminous sources in the sample. Their redshift distribution is then compared with the predictions of the radio luminosity function of Jarvis et al. (2001MNRAS.327..907J). We find that, within the uncertainties associated with the estimation method, the data are consistent with a constant comoving space density of steep-spectrum radio sources beyond z>2.5, and rule out a steep decline.
- ID:
- ivo://CDS.VizieR/J/ApJ/463/205
- Title:
- CS and NH3 Survey of H2O Maser Emission
- Short Name:
- J/ApJ/463/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CS J=1-0 and NH(J,K)=(1,1) observations toward a large sample of H2O maser regions are reported. A total of 172 sources were observed. 107 were observed in CS and 164 in NH_3_. The main purpose of this work was to study the relationship between the parameters that characterize the high velocity H2O maser emission, which originates in very small (about 10 AU) and very dense (10^7-10^9/cm^3^) regions, and those that characterize the molecular emission coming from quiescent, more extended (0.1-1.0 pc) high density (10^4-10^5/cm^3^) regions, traced by the CS and NH_3_ emissions. The observations were carried out between 1986 and 1990 with the 37 m radio telescope at Haystack Observatory The emission of the (J,K)=(1,1) inversion transition of the NH_3_ molecule at 23.694496 GHz, and the emission of the J=1->0 rotational transition of the CS molecule at 48.990968 GHz were observed.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A222
- Title:
- CS isotopes towards Galactic centre clouds
- Short Name:
- J/A+A/642/A222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measuring isotopic ratios is a sensitive technique to obtain information on stellar nucleosynthesis and chemical evolution. We present measurements of the carbon and sulphur abundances in the interstellar medium of the central region of our Galaxy. The selected targets are the +50km/s Cloud and several line-of-sight clouds towards Sgr B2(N). Towards the +50km/s Cloud, we observed the J=2-1 rotational transitions of ^12^C^32^S, ^12^C^34^S, ^13^C^32^S, ^12^C^33^S, and ^13^C^34^S, and the J=3-2 transitions of ^12^C^32^S and ^12^C^34^S with the IRAM-30m telescope, as well as the J=6-5 transitions of ^12^C^34^S and ^13^C^32^S with the APEX 12m telescope, all in emission. The J=2-1 rotational transitions of ^12^C^32^S, ^12^C^34^S, ^13^C^32^S, and ^13^C^34^S were observed with ALMA in Sgr B2(N)'s envelope, with those of ^12^C^32^S and ^12^C^34^S also observed in the line-of-sight clouds towards Sgr B2(N), all in absorption. In the +50km/s Cloud, we derive a ^12^C/^13^C isotopic ratio of 22.1^+3.3^_-2.4_, that leads, with the measured ^13^C^32^S/^12^C^34^S line intensity ratio, to a ^32^S/^34^S ratio of 16.3^+3.0^_-2.4_. We have also derived the ^32^S/^34^S isotopic ratio more directly from the two isotopologues ^13^C^32^S and ^13^C^34^S, which leads to an independent ^32^S/^34^S estimation of 16.3^+2.1^_-1.7_ and 17.9+/-5.0 for the +50km/s Cloud and Sgr B2(N), respectively. We also obtain a ^34^S/^33^S ratio of 4.3+/-0.2 in the +50km/s Cloud. Previous studies observed a decreasing trend in the ^32^S/^34^S isotopic ratios when approaching the Galactic centre. Our result indicates a termination of this tendency at least at a galactocentric distance of 130^+60^_-30_pc. This is at variance with findings based on ^12^C/^13^C, ^14^N/^15^N and ^18^O/^17^O isotope ratios, where the above-mentioned trend is observed to continue right to the central molecular zone. This can indicate a drop in the production of massive stars at the Galactic centre, in the same line as recent metallicity gradient ([Fe/H]) studies, and opens the work towards a comparison with Galactic and stellar evolution models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/3786
- Title:
- CSS and GPS radio sources sample
- Short Name:
- J/MNRAS/458/3786
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The dependence of the turnover frequency on the linear size is presented for a sample of Giga-hertz Peaked Spectrum and Compact Steep Spectrum radio sources derived from complete samples. The dependence of the luminosity of the emission at the peak frequency with the linear size and the peak frequency is also presented for the galaxies in the sample. The luminosity of the smaller sources evolve strongly with the linear size. Optical depth effects have been included to the 3D model for the radio source of Kaiser to study the spectral turnover. Using this model, the observed trend can be explained by synchrotron self-absorption. The observed trend in the peak-frequency-linear-size plane is not affected by the luminosity evolution of the sources.
- ID:
- ivo://CDS.VizieR/J/A+A/369/380
- Title:
- CSS/GPS radio sources VLA observations
- Short Name:
- J/A+A/369/380
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 98 Compact Steep-Spectrum and GHz-Peaked Spectrum (CSS-GPS) candidates from the B3-VLA sample has been observed with the VLA (A configuration) at 8.5, 4.9 and 1.5 GHz, with resolutions of 0.2, 0.4 and 1.4 arcsec, in total intensity and polarization. Source positions, flux densities, polarization parameters, angular sizes and spectral information are reported for the confirmed CSS (Table 3) and the non-CSS (Table 3bis) sources.
387. 9C survey at 15GHz
- ID:
- ivo://CDS.VizieR/J/MNRAS/342/915
- Title:
- 9C survey at 15GHz
- Short Name:
- J/MNRAS/342/915
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fields chosen for the first observations of the cosmic microwave background with the Very Small Array have been surveyed with the Ryle Telescope at 15GHz. We have covered three regions around RA=00h20m DE=+30{deg}, RA=09h40m DE=+32{deg} and RA=15h40m DE=+43{deg} (J2000.0), an area of 520{deg}^2^. There are 242 sources above the estimated completeness limit of ~25mJy, although a total of ~760 sources have been detected, some as faint as 10mJy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/200/747
- Title:
- 5C12: survey near the North Galactic Pole
- Short Name:
- J/MNRAS/200/747
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains a deep survey (5C12) of a region close to the North Galactic Pole carried out with the Cambridge One-Mile Telescope at 408 MHz (HPBW 80"x139") and at 1407 MHz (HPBW 23"x40"). The flux densities are on the KPW scale (Kellermann et al. 1969ApJ...157....1K), and were based on 3C48, 3C147 and 3C295. This part of the survey contains 321 sources with apparent flux densities brighter than 9 mJy at 408 MHz or 1.4 mJy at 1407 MHz.
- ID:
- ivo://CDS.VizieR/J/A+AS/110/419
- Title:
- 7C: survey of radio sources
- Short Name:
- J/A+AS/110/419
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cambridge Low Frequency Synthesis Telescope has been used at 151MHz to survey a region of 418 square degrees centred at RA=17h, DE=65deg, which includes the North Ecliptic Cap. The resolution is 70x70"cosec{delta} and the rms noise on the maps is 25mJy/beam. We present positions and flux densities for 2702 sources which have a signal to noise ratio >5.5 and radio maps of 37 selected extended sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/2708
- Title:
- 10C survey of radio sources at 15.7GHz
- Short Name:
- J/MNRAS/415/2708
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a previous paper (Paper I, Franzen et al., 2011MNRAS.415.2699F), the observational, mapping and source-extraction techniques used for the Tenth Cambridge (10C) Survey of Radio Sources were described. Here, the first results from the survey, carried out using the Arcminute Microkelvin Imager Large Array (LA) at an observing frequency of 15.7GHz, are presented. The survey fields cover an area of ~27deg^2^ to a flux-density completeness of 1mJy. Results for some deeper areas, covering ~12deg^2^, wholly contained within the total areas and complete to 0.5mJy, are also presented. The completeness for both areas is estimated to be at least 93 per cent. The 10C survey is the deepest radio survey of any significant extent (>~0.2deg^2^) above 1.4GHz.