Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/710/L58
- Title:
- Coronal type II radio bursts in 2002
- Short Name:
- J/ApJ/710/L58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Major space weather events such as solar flares and coronal mass ejections are usually accompanied by solar radio bursts, which can potentially be used for real-time space weather forecasts. Type II radio bursts are produced near the local plasma frequency and its harmonic by fast electrons accelerated by a shock wave moving through the corona and solar wind with a typical speed of ~1000km/s. The coronal bursts have dynamic spectra with frequency gradually falling with time and durations of several minutes. This Letter presents a new method developed to detect type II coronal radio bursts automatically and describes its implementation in an extended Automated Radio Burst Identification System (ARBIS 2). Preliminary tests of the method with spectra obtained in 2002 show that the performance of the current implementation is quite high, ~80%, while the probability of false positives is reasonably low, with one false positive per 100-200hr for high solar activity and less than one false event per 10000hr for low solar activity periods. The first automatically detected coronal type II radio burst is also presented.
- ID:
- ivo://CDS.VizieR/J/ApJS/203/15
- Title:
- Counterparts to 1.4GHz sources in ECDF-S
- Short Name:
- J/ApJS/203/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study a sample of 883 sources detected in a deep Very Large Array survey at 1.4GHz in the Extended Chandra Deep Field South. This paper focuses on the identification of their optical and infrared (IR) counterparts. We use a likelihood-ratio technique that is particularly useful when dealing with deep optical images to minimize the number of spurious associations. We find a reliable counterpart for 95% of our radio sources. Most of the counterparts (74%) are detected at optical wavelengths, but there is a significant fraction (21%) that are only detectable in the IR. Combining newly acquired optical spectra with data from the literature, we are able to assign a redshift to 81% of the identified radio sources (37% spectroscopic). We also investigate the X-ray properties of the radio sources using the Chandra 4Ms and 250ks observations. In particular, we use a stacking technique to derive the average properties of radio objects undetected in the Chandra images. The results of our analysis are collected in a new catalog containing the position of the optical/IR counterpart, the redshift information, and the X-ray fluxes. It is the deepest multi-wavelength catalog of radio sources, which will be used for future study of this galaxy population.
- ID:
- ivo://CDS.VizieR/J/ApJ/405/498
- Title:
- Counts and spectral indices at 8.44GHz
- Short Name:
- J/ApJ/405/498
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the VLA to make deep images of two 7x7' fields at 8.44 GHz with 10" resolution. With an rms noise of 3.2 and 5.1 {micro}Jy, respectively, in the two fields, we compiled a catalog of 82 sources. The normalized differential 8.44 GHz counts are similar to those at 1.41 and 4.86 GHz. All show a similarly steep submillijansky slope, which is only somewhat flatter than that expected for a nonevolving Euclidean population ({gamma}=2.5). Microjansky radio sources at 4.86 GHz have been identified with faint blue galaxies (18<~V<~28 mag). We argue that their expected median redshift is about 0.5-0.75. Hence, cosmological evolution may be needed to explain the steep slope of the microjansky counts. The 8.44 GHz counts must converge with slope {gamma}<2.0 below S(8.44)~300 nJy, or they would exceed the available field galaxy counts down to V~28 mag, and they must permanently converge below S(8.44)~20 nJy, or their integrated sky brightness would distort the observed thermal cosmic background radiation spectrum at centimeter wavelengths. The estimated 31.5 GHz sky brightness from nanojansky to jansky levels is <36 {micro}K (3{sigma}). Even if weak radio sources cluster on scales of degrees as faint galaxies do, their anisotropic contribution to the COBE DMR experiment (with 7deg FWHM-beam) would not exceed ~1.2{micro}K.
- ID:
- ivo://CDS.VizieR/J/MNRAS/410/2690
- Title:
- CRATES sources at 30 GHz
- Short Name:
- J/MNRAS/410/2690
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Knowledge of the population of radio sources in the range ~2-200GHz is important for understanding their effects on measurements of the cosmic microwave background power spectrum. We report measurements of the 30-GHz flux densities of 605 radio sources from the Combined Radio All-sky Targeted Eight-GHz Survey (CRATES), which have been made with the One Centimetre Receiver Array-prototype (OCRA-p) on the Torun 32-m telescope. The flux densities of sources that were also observed by Wilkinson Microwave Anisotropy Probe (WMAP) and previous OCRA surveys are in broad agreement with those reported here, however a number of sources display intrinsic variability. We find a good correlation between the 30GHz and Fermi gamma-ray flux densities for common sources. We examine the radio spectra of all observed sources and report a number of gigahertz-peaked and inverted spectrum sources. These measurements will be useful for comparison to those from the Low Frequency Instrument of the Planck satellite, which will make some of its most sensitive observations in the region covered here.
- ID:
- ivo://CDS.VizieR/J/PASP/97/932
- Title:
- 3CR Source Identifications
- Short Name:
- J/PASP/97/932
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains the third major update of new optical and radio data for the strong sources in the Revised Third Cambridge Catalogue (3CR). Positions, redshifts, magnitudes, and identifications are included, as well as some radio data for 298 3CR sources.
- 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.
- 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/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.
