- ID:
- ivo://CDS.VizieR/J/A+A/658/A4
- Title:
- LOFAR imaging of Arp299 at 150MHz
- Short Name:
- J/A+A/658/A4
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the spatially resolved emission of Arp 299 revealed by 150 MHz international baseline Low-Frequency Array (LOFAR) and 1.4, 5.0, and 8.4GHz Very Large Array (VLA) observations. Nowadays, LOFAR allows to compare its resolution with the VLA ones. These will allow us to obtain pixel-by-pixel spectral imdex maps and local radio SEDs. With this information we recover the nature of the ISM around the main structures (either clumpy or continuous), as well as magnetic fields. The 150MHz image also shows structures never seen before, pointing out that these radio-frequencies observations are a perfect tool to detect them.
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- ID:
- ivo://CDS.VizieR/J/A+A/655/A40
- Title:
- LoLSS-Deep Bootes 54MHz catalog
- Short Name:
- J/A+A/655/A40
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the first sub-mJy (~0.7mJy/beam) survey to be completed below 100 MHz, which is over an order of magnitude deeper than previously achieved for widefield imaging of any field at these low frequencies. The high-resolution (15x15arcsec) image of the Bootes field at 34-75MHz is made from 56 hours of observation with the LOw Frequency ARray (LOFAR) Low Band Antenna (LBA) system. We present a radio source catalogue containing 1,948 sources detected over an area of 23.6 sq. deg, with a peak flux density threshold of 5{sigma}. Using the available deep 144-MHz data, we identified 144-MHz counterparts to all the 54-MHz sources, and produced a matched catalogue within the deep optical coverage area containing 829 sources.
- ID:
- ivo://CDS.VizieR/J/A+A/555/A23
- Title:
- M82-A radio continuum and polarisation study I.
- Short Name:
- J/A+A/555/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to study the cosmic ray propagation and determine the magnetic field strength and dominant loss processes in the nearby prototypical starbursting galaxy M82, a multi-frequency analysis at four radio wavelengths is presented. Archival data from the Westerbork Synthesis Radio Telescope (WSRT) was reduced and a new calibration technique introduced to reach the high dynamic ranges needed for the complex source morphology. These data were combined with archival Very Large Array (VLA) data, yielding total power maps at {lambda}3cm, {lambda}6cm, {lambda}22cm, and {lambda}92cm. The data show a confinement of the emission at wavelengths of {lambda}3/{lambda}6cm to the core region and a largely extended halo reaching up to 4kpc away from the galaxy midplane at wavelengths of {lambda}22/{lambda}92cm up to a sensitivity limit of 90uJy and 1.8mJy respectively indicating different physical processes in the core and halo regions. The results are used to calculate the magnetic field strength to 98uG in the core region and to 24uG in the halo regions. From the observation of ionisation losses, the filling factor of the ionised medium could be estimated to 2%. This leads to a revised view of the magnetic field distribution in the core region and the propagation processes from the core into the halo regions.
- ID:
- ivo://CDS.VizieR/J/A+A/651/A98
- Title:
- M31 C-band (6.6GHz) Sardinia radio tel. map
- Short Name:
- J/A+A/651/A98
- Date:
- 17 Jan 2022 11:45:00
- Publisher:
- CDS
- Description:
- The Andromeda galaxy is the best known large galaxy besides our own Milky Way. Several images and studies exist at all wavelengths from radio to hard X-ray. Nevertheless, only few observations are available in the microwave range where its average radio emission reaches the minimum. In this paper we want to study the radio morphology of the galaxy, decouple thermal from non-thermal emission and extract the star formation rate. We also aim to derive a complete catalogue of radio sources for the mapped patch of sky. We have observed the Andromeda galaxy with the Sardinia Radio Telescope at 6.6 GHz with very high sensitivity and angular resolution, and an unprecedented sky coverage. Using new 6.6GHz data and Effelsberg radio telescope ancillary data, we confirm that, globally, the spectral index assumes a value of ~0.7-0.8, while in the star forming regions it decreases to ~0.5. By disentangling (gas) thermal and non-thermal emission, we found that at 6.6GHz, thermal emission follows the distribution of HII regions around the ring. Non-thermal emission, within the ring, appears to be more uniform and smooth than thermal emission, due to the diffusion of the cosmic ray electrons away from their birthplaces. Hence the magnetic fields are nearly constant in intensity. Based on the thermal emission map, we have calculated a star formation rate map. Integrating within a radius of R_max_=15kpc, we obtained a total star formation rate of 0.19+/-0.01M*/yr in agreement with previous results in literature. Finally, we correlated our radio data with Infrared images of the Andromeda galaxy. We found an unexpected high correlation between non-thermal and MIR data in the central region, with a correlation parameter r=0.93. Finally, by computing the logarithmic 24um/21cm ratio q_24um_, we found a decreasing trend with increasing galactocentric distance and an increasing dispersion. The logarithmic FIR/radio ratio is found to be 2.41+/-0.04.
- ID:
- ivo://CDS.VizieR/VIII/98
- Title:
- 180MHz Murchison Commissioning Survey (MWACS)
- Short Name:
- VIII/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Murchison Widefield Array Commissioning Survey (MWACS) is a ~6100deg^2^ 104-196MHz radio sky survey performed with the Murchison Widefield Array during instrument commissioning between 2012 September and 2012 December. The data were taken as meridian drift scans with two different 32-antenna sub-arrays that were available during the commissioning period. The data were combined in the visibility plane before being imaged, and then mosaicked. The survey covers approximately 20.5h<RA<8.5h, -58{deg}<Dec<-14{deg} over three frequency bands centred on 119, 150 and 180MHz. The survey has 3arcmin angular resolution and a typical noise level of 40mJy/beam, with reduced sensitivity near the field boundaries and bright sources. The catalogue consists of flux density and spectral index measurements for 14,110 sources, extracted from the mosaics, 1,247 of which are sub-components of complexes of sources.
- ID:
- ivo://CDS.VizieR/J/A+AS/97/435
- Title:
- 1410MHz-spectra of quasars III.
- Short Name:
- J/A+AS/97/435
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third and final part of the research at 1410MHz for 213 extragalactic objects from the Southern Hemisphere identified as Quasars by Veron-Cetty and Veron (1983A&AS...53..219V). The first (1988A&AS...76...21Q) and second (1990A&AS...83..393Q) parts contained measurement of the flux densities at 1410MHz for 473 sources.
- ID:
- ivo://CDS.VizieR/VIII/29A
- Title:
- 1400-MHz Survey of 1478 Abell Clusters of Galaxies
- Short Name:
- VIII/29A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains observations of Abell clusters of galaxies which were obtained with the Green Bank 91-m telescope at 1400 MHz with an angular resolution of 10'x11' (RAxDEC). This catalog extends the sample of clusters originally published in Owen (1974AJ.....79..427O). The primary goals of this survey were to observe all Abell (1958ApJS....3..211A, Cat. VII/4) clusters with m10 (magnitude of the tenth brightest galaxy in the cluster) less than or equal to 17.0 and declinations north of -19 degrees, to observe all clusters with richness>=3 regardless of m10, and to obtain observations of a representative sample of the rest of the catalog (m10>=17.0; richness<=2). The abelclus.dat file contains ALL 957 detected sources (also beyond 0.5 corrected Abell radii). It contains 525 sources within 0.5 corrected Abell radii, while the published table1.dat file contains 487 entries corresponding to 485 distinct sources (in 442 clusters). The catalog entries contains the flux density at 1400 MHz, the Abell cluster number, richness class, distance class, m10, redshift estimate (z), corrected Abell cluster radius, right ascension (B1950), declination (B1950), deconvolved major and minor source axis lengths, position angle, and distance of the source from the cluster center.
- ID:
- ivo://CDS.VizieR/J/ApJS/103/331
- Title:
- mJy radio sources at 1.4 GHz
- Short Name:
- J/ApJS/103/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From the 1.4GHz radio survey of Condon, Dickey, & Salpeter (Cat. <J/AJ/99/1071>) in a region much devoid of rich galaxy clusters at redshifts z<0.43 we selected a "distant" sample of 57 radio sources complete to a 1.4GHz flux density of 35mJy and a "nearby" sample of 36 mostly weaker radio sources which are optically brighter than B~19mag. Our ultimate goals are (1) to study the radio, optical, and near-IR properties of those high-redshift (z~1), moderate-power radio sources in the distant sample and to compare them with that of more powerful radio sources, and (2) to make a comparison of primarily noncluster radio sources in the nearby sample with a companion survey of radio sources in a pair of rich superclusters at z~0.1. In this first paper of a series, we report our new C-array VLA continuum snapshots at 4.86GHz and optical R-band CCD imaging photometry for these two samples and tabulate the observational results on individual sources. Some direct sample statistical properties are also discussed in the paper and summarized as follows: (1) The distant sample: (a) The sample median flux density at 1.4GHz is about 65mJy. (b) The majority (80%) of the sample sources have a steep spectrum between 1.4 and 4.86GHz with a spectral index around 0.9. Nineteen (90%) of the 21 sources that are fully resolved at 4.86 GHz (i.e., angular sizes {theta}>11") have a radio morphology of Fanaroff-Riley (FR) II type. (c) Thirty-seven (88%) of the 42 optically imaged sample sources were optically identified to a limiting R-band magnitude of R~23.5mag. About 15% of the identified radio sources appear to be point sources, and the others are extended galaxies with an appearance similar to nearby elliptical galaxies. (d) Twenty-eight (76%) of the optically identified sources have R>20mag, suggesting that these are probably distant (z>0.8), with a redshift distribution peaking at z~1, where their radio luminosities are about 10 times the break power between the FR I and II classes. (e) We found no strong evidence for the radio and optical axes of the resolved radio sources (i.e., {theta}>5") to be correlated or anticorrelated, nor any evidence for strong clustering around sample radio sources on average. (2) The nearby sample: except for R<15, the sample is dominated by elliptical galaxies with 16<R<18.5mag and a spectral index distribution similar to that of the distant sample. Based on the radial distribution of optical objects around each radio source, we found that the average radio source environment becomes richer from that characteristic of galaxy groups for R<17mag (z<0.2) to that of galaxy groups to clusters at R>18mag (z>0.3) .
- ID:
- ivo://CDS.VizieR/J/ApJ/874/43
- Title:
- MOJAVE. XVII. Parsec-scale jet kinematics of AGNs
- Short Name:
- J/ApJ/874/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a parsec-scale jet kinematics study of 409 bright radio-loud active galactic nuclei (AGNs) based on 15GHz Very Long Baseline Array (VLBA) data obtained between 1994 August 31 and 2016 December 26 as part of the 2cm VLBA survey and Monitoring Of Jets in Active galactic nuclei with VLBA Experiments (MOJAVE) programs. We tracked 1744 individual bright features in 382 jets over at least 5 epochs. A majority (59%) of the best-sampled jet features showed evidence of accelerated motion at the >3{sigma} level. Although most features within a jet typically have speeds within ~40% of a characteristic median value, we identified 55 features in 42 jets that had unusually slow pattern speeds, nearly all of which lie within 4pc (100pc deprojected) of the core feature. Our results, combined with other speeds from the literature, indicate a strong correlation between apparent jet speed and synchrotron peak frequency, with the highest jet speeds being found only in low-peaked AGNs. Using Monte Carlo simulations, we find best-fit parent population parameters for a complete sample of 174 quasars above 1.5Jy at 15GHz. Acceptable fits are found with a jet population that has a simple unbeamed power-law luminosity function incorporating pure luminosity evolution and a power-law Lorentz factor distribution ranging from 1.25 to 50 with slope -1.4+/-0.2. The parent jets of the brightest radio quasars have a space density of 261+/-19Gpc^-3^ and unbeamed 15GHz luminosities above ~10^24.5^W/Hz, consistent with FRII class radio galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/484/119
- Title:
- Multi-epoch VLBI survey of CJF sources
- Short Name:
- J/A+A/484/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers presenting VLBI observations of the 293 Caltech-Jodrell Bank Flat-spectrum (hereafter CJF) sources and their analysis. We obtain a consistent motion dataset large enough to allow the systematic properties of the population to be studied. We present detailed kinematic analysis of the complete flux-density limited CJF survey. We computed 2-D kinematic models based on the optimal model-fitting parameters of multi-epoch VLBA observations. This allows us to calculate not only radial, but also orthogonal motions, and thus to study curvature and acceleration. Statistical tests of the motions measured and their reliability were performed. A correlation analysis between the derived apparent motions, luminosities, spectral indices, and core dominance and the resulting consequences is described. With at least one velocity in each of the 237 sources, this sample is much larger than any available before, so it allows a meaning ful statistical investigation of apparent motions and any possible correlations with other parameters in AGN jets. The main results to emerge are as follows: * In general motions are not consistent with a single uniform velocity applicable to all components along a jet. * We find a slight trend towards a positive outward acceleration and also adduce some evidence for greater acceleration in the innermost regions. * We find a lack of fast components at physical distances less than a few pc from the reference feature. * Only ~4% of the components from galaxies and <2% of those from quasars undergo large bends i.e. within 15{deg} of +/-90{deg}. * The distribution of radial velocities shows a broad distribution of velocities (apparent velocities up to 30c). Fifteen percent of the best-sampled jet components exhibit low velocities that may need to be explained in a different manner to the fast motions. * Some negative superluminal motions are seen, and in 15 cases (6%) these are definitely significant. * We find a strong correlation between the 5 GHz luminosity and the apparent velocity. * The CJF galaxies, on average, show slower apparent jet-component velocities than the quasars. * The mean velocity in the VLBA 2cm survey (Kellermann et al. 2004) is substantially higher than in the CJF survey, the ratio could be roughly a factor of 1.5-2. This supports the observed trend toward increasing apparent velocity with in creasing observing frequency. This AGN survey provides the basis for any statistical analysis of jet and jet-component properties.