- ID:
- ivo://CDS.VizieR/J/A+A/575/A55
- Title:
- Radio jet emission from GeV-emitting NLSy1
- Short Name:
- J/A+A/575/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the current study we aim at gaining understanding on the properties of radio emission and the assumed jet from four radio loud and {gamma}-ray loud Narrow Line Seyfert 1 galaxies i.e. Seyfert 1 galaxies with emission lines at the low-end of the FWHM distribution. The ultimate goal is twofold; first, the investigation whether a relativistic jet is operating at the source giving out the radio output observed and second, the quantification of the jet characteristics in order to understand possible similarities and differences with the jets found in typical blazars. The current study relies on the most systematic monitoring of radio loud and {gamma}-ray detected Narrow Line Seyfert 1 galaxies in the cm and mm radio bands conducted with the Effelsberg 100-m and IRAM 30-m telescopes. It covers the longest time baselines and the most radio frequencies, to date. This dataset of multi- wavelength, long-term radio light curves is analysed from a number of perspectives. A novel algorithm is introduced in order to extract sensible variability parameters (mainly amplitudes and timescales) which are then used for the computation of variability brightness temperatures and the corresponding Doppler factors. The jet powers are computed from the light curves to estimate the energy output and compare it with typical blazars. The dynamics of radio Spectra Energy Distributions are examined for understanding the mechanism causing the variability. The length of the available light curves for 3 of the 4 sources in the sample allowed a firm understanding of the general behaviour of the sources. They all display intensive variability which seems to be happening at a pace rather faster than what is generally seen in blazars. The flaring events become progressively more prominent as the frequency increases and show intensive spectral evolution indicative of shock evolution. The variability brightness temperatures and the associated Doppler factors are rather moderate implying a mildly relativistic jet. The computed jet powers show very energetic flows. The radio polarisation in one case, clearly implies the presence of a quiescent jet underlying recursive flaring activity. Finally, in one case, the sudden disappearance of a {gamma}-ray flare below some critical frequency in our band, urges for further investigation of the possible mechanism causing the evolution of broadband events. Despite the generally lower flux densities the sources appear to show all typical characteristics seen in blazars powered by relativistic jets. Intensive variability, spectral evolution across the different bands following evolutionary paths explained by traveling shocks, Doppler factors indicating mildly relativistic speeds.
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3022. Radio-loud AGN in SDSS
- ID:
- ivo://CDS.VizieR/J/MNRAS/362/9
- Title:
- Radio-loud AGN in SDSS
- Short Name:
- J/MNRAS/362/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 2712 radio-luminous galaxies is defined from the second data release of the Sloan Digital Sky Survey (SDSS) by cross-comparing the main spectroscopic galaxy sample with two radio surveys: the National Radio Astronomy Observatories (NRAO) Very Large Array (VLA) Sky Survey (NVSS, <VIII/65>) and the Faint Images of the Radio Sky at Twenty centimeters (FIRST, <VIII/71>) survey. The comparison is carried out in a multistage process and makes optimal use of both radio surveys by exploiting the sensitivity of the NVSS to extended and multicomponent radio sources in addition to the high angular resolution of the FIRST images. A radio source sample with 95 per cent completeness and 98.9% reliability is achieved, far better than would be possible for this sample if only one of the surveys was used. The radio source sample is then divided into two classes: radio-loud active galactic nuclei (AGN) and galaxies in which the radio emission is dominated by star formation. The division is based on the location of a galaxy in the plane of 4000{AA} break strength versus radio luminosity per unit stellar mass and provides a sample of 2215 radio-loud AGN and 497 star-forming galaxies brighter than 5mJy at 1.4GHz. A full catalogue of positions and radio properties is provided for these sources.
- ID:
- ivo://CDS.VizieR/J/A+A/363/141
- Title:
- Radio-loud galaxies in the ROSAT survey. IV.
- Short Name:
- J/A+A/363/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-frequency radio data for 741 extragalactic sources with a 5GHz integrated flux density of >100mJy. These sources have been selected from a cross-correlation of an early ROSAT All-Sky Survey source list with a list of compact radio sources of the 5GHz Green Bank northern sky survey (RGB sample, Cat. <VIII/52>). The majority of sources were quasi-simultaneously observed with the Effelsberg 100-m telescope at 11cm, 6cm, and 2.8cm. We have determined the spectrum, size and linear polarization properties of these sources. We compare the radio data with ROSAT measurements and optical data. We find that the X-ray selected radio sources, when compared with unbiased radio source samples, are on average slightly more compact, show a higher fractional polarization, a higher absolute rotation measure (RM), and have flatter spectra. Absolute RMs are larger for steep spectrum than for flat spectrum sources and for extended than for compact sources. The average redshift increases with the radio flux density, which indicates that the X-ray selected radio sources have a larger fraction of beamed radio emission. All source characteristics of the sample are in accordance with present unification schemes for AGN, where X-ray selected sources are preferably looked at face on.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A92
- Title:
- Radio-loud NLSy1 galaxies optical polarisation
- Short Name:
- J/A+A/618/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We quantify the temporal behaviour of the optical polarisation fraction and angle for a selected sample of radio-loud NLSy1s. We also search for rotations of the polarisation plane similar to those commonly observed in blazars. The dataset was obtained with the RoboPol polarimeter of the Skinakas observatory as well as the KANATA, Perkins, and Steward observatories. We carried out numerical simulations to assess the probability that long rotations of the polarisation plane were caused by intrinsically evolving electric vector position angles (EVPAs) instead of observational noise. We conclude that it is much more likely that intrinsic rotations are responsible for the observed phenomenology.
- ID:
- ivo://CDS.VizieR/J/MNRAS/390/289
- Title:
- Radio observations of A3158
- Short Name:
- J/MNRAS/390/289
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 1.4- and 2.5-GHz Australia Telescope Compact Array (ATCA) observations of the galaxy cluster A3158 (z=0.0597) which is located within the central part of the Horologium-Reticulum supercluster (HRS). Spectroscopic data for the central part of the HRS suggest that A3158 is in a dynamically important position within the supercluster and that it is moving toward the double cluster system A3125/A3128 which marks the centre of the HRS. A total of 110 radio galaxies are detected in a 35-arcmin radius about the cluster at 1.4GHz, of which 30 are also detected at 2.5GHz.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/288
- Title:
- Radio obs. of NGC 6251 jet
- Short Name:
- J/ApJ/833/288
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The structure of the NGC 6251 jet on the milliarcsecond scale is investigated using images taken with the European VLBI Network and the Very Long Baseline Array. We detect a structural transition of the jet from a parabolic to a conical shape at a distance of (1-2)x10^5^ times the Schwarzschild radius from the central engine, which is close to the sphere of gravitational influence of the supermassive black hole (SMBH). We also examine the jet pressure profiles with the synchrotron minimum energy assumption to discuss the physical origin of the structural transition. The NGC 6251 jet, together with the M87 jet, suggests a fundamental process of structural transition in the jets of active galactic nuclei (AGNs). Collimated AGN jets are characterized by their external galactic medium, showing that AGN jets interplay with the SMBH and its host galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/479
- Title:
- Radio obs. of optically obscured galaxies
- Short Name:
- J/MNRAS/383/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper analyses the radio properties of a subsample of optically obscured (R>=25.5) galaxies observed at 24um by the Spitzer Space Telescope within the First Look Survey. Ninety-six F24um>=0.35mJy objects out of 510 are found to have a radio counterpart at 1.4GHz, 610MHz or at both frequencies, respectively, down to ~40 and ~200uJy. IRAC photometry sets the majority of them in the redshift interval z~=[1-3] and allows for a broad distinction between active galactic nucleus (AGN) dominated galaxies (~47 per cent of the radio-identified sample) and systems powered by intense star formation (~13 per cent), the remaining objects being impossible to classify. The percentage of radio identifications is a strong function of 24-um flux: almost all sources brighter than F_24um_~2mJy are endowed with a radio flux at both 1.4GHz and 610MHz, while this fraction drastically decreases by lowering the 24-um flux level.
- ID:
- ivo://CDS.VizieR/J/ApJS/167/103
- Title:
- Radio/Optical catalog of the SSA 13 field
- Short Name:
- J/ApJS/167/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 1.4GHz catalog of 810 radio sources (560 sources in the complete sample) found in the SSA 13 field (RA=13:12, DE=42:38). The 1.4GHz radio image was obtained from a 91hr VLA integration with an rms noise level of 4.82uJy/beam at the field center. Optical images in the R band (6300{AA}) and z band (9200{AA}) with 3{sigma} detection magnitudes of 26.1 and 24.9, respectively, were obtained from three observing nights on the 8m Subaru Telescope. We find that 88%+/-2% of the radio sources are identified with an optical counterpart.
- ID:
- ivo://CDS.VizieR/J/A+A/379/21
- Title:
- Radio-optically selected galaxy clusters I.
- Short Name:
- J/A+A/379/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The radiosource catalogs have been extracted from 31 NRAO VLA Sky Survey maps (NVSS, Condon et al., 1988AJ....115.1693C) over approximately 550 square degrees of sky in the region of the South Galactic Pole. File table1.dat contains the catalog of 13340 pointlike sources. For each source are given: Right Ascension and Declination, source name (if applicable), peak flux, flux rms from the fit, error on source position as estimated by the fitting algorithm, x and y pixel of the position where the peak has been detected on the map (starting position for the fit), control flags coming from the extraction algorithm, and name of the radio map where the source has been detected. The name is specified for (1) pointlike sources that are detected in a multiple system (name = DSnnnn or TSnnnn) (2) sources initially classified as components of a double system, which has been considered spurious on the basis of the distance between components (name = Cnnnn or DCnnnn). File table2.dat contains the catalog of 2662 double radiosources. For each source the following parameters are given both for the barycentre and the two components: Right Ascension and Declination, source name, peak flux, flux rms from the fit, error on source position as estimated by the fitting algorithm, distance between the components of the double system, x and y pixel of the position where the peak has been detected on the map (starting position for the fit), control flags coming from the extraction algorithm, and name of the radio map where the source has been detected.
- ID:
- ivo://CDS.VizieR/J/A+A/379/35
- Title:
- Radio-optically selected galaxy clusters. II.
- Short Name:
- J/A+A/379/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1.dat contains data relative to spectroscopic and photometric observations of galaxies in 12 radio-optically selected candidate clusters. Observations have been acquired with the 3.6m ESO telescope, Chile. For each galaxy in the cluster, a sequential number, the magnitude in r-Gunn filter, the measured velocity, velocity rms, and notes to identify particular objects (emission galaxies, radiogalaxies and stars) are given.