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1351. Radio jet emission from GeV-emitting NLSy1
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.
1352. Radio-loud and radio-quiet quasars sample
ID:
ivo://CDS.VizieR/J/MNRAS/461/2346
Title:
Radio-loud and radio-quiet quasars sample
Short Name:
J/MNRAS/461/2346
Date:
21 Oct 2021
Publisher:
CDS
Description:
We compare covering factors of circumnuclear dusty obscurers in radio-loud and radio-quiet quasars. The radio-loud quasars are represented by a sample of FR II quasars obtained by cross-matching a catalog of the FR II radio sources selected by van Velzen et al. with the SDSS DR7 catalog of quasars. Covering factors of FR II quasars are compared with covering factors of the radio-quiet quasars matched with them in redshift, black hole mass, and Eddington-ratio. We found that covering factors, proxied by the infrared-to-bolometric luminosity ratio, are on average slightly smaller in FR II quasars than in radio-quiet quasars, however, this difference is statistically significant only for the highest Eddington ratios. For both samples, no statistically significant dependence of a median covering factor on Eddington ratio, black hole mass, nor redshift can be claimed.
1353. Radio loudness of active galactic nuclei
ID:
ivo://CDS.VizieR/J/ApJ/658/815
Title:
Radio loudness of active galactic nuclei
Short Name:
J/ApJ/658/815
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate how the total radio luminosity of AGN-powered radio sources depends on their accretion luminosity and the central black hole mass. Our studies cover about 7 orders of magnitude in accretion luminosity (expressed in Eddington units, i.e., as Eddington ratios) and the full range of AGN black hole masses.
1354. Radio-loud QSOs at z~4
ID:
ivo://CDS.VizieR/J/MNRAS/348/857
Title:
Radio-loud QSOs at z~4
Short Name:
J/MNRAS/348/857
Date:
21 Oct 2021
Publisher:
CDS
Description:
We obtained spectra of 60 red, star-like objects (m_E_<18.8) identified with FIRST radio sources, S_1.4GHz_>1mJy. Eight are quasi-stellar objects (QSOs) with redshift z>3.6. Combined with our earlier pilot search, our sample of 121 candidates yields a total of 18 z>3.6 QSOs (10 of these with z>4.0). 8 per cent of candidates with S_1.4GHz_<10mJy and 37 per cent of candidates with S_1.4GHz_>10mJy are QSOs with z>3.6. The surface density of m_E_<18.8, S_1.4GHz_>1mJy, z>4 QSOs is 0.003deg^-2^. This is currently the only well-defined sample of radio-loud QSOs at z~4 selected independently of radio spectral index. The QSOs are highly luminous in the optical (eight have M_B_<28, q_0_=0.5, H_0_=50km/s/Mpc). The SEDs are as varied as those seen in optical searches for high-redshift QSOs, but the fraction of objects with weak (strongly self-absorbed) Ly emission is marginally higher (3 out of 18) than for high-redshift QSOs from SDSS (5 out of 96).
1355. 87 radio loud quasars (RLS) with 3.6<=z<=4.4
ID:
ivo://CDS.VizieR/J/MNRAS/449/2818
Title:
87 radio loud quasars (RLS) with 3.6<=z<=4.4
Short Name:
J/MNRAS/449/2818
Date:
21 Oct 2021
Publisher:
CDS
Description:
We obtain a sample of 87 radio-loud quasi-stellar objects (QSOs) in the redshift range 3.6<=z<=4.4 by cross-correlating sources in the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio survey (S_1.4GHz_>1mJy) with star-like objects having r<20.2 in Sloan Digital Sky Survey (SDSS) Data Release 7. Of these 87 QSOs, 80 are spectroscopically classified in previous work (mainly SDSS), and form the training set for a search for additional such sources. We apply our selection to 2916 FIRST-DR7 pairs and find 15 likely candidates. Seven of these are confirmed as high-redshift quasars, bringing the total to 87. The candidates were selected using a neural-network, which yields 97 percent completeness (fraction of actual high-z QSOs selected as such) and an efficiency (fraction of candidates which are high-z QSOs) in the range of 47-60 percent. We use this sample to estimate the binned optical luminosity function (LF) of radio-loud QSOs at z~4, and also the LF of the total QSO population and its comoving density. Our results suggest that the radio-loud fraction at high z is similar to that at low z and that other authors may be underestimating the fraction at high z. Finally, we determine the slope of the optical LF and obtain results consistent with previous studies of radio-loud QSOs and of the whole population of QSOs. The evolution of the LF with redshift was for many years interpreted as a flattening of the bright-end slope, but has recently been re-interpreted as strong evolution of the break luminosity for high-z QSOs, and our results, for the radio-loud population, are consistent with this.
1356. Radio-loud ROSAT sources near NEP
ID:
ivo://CDS.VizieR/J/A+AS/134/221
Title:
Radio-loud ROSAT sources near NEP
Short Name:
J/A+AS/134/221
Date:
21 Oct 2021
Publisher:
CDS
Description:
A deep and large-area survey of the North Ecliptic Pole region was made with the ROSAT All-Sky Survey and the VLA to elucidate the population of radio-loud extragalactic objects. A region of 29.3 square degrees was surveyed with sensitivities around 5x10^-14^erg/s/cm^2^ in the soft X-ray band and 1mJy at 1.5GHz. Optical counterparts were sought on digitized Schmidt plates from POSS-I and II. Seventy-four reliable RASS-VLA sources were found. The sample is a heterogeneous mixture of Seyfert galaxies, quasars, BL Lac objects, galaxy clusters and groups containing a radio galaxy. Optical magnitudes range from B=~14 to B>22. Three results are noteworthy: (1) the bimodality in the ratio of radio to optical emission seen in optically- and X-ray-selected AGN samples is also evident in the ROSAT-VLA objects; (2) X-ray and radio selection is an effective method for locating poor galaxy clusters and groups; and (3) a considerable population of optically faint but X-ray/radio-bright objects is present. This last group may be either distant clusters with radio galaxies or "red quasars".
1357. Radio luminosities of normal & millisecond pulsars
ID:
ivo://CDS.VizieR/J/AZh/79/501
Title:
Radio luminosities of normal & millisecond pulsars
Short Name:
J/AZh/79/501
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of comparative statistical analysis of the integrated radio luminosities of normal and millisecond pulsars are presented. The analysis is based on our own measurements of the flux densities, spectra and integrated radio luminosities of the millisecond pulsars., as well as data from the literature used to determine the integrated radio luminosities for 545 pulsars.
1358. Radio luminosities of 232 pulsars
ID:
ivo://CDS.VizieR/J/AZh/71/762
Title:
Radio luminosities of 232 pulsars
Short Name:
J/AZh/71/762
Date:
21 Oct 2021
Publisher:
CDS
Description:
Total radio luminosities of 232 pulsars are calculated using new data on mean spectra. For 88% of these pulsars, luminosities lie in the range 10^27^-10^30^erg/s. It is shown that pulsar luminosity remains constant over a period of a few million years. Mean radiation power increases with period P as P^0.5^. An increase in luminosity with the rotational energy loss rate is found.
1359. Radio luminosity function of FSRQs
ID:
ivo://CDS.VizieR/J/ApJ/842/87
Title:
Radio luminosity function of FSRQs
Short Name:
J/ApJ/842/87
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the radio luminosity function (LF) of flat-spectrum radio quasars (FSRQ), using the largest and most complete sample to date. Cross-matching between the FIRST 20cm and GB6 6cm radio surveys, we find 638 flat-spectrum radio sources above 220mJy at 1.4GHz; of these, 327 are classified and verified using optical spectroscopy data, mainly from Sloan Digital Sky Survey Data Release 12. We also considered flat-spectrum radio sources that lack both literature references and optical spectroscopy, and we identified 12 out of the 43 such sources to potentially be FSRQs, using their WISE colors. From the fully identified sample of 242 FSRQs, we derived the radio LF and cosmic evolution of blazars at 1.4GHz, finding good agreement with previous work at 5GHz. The number density of FSRQs increases dramatically to a redshift of z~2 and then declines for higher redshifts. Furthermore, the redshift at which the quasar density peaks is clearly dependent on luminosity, with more luminous sources peaking at higher redshifts. The approximate best-fit LF for a luminosity-dependent evolutionary model is a broken power-law with slopes ~0.7 and ~1.7 below and above the break luminosity, logL_1.4_~43.8erg/s, respectively.
1360. Radio maps of Infrared Dark Cloud 18223-3
ID:
ivo://CDS.VizieR/J/A+A/504/127
Title:
Radio maps of Infrared Dark Cloud 18223-3
Short Name:
J/A+A/504/127
Date:
21 Oct 2021
Publisher:
CDS
Description:
We examine an Infrared Dark Cloud (IRDC) at high spatial resolution as a means to study rotation, outflow, and infall at the onset of massive star formation. The IRDC 18223-3 was observed at 1.1mm and 1.3mm with the Submillimeter Array (SMA) and follow-up short spacing information was obtained with the IRAM 30m telescope. Additional data were taken at 3mm with the IRAM Plateau de Bure interferometer (PdBI).