- ID:
- ivo://CDS.VizieR/J/AJ/102/1663
- Title:
- Radio properties of extragal. IRAS sources
- Short Name:
- J/AJ/102/1663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog presents radio and optical identifications of extragalactic IRAS sources from the IRAS Faint Source Catalog |b| > 50{deg} (Moshir et al., 1989 Cat. <II/156>). Sources with flux density > 0.2 at 60 microns and with S_60_ > S_12_ were identified by position coincidence with radio sources stronger than 25 mJy and lying north of declination = 5{deg} on the Green Bank 4.85 GHz sky map. Published VLA maps, new 4.86 GHz VLA maps made with 15 arcsec resolution, and accurate optical positions were used to confirm 122 candidate identifications. This catalog contains a merged version of tables 1 and 2 from the paper.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/560/A23
- Title:
- Radio properties of faint BL Lacs
- Short Name:
- J/A+A/560/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The advent of Fermi is changing our understanding on the radio and gamma-ray emission in Active Galactic Nuclei. Contrary to pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the gamma-ray band. However, since they are relatively weak radio sources, most of their parsec-scale structure and their multi-frequency properties are poorly understood and/or have not been investigated in a systematically fashion. Our main goal is to analyze the radio and gamma-ray emission properties of a sample of 42 BL Lacs selected, for the first time in the literature, with no constraint on their radio and gamma-ray flux densities/emission. Thanks to new Very Long Baseline Array observations at 8 and 15GHz for the whole sample, we present here fundamental parameters such as radio flux densities, spectral index information, and parsec-scale structure. Moreover, we search for gamma-ray counterparts using data reported in the Second Catalog of Fermi Gamma-ray sources. Parsec-scale radio emission is observed in the majority of the sources at both frequencies. Gamma-ray counterparts are found for 14/42 sources. The comparison between our results in radio and gamma-ray bands points out the presence of a large number of faint BL Lacs showing "non classical" properties such as low source compactness, core dominance, no gamma-ray emission and steep radio spectral indexes. A deeper multiwavelength analysis will be needed.
- ID:
- ivo://CDS.VizieR/J/ApJ/445/62
- Title:
- Radio properties of optically selected quasars
- Short Name:
- J/ApJ/445/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Approximately one-quarter (256 objects) of the Large Bright Quasar Survey (LBQS, Hewett et al., 1995, Cat. <J/AJ/109/1498>) has been observed with the VLA at 8.4GHz, resulting in 44 detections (17%) with a median 3{sigma} noise limit of 0.29mJy. Quasars with radio luminosity detectable at this limit are under-represented at faint absolute blue magnitudes (M_B_>=-24), an effect which cannot be explained by a potential LBQS selection bias against quasars which have large radio luminosities and small optical luminosities. The radio-loud (8GHz luminosity >10^25^W/Hz) fraction is observed to change as a function of redshift and MB, for M_B_<-24, although the causal variable is ambiguous. The description most consistent with the available data is that radio-loud fraction is approximately constant over the range -27.5<M_B_<-24 and increases at brighter absolute magnitudes. The radio-loud fraction as a function of redshift reaches a local maximum at z~1, and, aside from the effects of increased radio-loud fraction at bright M_B_, remains roughly constant to redshifts approaching 5. The log R_8.4_ distribution (radio-to-optical luminosity ratio) of the current LBQS sample may be bimodal, but the results of statistical tests are ambiguous, requiring a larger sample size to become definite.
- ID:
- ivo://CDS.VizieR/J/other/PPMtO/17B.1
- Title:
- Radio properties of ROSAT sources
- Short Name:
- J/other/PPMtO/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A cross-identification of the southern-sky objects with the ROSAT All-Sky Survey (Cat. <IX/10>) and Parkes-MIT-NRAO (PMN) Radio (5GHz) Survey (Cat. <VIII/38>) yields a list of 642 sources. Subsequential optical identification for all these coincidences has been taken to form a large sample of galaxies and Active Galactic Nuclei (AGNs). As a result, 311 (52%) were previously optically identified as extragalactic objects. The fluxes detected from X-ray, optical, and radio bands for them are compiled. This database allows an investigation on broad band energy distribution and other possible correlations among spectral indices and luminosities for various types of extragalactic objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/125
- Title:
- Radio properties of Swift/BAT AGNs
- Short Name:
- J/ApJ/900/125
- Date:
- 02 Feb 2022 09:04:43
- Publisher:
- CDS
- Description:
- We address the very large diversity of jet production efficiency in active galactic nuclei (AGNs) by using data on low-redshift AGNs selected from the Swift/BAT catalog and having black hole (BH) masses larger than 10^8.5^M_{sun}_. Most of these AGNs accrete at intermediate rates and have bolometric luminosities dominated by mid-IR radiation. Our sample contains 14% radio-loud (RL), 6% radio-intermediate, and 80% radio-quiet (RQ) AGNs. All RL objects are found to have extended radio structures, and most of them have classical FR II morphology. Converting their radio loudness to jet production efficiency, we find that the median of this efficiency is on the order of ({epsilon}_d_/0.1)%, where {epsilon}_d_=L_bol_/(dM/dt)c^2^ is the radiation efficiency of the accretion disk. Without knowing the contribution of jets to the radio emission in RQ AGNs, we are only able to estimate their efficiencies using upper limits. Their median is found to be 0.002({epsilon}_d_/0.1)%. Our results suggest that some threshold conditions must be satisfied to allow the production of strong, relativistic jets in RL AGNs. We discuss several possible scenarios and argue that the production of collimated, relativistic jets must involve the Blandford-Znajek mechanism and can be activated only in those AGNs whose lifetime is longer than the time required to enter the magnetically arrested disk (MAD). Presuming that MAD is required to collimate relativistic jets, we expect that the weak nonrelativistic jets observed in some RQ AGNs are produced by accretion disks rather than by rotating BHs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/921
- Title:
- Radio properties of z < 0.3 quasars
- Short Name:
- J/MNRAS/466/921
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To better constrain the hypotheses proposed to explain why only a few quasars are radio loud (R_L_), we compare the characteristics of 1958 nearby (z<=0.3) SDSS (Sloan Digital Sky Survey) quasars, covered by the FIRST (Faint Images of the Radio Sky at Twenty Centimeters) and NVSS (NRAO VLA Sky Survey) radio surveys. Only 22 per cent are R_L_ with log(L_1.4GHz_)>=22.5W/Hz, the majority being compact (C), weak radio sources (WRS), with log(L_1.4GHz_)<24.5W/Hz. 15 per cent of the RL quasars have extended radio morphologies: 3 per cent have a core and a jet (J), 2 per cent have a core with one lobe (L), and 10 per cent have a core with two lobes (T), the majority being powerful radio sources (PRS), with log(L_1.4GHz_)>=24.5W/Hz. In general, RL quasars have higher bolometric luminosities and ionization powers than radio-quiet (RQ) quasars. The WRS have comparable black hole (BH) masses as the RQ quasars, but higher accretion rates or radiative efficiencies. The PRS have higher BH masses than the WRS, but comparable accretion rates or radiative efficiencies. The WRS also have higher FWHM_{[OIII]} than the PRS, consistent with a coupling of the spectral characteristics of the quasars with their radio morphologies. Inspecting the SDSS images and applying a neighbour search algorithm reveal no difference between the RQ and RL quasars of their host galaxies, environments, and interaction. Our results prompt the conjecture that the phenomenon that sparks the RL phase in quasars is transient, intrinsic to the active galactic nuclei, and stochastic, due to the chaotic nature of the accretion process of matter on to the BHs.
- ID:
- ivo://CDS.VizieR/J/ApJS/165/338
- Title:
- Radio recombination lines in HII regions
- Short Name:
- J/ApJS/165/338
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report radio recombination line (RRL) and continuum observations of a sample of 106 Galactic HII regions made with the NRAO 140 Foot (43m) radio telescope in Green Bank, West Virginia. We believe this to be the most sensitive RRL survey ever made for a sample this large. Most of our source integration times range between 6 and 90 hr, yielding typical rms noise levels of ~1.0-3.5mK. Our data result from two different experiments performed, calibrated, and analyzed in similar ways. A CII survey was made at the 3.5cm wavelength to obtain accurate measurements of carbon radio recombination lines. When combined with atomic (CI) and molecular (CO) data, these measurements will constrain the composition, structure, kinematics, and physical properties of the photodissociation regions that lie on the edges of HII regions. A second survey was made at the 3.5cm wavelength to determine the abundance of ^3^He in the interstellar medium of the Milky Way. Together with measurements of the ^3^He^+^ hyperfine line, we get high-precision RRL parameters for H, ^4^He, and C. Here we discuss significant improvements in these data with both longer integrations and newly observed sources.
- ID:
- ivo://CDS.VizieR/J/A+A/171/261
- Title:
- Radio Recombination Lines of Southern HII Regions
- Short Name:
- J/A+A/171/261
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We tabulate velocities and other parameters of hydrogen recombination lines near 5GHz (H109{alpha} and H110{alpha}) for 316 HII regions observed with the Parkes 64-m radio telescope. Results of a new search for formaldehyde absorption are also listed. Source selection was based on the 5GHz continuum southern galactic plane survey of Haynes et al. (1978, 1979). Data is given for most H II regions in the galactic longitude range 210 to 360 degrees that show 5GHz continuum brightness temperature exceeding 1K (as observed with the 4 arcminute beam of the Parkes 64-m telescope), together with a selection of sources that are weaker or outside of this longitude range. Tabulated data include source coordinates, peak brightness, flux density, and angular size from the 5GHz continuum survey; radial velocities of detected formaldehyde absorption lines; recombination line peak brightness, radial velocity, and line width; derived electron temperature assuming LTE; derived kinematic distance from the Sun and galactocentric radius; and presence or absence of a visible optical counterpart. In cases where kinematic distance is ambiguous, both near and far distances are tabulated; a flag is given if there is a strong preference for near or far distance based on information such as H I or H2CO absorption measurements or visibility of an optical counterpart. Many of these radio HII regions lie beyond the range of optical detection, at distances exceeding several kpc; they thus provide a comprehensive coverage of the southern HII regions in the Galaxy over the longitude range 210 to 360 degrees and constitute a vital data base for the study of galactic structure.
1389. Radio reference frame
- ID:
- ivo://CDS.VizieR/J/AJ/110/880
- Title:
- Radio reference frame
- Short Name:
- J/AJ/110/880
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue is presented based on the radio positions of 436 extragalactic sources distributed over the entire sky. The positional accuracy of the sources is better than 3 milliarcsec (mas) in both coordinates, with the majority of the sources having errors better than 1mas. This catalogue is based upon a general solution of all applicable dual frequency 2.3 and 8.4GHz Mark-III VLBI data available through the end of 1993 consisting of 1,015,292 pairs of group delay and phase delay rate observations. Details and positions are also given for an additional 124 objects that either need further observation or are currently unsuitable for the definition of a reference frame. The final orientation of the catalogue has been obtained by a rotation of the positions into the system of the International Earth Rotation Service and is consistent with the FK5 J2000.0 optical system, within the limits of the link accuracy.
- ID:
- ivo://CDS.VizieR/J/ApJ/882/69
- Title:
- Radio relic merging galaxy cluster substructures
- Short Name:
- J/ApJ/882/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Golovich et al. (2019, J/ApJS/240/39) present an optical imaging and spectroscopic survey of 29 radio relic merging galaxy clusters. In this paper, we study this survey to identify substructure and quantify the dynamics of the mergers. Using a combined photometric and spectroscopic approach, we identify the minimum number of substructures in each system to describe the galaxy populations and estimate the line-of-sight velocity difference between likely merging subclusters. We find that the line-of-sight velocity components of the mergers are typically small compared with the maximum 3D relative velocity (usually <1000km/s and often consistent with zero). We also compare our systems to n-body simulation analogs and estimate the viewing angle of the clean mergers in our ensemble. We find that the median system's separation vector lies within 40{deg} (17{deg}) at a 90% (50%) confidence level. This suggests that the merger axes of these systems are generally in or near the plane of the sky, matching findings in magnetohydrodynamical simulations. In 28 of the 29 systems we identify substructures in the galaxy population aligned with the radio relic(s) and presumed associated merger-induced shock. From this ensemble, we identify eight systems to include in a "gold" sample that is prime for further observation, modeling, and simulation study. Additional papers will present weak-lensing mass maps and dynamical modeling for each merging system, ultimately leading to new insight into a wide range of astrophysical phenomena at some of the largest scales in the universe.
