- ID:
- ivo://CDS.VizieR/J/MNRAS/414/1397
- Title:
- Radio study of double-double radio galaxy 3C293
- Short Name:
- J/MNRAS/414/1397
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radio continuum observations at frequencies ranging from ~150 to 5000MHz of the misaligned double-double radio galaxy (DDRG) 3C 293 (J1352+3126) using the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA). The spectra of the outer lobes and the central source are consistent with being straight, indicating spectral ages of <~17-23Myr for the outer lobes and <~0.1Myr for the central source. The north-western lobe has a prominent hotspot suggesting that the interruption of jet activity is <~0.1Myr, consistent with the age of the inner double. The time-scale of interruption of jet activity appears significantly smaller than observed in most other DDRGs which are often associated with giant radio sources. These observations suggest that there is a wide range of time-scales of interruption of jet activity in active galaxies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/704/652
- Title:
- Radio transients in a 1.4GHz drift-scan survey
- Short Name:
- J/ApJ/704/652
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report two new radio transients at high Galactic latitude, WJN J0951+3300 (RA=09h51m22s+/-10s, DE=33{deg}00'+/-0.4{deg}, b=50{deg}54.2') and WJN J1039+3300 (RA=10h39m26s+/-10s, DE=33{deg}00'+/-0.4{deg}, b=60{deg}58.5'), which were detected by interferometric drift-scan observations at 1.4GHz at the Waseda Nasu Pulsar Observatory. WJN J0951+3300 was detected at 16:49:32UT on 2006 January 12 with the flux density of approximately 1760.5+/-265.9mJy, and WJN J1039+3300 was detected at 17:13:32UT on 2006 January 18 with the flux density of approximately 2242.5+/-228.7mJy. Both of them lasted for a short duration (<=2 days). The possibility that the distribution of the WJN radio transients is isotropic was suggested in a previous study. Having re-evaluated the log N-log S relation with the addition of the two new objects reported in this paper, we find that the slope is consistent with a slope of -1.5 and the previous result. Additionally, although there are several counterparts to WJN radio transients, we found that one of the quasar counterparts within the positional error of WJN J0951+3300 could be a radio-loud quasar. We have discussed whether or not WJN J0951+3300 could be of this quasar origin.
- ID:
- ivo://CDS.VizieR/J/MNRAS/450/2658
- Title:
- RATAN-600 flux densities of 123 blazars
- Short Name:
- J/MNRAS/450/2658
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the correlation between gamma-ray and radio band radiation for 123 blazars, using the Fermi-LAT first source catalog (1FGL) and the RATAN-600 data obtained at the same period of time (within a few months).
- ID:
- ivo://CDS.VizieR/J/other/AstBu/69.266
- Title:
- RATAN-600 flux densities of 37 blazars
- Short Name:
- J/other/AstBu/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the correlation between the emission from the broad-line region (BLR) and the emission in other wavelength ranges (from radio to x-ray) for the sample of 37 blazars (25 flat-spectrum radio quasars (FSRQs) and 10 BL Lac blazars). Studying the relation between luminosities in various wavebands and the BLR luminosity is an effective method to examine the connection between the accretion rate and the luminosity of the jet.We used simultaneous RATAN-600measurements of blazar flux densities at six frequencies: 1.1, 2.3, 4.8, 7.7, 11.2, and 21.7GHz. The observational data from other bands was taken from the literature. To determine the effect produced by the state of the object on the correlation, for the radio data we used the measurements obtained with the RATAN-600 in two states-namely, the maximum and minimum flux density values.We show that at some frequencies of the radio band, there exists a correlation of emission with the emission in the BLR for two types of blazars. In the FSRQ and BL Lac blazars, the correlation between the flux from the BLR and the flux in the radio band is indistinguishable in all cases, except for the case when a strong flux density variation was considered for the BL Lac-type of blazars (tens of percent). At the same time, the levels of significance for BL Lac (at certain frequencies p is worse than 0.05) in the active state indicate only the probable presence of connection. On the example of the sample, we show that the variability of emission significantly affects the level of correlation. Our results are consistent with the theoretical predictions about the close relationship of the accretion disk and the jet in blazars.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/65.42
- Title:
- RCR (RATAN COLD REFINED) catalogue
- Short Name:
- J/other/AstBu/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use two independent methods to reduce the data of the surveys made with RATAN-600 radio telescope at 7.6cm in 1988-1999 at the declination of the SS433 source. We also reprocess the data of the "Cold" survey (1980-1981). The resulting RCR (RATAN COLD REFINED) catalogue contains the right ascensions and fluxes of objects identified with those of the NVSS catalogue in the right-ascension interval 7h<=RA<=17h. We obtain the spectra of the radio sources and determine their spectral indices at 3.94 and 0.5GHz. The spectra are based on the data from all known catalogues available from the CATS, Vizier, and NED databases, and the flux estimates inferred from the maps of the VLSS and GB6 surveys. For 245 of the 550 objects of the RCR catalogue the fluxes are known are known only at two frequencies: 3.94GHz (RCR) and 1.4GHz (NVSS). These are mostly sources with fluxes smaller than 30mJy. About 65% of these sources have flat or inverse spectra (alpha>-0.5). We analyse the reliability of the results obtained for the entire list of objects and construct the histograms of the spectral indices and fluxes of the sources. Our main conclusion is that all 10-15mJy objects found in the considered right-ascension interval were already included in the decimetre-wave catalogues.
- ID:
- ivo://CDS.VizieR/J/ApJ/758/84
- Title:
- Relativistic jets in the RRFID database. II. 10yr
- Short Name:
- J/ApJ/758/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze blazar jet apparent speeds and accelerations from the RDV series of astrometric and geodetic very long baseline interferometry (VLBI) experiments. From these experiments, we have produced and analyzed 2753 global VLBI images of 68 sources at 8GHz with a median beam size of 0.9 milliarcseconds (mas) and a median of 43 epochs per source. From this sample, we analyze the motions of 225 jet components in 66 sources. The distribution of the fastest measured apparent speed in each source has a median of 8.3c and a maximum of 44c. Sources in the 2FGL Fermi LAT catalog display higher apparent speeds than those that have not been detected. On average, components farther from the core in a given source have significantly higher apparent speeds than components closer to the core; for example, for a typical source, components at ~3mas from the core (~15pc projected at z~0.5) have apparent speeds about 50% higher than those of components at ~1mas from the core (~5pc projected at z~0.5). We measure accelerations of components in orthogonal directions parallel and perpendicular to their average velocity vector. Parallel accelerations have significantly larger magnitudes than perpendicular accelerations, implying that observed accelerations are predominantly due to changes in the Lorentz factor (bulk or pattern) rather than projection effects from jet bending. Positive parallel accelerations are significantly more common than negative ones, so the Lorentz factor (bulk or pattern) tends to increase on the scales observed here. Observed parallel accelerations correspond to modest source frame increases in the bulk or pattern Lorentz factor.
- ID:
- ivo://CDS.VizieR/J/ApJ/878/92
- Title:
- Rotation measures in radio source pairs
- Short Name:
- J/ApJ/878/92
- Date:
- 03 Mar 2022 08:14:01
- Publisher:
- CDS
- Description:
- Faraday rotation measures (RMs) of extragalactic radio sources provide information on line-of-sight magnetic fields, including contributions from our Galaxy, source environments, and the intergalactic medium (IGM). Looking at differences in RMs, {Delta}RM, between adjacent sources on the sky can help isolate these different components. In this work, we classify adjacent polarized sources in the NRAO VLA Sky Survey (NVSS) as random or physical pairs. We recompute and correct the uncertainties in the NVSS RM catalog, since these were significantly overestimated. Our sample contains 317 physical and 5111 random pairs, all with Galactic latitudes |b|>=20{deg}, polarization fractions >=2%, and angular separations between 1.5' and 20'. We find an rms {Delta}RM of 14.9+/-0.4 and 4.6+/-1.1rad/m^2^ for the random and physical pairs, respectively. This means that polarized extragalactic sources that are close on the sky but at different redshifts have larger differences in RM than two components of one source. This difference of ~10rad/m^2^ is significant at 5{sigma} and persists in different data subsamples. While there have been other statistical studies of {Delta}RM between adjacent polarized sources, this is the first unambiguous demonstration that some of this RM difference must be extragalactic, thereby providing a firm upper limit on the RM contribution of the IGM. If the {Delta}RMs originate local to the sources, then the local magnetic field difference between random sources is a factor of 2 larger than that between components of one source. Alternatively, attributing the difference in {Delta}RMs to the intervening IGM yields an upper limit on the IGM magnetic field strength of 40nG.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A56
- Title:
- Rotation Measure synthesis of WSRT obs.
- Short Name:
- J/A+A/549/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation Measure synthesis (RM synthesis) of the Westerbork Synthesis Radio Telescope (WSRT) observations at 2m wavelength of the FAN region at l=137deg, b=+7deg shows the morphology of structures in the ionized interstellar medium.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/199
- Title:
- RRL and continuum data of 21 Galactic H II regions
- Short Name:
- J/ApJ/806/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Elemental abundance patterns in the Galactic disk constrain theories of the formation and evolution of the Milky Way. H II region abundances are the result of billions of years of chemical evolution. We made radio recombination line and continuum measurements of 21 H II regions located between Galactic azimuth Az=90{deg}-130{deg}, a previously unexplored region. We derive the plasma electron temperatures using the line-to-continuum ratios and use them as proxies for the nebular [O/H] abundances, because in thermal equilibrium the abundance of the coolants (O, N, and other heavy elements) in the ionized gas sets the electron temperature, with high abundances producing low temperatures. Combining these data with our previous work produces a sample of 90 H II regions with high-quality electron temperature determinations. We derive kinematic distances in a self-consistent way for the entire sample. The radial gradient in [O/H] is -0.082+/-0.014 dex/kpc for Az=90{deg}-130{deg}, about a factor of 2 higher than the average value between Az=0{deg}-60{deg}. Monte Carlo simulations show that the azimuthal structure we reported for Az=0{deg}-60{deg} is not significant because kinematic distance uncertainties can be as high as 50% in this region. Nonetheless, the flatter radial gradients between Az=0{deg}-60{deg} compared with Az=90{deg}-130{deg} are significant within the uncertainty. We suggest that this may be due to radial mixing from the Galactic Bar whose major axis is aligned toward Az~30{deg}.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A153
- Title:
- SAGAN. I. New sample & multi-wavelength studies
- Short Name:
- J/A+A/642/A153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a project called SAGAN, which is dedicated solely to the studies of relatively rare megaparsec-scale radio galaxies in the Universe, called giant radio galaxies (GRGs). We have identified 162 new GRGs primarily from the NVSS with sizes ranging from ~0.71Mpc to 2.82Mpc in the redshift range of ~0.03-0.95, of which 23 are hosted by quasars (giant radio quasars, GRQs). As part of the project SAGAN, we have created a database of all known GRGs, the GRG catalogue, from the literature (including our new sample); it includes 820 sources. For the first time, we present the multi-wavelength properties of the largest sample of GRGs. Our results establish that the distributions of the radio spectral index and the black hole mass of GRGs do not differ from the corresponding distributions of normal-sized radio galaxies (RGs). However, GRGs have a lower Eddington ratio (ER) than RGs. Using the mid-infrared data, we classified GRGs in terms of their accretion mode: either a high-power radiatively efficient high-excitation state, or a radiatively inefficient low-excitation state. We find that GRGs in high-excitation state statistically have larger sizes, stronger radio power, jet kinetic power, and higher ER than those in low-excitation state. Our analysis reveals a strong correlation between the ER and the scaled jet kinetic power, which suggests a disc-jet coupling. Our environmental study reveals that ~10% of all GRGs may reside at the centres of galaxy clusters, in a denser galactic environment, while the majority appears to reside in a sparse environment. We find that the probability of BCG as a GRG is quite low. We present new results for GRGs that range from black hole mass to large-scale environment properties. We discuss their formation and growth scenarios, highlighting the key physical factors that cause them to reach their gigantic size.
