- 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.
Number of results to display per page
Search Results
- 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.
- 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/AJ/135/2470
- Title:
- Radio observations of the HDFS region. IV.
- Short Name:
- J/AJ/135/2470
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Australia Telescope Hubble Deep Field-South (ATHDF-S) survey of the Hubble Deep Field-South (HDF-S) reaches sensitivities of ~10uJy at 1.4, 2.5, 5.2, and 8.7GHz, making the ATHDF-S one of the deepest surveys ever performed with the Australia Telescope Compact Array (ATCA). Here, we present the optical identifications of the ATHDF-S radio sources using data from the literature. We find that ~66% of the radio sources have optical counterparts to I=23.5mag. Deep Hubble Space Telescope (HST) imaging of the area identifies a further 12% of radio sources. We present new spectroscopic observations for 98 of the radio sources and supplement these spectroscopic redshifts with photometric ones calculated from five-band optical imaging.
- 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/ApJ/903/132
- Title:
- Radio & optical observations of supernova SN2020oi
- Short Name:
- J/ApJ/903/132
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- We report the discovery and panchromatic follow-up observations of the young Type Ic supernova (SNIc) SN2020oi in M100, a grand-design spiral galaxy at a mere distance of 14Mpc. We followed up with observations at radio, X-ray, and optical wavelengths from only a few days to several months after explosion. The optical behavior of the supernova is similar to those of other normal SNeIc. The event was not detected in the X-ray band but our radio observations revealed a bright mJy source (L_{nu}_~1.2x10^27^erg/s/Hz). Given the relatively small number of stripped envelope SNe for which radio emission is detectable, we used this opportunity to perform a detailed analysis of the comprehensive radio data set we obtained. The radio-emitting electrons initially experience a phase of inverse Compton cooling, which leads to steepening of the spectral index of the radio emission. Our analysis of the cooling frequency points to a large deviation from equipartition at the level of {epsilon}_e_/{epsilon}_B_>~200, similar to a few other cases of stripped envelope SNe. Our modeling of the radio data suggests that the shock wave driven by the SN ejecta into the circumstellar matter (CSM) is moving at ~3x10^4^km/s. Assuming a constant mass loss from the stellar progenitor, we find that the mass-loss rate is M~1.4x10^-4^M{sun}/yr for an assumed wind velocity of 1000km/s. The temporal evolution of the radio emission suggests a radial CSM density structure steeper than the standard r-2.
- ID:
- ivo://CDS.VizieR/J/A+A/520/A62
- Title:
- Radio-optical scrutiny of compact AGN
- Short Name:
- J/A+A/520/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the correlations between the VLBA (Very Long Baseline Array) radio emission at 15GHz, extended emission at 151MHz, and optical nuclear emission at 5100{AA} for a complete sample of 135 compact jets. We use the partial Kendall's tau correlation analysis to check the link between radio properties of parsec-scale jets and optical nuclear luminosities of host active galactic nuclei (AGN).
- ID:
- ivo://CDS.VizieR/J/ApJS/185/124
- Title:
- 58 radio sources near BNGSs
- Short Name:
- J/ApJS/185/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a preliminary survey of 58 radio sources within the isoplanatic patches (r<25") of bright (11<R<12) stars suitable for use as natural guide stars with high-order adaptive optics (AO). An optical and near-infrared imaging survey was conducted utilizing tip-tilt corrections in the optical and AO in the near-infrared. Spectral energy distributions were fit to the multi-band data for the purpose of obtaining photometric redshifts using the Hyperz code. Several of these photometric redshifts were confirmed with spectroscopy, a result that gives more confidence to the redshift distribution for the whole sample. Additional long-wavelength data from Spitzer, SCUBA, SHARC2, and VLA supplement the optical and near-infrared data. We find the sample generally follows and extends the magnitude-redshift relation found for more powerful local radio galaxies. The survey has identified several reasonably bright (H=19-20) objects at significant redshifts (z>1) that are now within the capabilities of the current generation of AO-fed integral-field spectrographs. These objects constitute a unique sample that can be used for detailed ground-based AO studies of galactic structure, evolution, and active galactic nucleus formation at high redshift.
- ID:
- ivo://CDS.VizieR/J/MNRAS/391/297
- Title:
- Radio Survey of 7 X-ray Clusters of Galaxies
- Short Name:
- J/MNRAS/391/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Australia Telescope Compact Array (ATCA) has been used at 1.38 and 2.38GHz to survey seven southern Abell clusters of galaxies with high X-ray luminosities: A2746, A2837, A3126, A3216, A3230, A3827 and A3836. The clusters have also been surveyed at 0.843GHz with the Molonglo Observatory Synthesis Telescope (MOST). We have listed a complete 1.38-GHz sample of 149 radio sources within the Abell circles centred on their X-ray centroids. We compare their identification fractions, emitted 1.38-GHz and optical powers, radio spectral indices and radial variation in projected source density with those of the radio-selected samples of Slee et al. (1998AuJPh..51..971S). We compare our fractional radio luminosity function with that of the radio-selected samples of Ledlow and Owen (1996AJ....112....9L) and Slee et al. (1998AuJPh..51..971S). Three significant differences are noted between X-ray and radio-selected samples of clusters; (1) the X-ray sample has an excess of flat-spectrum radio sources; (2) the fractional radio luminosity function for the FR I sources in the X-ray selected sample is much steeper, implying that fewer of their cluster galaxies become hosts for the stronger FR I radio galaxies; (3) a complete absence of FR II radio galaxies in the X-ray selected sample. The average excess projected density of radio sources near our cluster centres is approx. 5 times the background source density.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/121
- Title:
- Radio to UV observations of GRB 181201A
- Short Name:
- J/ApJ/884/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present comprehensive multiwavelength radio to X-ray observations of GRB 181201A spanning from ~150s to ~163days after the burst, comprising the first joint ALMA-VLA-GMRT observations of a gamma-ray burst (GRB) afterglow. The radio and millimeter-band data reveal a distinct signature at ~3.9days, which we interpret as reverse-shock (RS) emission. Our observations present the first time that a single radio- frequency spectral energy distribution can be decomposed directly into RS and forward shock (FS) components. We perform detailed modeling of the full multiwavelength data set, using Markov Chain Monte Carlo sampling to construct the joint posterior density function of the underlying physical parameters describing the RS and FS synchrotron emission. We uncover and account for all discovered degeneracies in the model parameters. The joint RS-FS modeling reveals a weakly magnetized ({sigma}~3x10^-3^), mildly relativistic RS, from which we derive an initial bulk Lorentz factor of {Gamma}_0_~103 for the GRB jet. Our results support the hypothesis that low-density environments are conducive to the observability of RS emission. We compare our observations to other events with strong RS detections and find a likely observational bias selecting for longer lasting, nonrelativistic RSs. We present and begin to address new challenges in modeling posed by the present generation of comprehensive, multifrequency data sets.
