- ID:
- ivo://CDS.VizieR/J/A+A/658/A135
- Title:
- RS Cnc IRAM NOEMA interferometric data
- Short Name:
- J/A+A/658/A135
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The latest evolutionary phases of low- and intermediate mass stars are characterized by complex physical processes like turbulence, convection, stellar pulsations, magnetic fields, condensation of solid particles, and the formation of massive outflows that inject freshly produced heavy elements and dust particles into the interstellar medium. By investigating individual objects in detail we wish to analyze and disentangle the effects of the interrelated physical processes on the structure of the wind forming region around these objects. We use the Northern Extended Millimeter Array (NOEMA) to obtain spatially and spectrally resolved observations of the semi-regular Asymptotic Giant Branch star RS Cancri to shed light on the morpho-kinematic structure of its inner, wind forming environment by applying detailed 3-D reconstruction modeling and LTE radiative transfer calculations. We detect 32 lines of 13 molecules and isotopologs (CO, SiO, SO, SO_2_, H_2_O, HCN, PN), including several transitions from vibrationally excited states. HCN, H^13^CN, millimeter vibrationally excited H_2_O, SO, ^34^SO, SO_2_, and PN are detected for the first time in RS Cnc. Evidence for rotation is seen in HCN, SO, SO_2_, and SiO(v=1). From CO and SiO channel maps, we find an inner, equatorial density enhancement, and a bipolar outflow structure with a mass loss rate of 1x10^-7^M_{sun}_/yr for the equatorial region and of 2x10^-7^M_{sun}_/yr for the polar outflows. The ^12^CO/^13^CO ratio is measured to be ~20 on average, 24+/-2 in the polar outflows and 19+/-3 in the equatorial region. We do not find direct evidence of a companion that might explain this kind of kinematic structure, and explore the possibility that a magnetic field might be the cause of it. The innermost molecular gas is influenced by stellar pulsation and possibly by convective cells that leave their imprint on broad wings of certain molecular lines, such as SiO and SO. RS Cnc is one of the few nearby, low mass-loss-rate, oxygen-rich AGB stars with a wind displaying both an equatorial disk and bipolar outflows. Its orientation with respect to the line of sight is particularly favorable for a reliable study of its morpho-kinematics. The mechanism causing early spherical symmetry breaking remains however uncertain, calling for additional high spatial and spectral resolution observations of the emission of different molecules in different transitions, along with a deeper investigation of the coupling among the different physical processes at play.
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- ID:
- ivo://CDS.VizieR/J/A+A/642/A85
- Title:
- RX J0603.3+4214 LOFAR 58GHz images
- Short Name:
- J/A+A/642/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ultra-low frequency observations (<100MHz) are particularly challenging because they are usually performed in a low signal-to-noise ratio regime due to the high sky temperature and because of ionospheric disturbances whose effects are inversely proportional to the observing frequency. Nonetheless, these observations are crucial for studying the emission from low-energy populations of cosmic rays. We aim to obtain the first thermal-noise limited (~1.5mJy/beam) deep continuum radio map using the Low Frequency Array's Low Band Antenna (LOFAR LBA) system. Our demonstration observation targeted the galaxy cluster RX J0603.3+4214 (known as the Toothbrush cluster). We used the resulting ultra-low frequency (39-78MHz) image to study cosmic-ray acceleration and evolution in the post shock region considering the presence of a radio halo. We describe the data reduction we used to calibrate LOFAR LBA observations. The resulting image was combined with observations at higher frequencies (LOFAR 150MHz and VLA 1500MHz) to extract spectral information.Results.We obtained the first thermal-noise limited image from an observation carried out with the LOFAR LBA system using allDutch stations at a central frequency of 58MHz. With eight hours of data, we reached an rms noise of 1.3mJy/beam at a resolution of 18"x11". The procedure we developed is an important step towards routine high-fidelity imaging with the LOFAR LBA. Theanalysis of the radio spectra shows that the radio relic extends to distances of 800kpc downstream from the shock front, larger than what is allowed by electron cooling time. Furthermore, the shock wave started accelerating electrons already at a projected distance of <300kpc from the crossing point of the two clusters. These results may be explained by electrons being re-accelerated down stream by background turbulence, possibly combined with projection effects with respect to the radio halo.
- 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.
1494. Sample of 966 AGNs
- ID:
- ivo://CDS.VizieR/J/other/RAA/20.25
- Title:
- Sample of 966 AGNs
- Short Name:
- J/other/RAA/20.2
- Date:
- 03 Dec 2021 00:39:07
- Publisher:
- CDS
- Description:
- Active galactic nuclei (AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type I and type II (FRI&II) radio galaxies. Following our previous work, we present a latest sample of 966 sources with measured radio flux densities of the core and extended components. The sample includes 83 BL Lacs, 473 flat spectrum radio quasars, 101 Seyferts, 245 galaxies, 52 FRIs&IIs and 12 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and radio spectral index extends over all the sources in a large sample presented.
1495. Sample of 2400 AGNs
- ID:
- ivo://CDS.VizieR/J/other/RAA/19.70
- Title:
- Sample of 2400 AGNs
- Short Name:
- J/other/RAA/19.7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Active galactic nuclei (AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type I/II (FRI/II) radio galaxies. Following our previous work (Fan et al., 2011RAA....11.1413F), we present a sample of 2400 sources with measured radio flux densities of the core and extended components. The sample contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRII galaxies and 104 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices, and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and spectral index exists for a large sample presented in this work.
1496. Sample of 877 blazars
- ID:
- ivo://CDS.VizieR/J/other/AstBu/70.264
- Title:
- Sample of 877 blazars
- Short Name:
- J/other/AstBu/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the synchrotron component of the spectral energy distribution on the sample of 877 blazars using ASDC SED Builder Tool with available broadband data from the literature. Our sample includes 423 flat-spectrum radio sources (FSRQs), 361 BL Lac objects and candidates, and 93 blazars of uncertain type. We have made an estimation of the synchrotron peak frequency for the 875 objects and further classified them as high, intermediate and low synchrotron peaked sources (HSPs/ISPs/LSPs). For each source NVSS name (RA (HHMMSS) and DEC (DDMMSS) for the J2000.0 epoch), alias, redshift, R band magnitude, synchrotron peak frequency, correlation coefficient, flux density at 4.8GHz, SED class, blazar type and selection method are presented.
- ID:
- ivo://CDS.VizieR/J/AJ/135/2453
- Title:
- Sample of BL Lac objects from SDSS and FIRST
- Short Name:
- J/AJ/135/2453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a large sample of 501 radio-selected BL Lac candidates from a combination of Sloan Digital Sky Survey (SDSS) Data Release 5 optical spectroscopy and the Faint Images of the Radio Sky at 20cm (FIRST) radio survey; this is one of the largest BL Lac samples yet assembled, and each object emerges with homogeneous data coverage. Each candidate is detected in the radio from FIRST and confirmed in SDSS optical spectroscopy to have (1) no emission feature with measured rest-equivalent width larger than 5{AA} and (2) no measured CaII H/K depression larger than 40%. We subdivide our sample into 426 higher-confidence candidates and 75 lower-confidence candidates.
- ID:
- ivo://CDS.VizieR/J/MNRAS/508/2798
- Title:
- Sample of 102 distant quasars
- Short Name:
- J/MNRAS/508/2798
- Date:
- 04 Mar 2022 14:51:25
- Publisher:
- CDS
- Description:
- We present the radio properties of optically selected quasars with z>=3. The complete sample consists of 102 quasars with a flux density level S_1.4_>=100mJy in a declination range -35{deg}<=Dec.<=+49{deg}. The observations were obtained in 2017-2020 using the radio telescope RATAN-600. We measured flux densities at six frequencies 1.2, 2.3, 4.7, 8.2, 11.2, and 22GHz quasi-simultaneously with uncertainties of 9-31 per cent. The detection rate is 100, 89, and 46 per cent at 4.7, 11.2, and 22GHz, respectively. We have analysed the averaged radio spectra of the quasars based on the RATAN and literature data. We classify 46 per cent of radio spectra as peaked-spectrum, 24 per cent as flat, and none as ultra-steep spectra ({alpha}<=-1.1). The multifrequency data reveal that a peaked spectral shape (PS) is a common feature for bright high-redshift quasars. This indicates the dominance of bright compact core emission and the insignificant contribution of extended optically thin kpc-scale components in observed radio spectra. Using these new radio data, the radio loudness log R was estimated for 71 objects with a median value of 3.5, showing that the majority of the quasars are highly radio-loud with log R>2.5. We have not found any significant correlation between z and {alpha}. Several new megahertz- peaked spectrum (MPS) and gigahertz- peaked spectrum (GPS) candidates are suggested. Further studies of their variability and additional low-frequency observations are needed to classify them precisely.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/68.262
- Title:
- Sample of 467 GPS candidates
- Short Name:
- J/other/AstBu/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a comprehensive analysis of continuous radio spectra of a sample of Gigahertz-Peaked Spectrum (GPS) sources are reported. The sources are selected from a flux-density-complete sample (S more or equal 200mJy at 4.8 or 5GHz) using multifrequency measurements of the RATAN-600 radio telescope and data from the CATS astrophysical catalogs support system. The analysis revealed a very small number (1-2%) of "classical" GPS objects, which is significantly less than the expected fraction of 10%. GPS galaxies are found to have narrower and steeper radio spectra than quasars. The low-frequency part of the spectrum is seen to become steeper with increasing redshift. Galaxies and quasars at the same z have comparable angular sizes, whereas their luminosities may differ by one order of magnitude. At large redshifts there is a deficit of objects with low (several GHz) peak frequencies. The number of GPS galaxies decreases sharply with redshift, and most of them are found at z between 0.01 and 1.81. GPS quasars are found at large redshifts, from 0.11 to 3.99. A quarter of the sample consists of blazars whose spectra may temporarily have a convex shape when the object is in active state.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A36
- Title:
- Sample of weak blazars at mas resolution
- Short Name:
- J/A+A/577/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We started a follow-up investigation of the "Deep X-ray Radio Blazar Survey" objects with declination >-10{deg} to better understand the blazar phenomenon. We undertook a survey with the European Very Long Baseline Interferometry Network at 5GHz to make the first images of a complete sample of weak blazars, aiming at a follow-up comparison between high- and low-power samples of blazars. We observed 87 sources with the EVN at 5GHz during the period October 2009 to May 2013. The observations were correlated at the Max-Planck-Institut fuer Radioastronomie and at the Joint Institute for VLBI in Europe. The correlator output was analysed using both the AIPS and DIFMAP software packages. All of the sources observed were detected. Point-like sources are found in 39 cases on a milli-arcsecond scale, and 48 show core-jet structure. The total flux density distribution at 5GHz has a median value <S>=44^+23^_-10_mJy. A total flux density <=150mJy is observed in 68 out of 87 sources. Their brightness temperature T_b_ ranges between 10^7^K and 10^12^K. According to the spectral indices previously obtained with multi-frequency observations, 58 sources show a flat spectral index, and 29 sources show a steep spectrum or a spectrum peaking at a frequency around 1-2GHz. Adding to the DXRBS objects we observed those already observed with ATCA in the Southern sky, we found that 14 blazars and a Steep Spectrum Radio Quasars, are associated to {gamma}-ray emitters. We found that 56 sources can be considered blazars. We also detected 2 flat spectrum narrow line radio galaxies. About 50% of the blazars associated to a {gamma}-ray object are BLLacs, confirming that they are more likely detected among blazars {gamma}-emitters. We confirm the correlation found between the source core flux density and the {gamma}-ray photon fluxes down to fainter flux densities. We also found that weak blazars are also weaker {gamma}-ray emitters compared to bright blazars. Twenty-two sources are SSRQs or Compact Steep-spectrum Sources, and 7 are GigaHz Peaked Sources. The available X-ray ROSAT observations allow us to suggest that CSS and GPS quasars are not obscured by large column of cold gas surrounding the nuclei. We did not find any significant difference in X-ray luminosity between CSS and GPS quasars.
