- ID:
- ivo://CDS.VizieR/J/MNRAS/392/1403
- Title:
- GMRT radios sources around J0916+6348 field
- Short Name:
- J/MNRAS/392/1403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep multifrequency observations using the Giant Metrewave Radio Telescope (GMRT) at 153, 244, 610 and 1260MHz of a field centred on J0916+6348, to search for evidence of fossil radio lobes which could be due to an earlier cycle of episodic activity of the parent galaxy, as well as haloes and relics in clusters of galaxies. We do not find any unambiguous evidence of episodic activity in a list of 374 sources, suggesting that such activity is rare even in relatively deep low-frequency observations. We examine the spectra of all the sources by combining our observations with those from the Westerbork Northern Sky Survey (WENSS), NRAO (National Radio Astronomy Observatories) VLA (Very Large Array) Sky Survey (NVSS) and the Faint Images of the Radio Sky at Twenty-Centimeters Survey (FIRST).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/622/A196
- Title:
- GMVA 86GHz Stokes IQU images of 3C84 jet
- Short Name:
- J/A+A/622/A196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results from a deep polarization imaging of the nearby radio galaxy 3C 84 (NGC 1275). The source was observed with the Global Millimeter VLBI Array (GMVA) at 86GHz at an ultrahigh angular resolution of 50{mu}as (corresponding to 200Rs). We also add complementary multiwavelength data from the Very Long Baseline Array (VLBA; 15 & 43GHz) and from the Atacama Large Millimeter/submillimeter Array (ALMA; 97.5, 233.0, and 343.5GHz). At 86GHz, we measured a fractional linear polarization of ~2% in the VLBI core region. The polarization morphology suggests that the emission is associated with an underlying limb-brightened jet. The fractional linear polarization is lower at 43 and 15GHz (~0.3-0.7% and <0.1%, respectively). This suggests an increasing linear polarization degree toward shorter wavelengths on VLBI scales. We also obtain a large rotation measure (RM) of ~10^5-6^rad/m^2^ in the core at >~43GHz. Moreover, the VLBA 43GHz observations show a variable RM in the VLBI core region during a small flare in 2015. Faraday depolarization and Faraday conversion in an inhomogeneous and mildly relativistic plasma could explain the observed linear polarization characteristics and the previously measured frequency dependence of the circular polarization. Our Faraday depolarization modeling suggests that the RM most likely originates from an external screen with a highly uniform RM distribution. To explain the large RM value, the uniform RM distribution, and the RM variability, we suggest that the Faraday rotation is caused by a boundary layer in a transversely stratified jet. Based on the RM and the synchrotron spectrum of the core, we provide an estimate for the magnetic field strength and the electron density of the jet plasma.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A48
- Title:
- GOODS-N AGN VLBI detect. & radio properties
- Short Name:
- J/A+A/619/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Conventional radio surveys of deep fields ordinarily have arc-second scale resolutions often insufficient to reliably separate radio emission in distant galaxies originating from star-formation and AGN-related activity. Very long baseline interferometry (VLBI) can offer a solution by identifying only the most compact radio emitting regions in galaxies at cosmological distances where the high brightness temperatures (in excess of 10^5^K) can only be reliably attributed to AGN activity.The newest VLBI techniques are used to completely cover an entire 7.5' radius area to milliarcsecond resolutions, while bright radio sources (S>0.1mJy) are targeted up to 25-arcmin from the pointing centre. Multi-source self-calibration, and a primary beam model for the EVN array are used to correct for residual phase errors and primary beam attenuation respectively. This paper presents the largest catalogue of VLBI detected sources in GOODS-N comprising of 31 compact radio sources across a redshift range of 0.11-3.44, almost three times more than previous VLBI surveys in this field.
- ID:
- ivo://CDS.VizieR/J/MNRAS/405/2260
- Title:
- GOODS-S field AzTEC/ASTE Deep 1.1mm imaging
- Short Name:
- J/MNRAS/405/2260
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from a 1.1mm confusion-limited map of the Great Observatories Origins Deep Survey-South (GOODS-S) taken with the AzTEC camera on the Atacama Submillimeter Telescope Experiment. We imaged 270arcmin^2^ field to a 1{sigma} depth of 0.48-0.73mJy/beam, making this one of the deepest blank-field surveys at mm-wavelengths ever achieved. Although by traditional standards our GOODS-S map is extremely confused due to a sea of faint underlying sources, we demonstrate through simulations that our source identification and number counts analyses are robust, and the techniques discussed in this paper are relevant for other deeply confused surveys. We find a total of 41 dusty starburst galaxies with signal-to-noise ratios S/N>=3.5 within this uniformly covered region, where only two are expected to be false detections, and an additional seven robust source candidates located in the noisier (1{sigma}~1mJy/beam) outer region of the map.
- ID:
- ivo://CDS.VizieR/J/A+A/569/A68
- Title:
- Green Bank Telescope observations of NGC 2403
- Short Name:
- J/A+A/569/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observed HI accretion around nearby galaxies can only account for a fraction of the gas supply needed to sustain the currently observed star formation rates. It is possible that additional accretion happens in the form of low column density cold flows, as predicted by numerical simulations of galaxy formation. To contrain the presence and properties of such flows, we present deep HI observations obtained with the NRAO Green Bank Telescope of an area measuring 4 by 4 degrees around NGC 2403. These observations, with a 5{sigma} detection limit of 2.4x10^18^cm^-2^ over a 20km/s linewidth, reveal the presence of a low-column density, extended cloud outside the main HI disk, about 17' (~16kpc or ~2R_25_) to the NW of the center of the galaxy. The total HI mass of the cloud is 6.3x10^6^M_{sun}_, or 0.15% of the total HI mass of NGC 2403. The cloud is associated with an 8kpc anomalous-velocity HI filament in the inner disk, previously observed in deep VLA observations by Fraternali et al. (2001ApJ...562L..47F, 2002AJ....123.3124F). We discuss several scenarios for the origin of the cloud, and conclude that it is either accreting from the intergalactic medium, or is the result of a minor interaction with a neigbouring dwarf galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A48
- Title:
- HAE229 CO (1-0) ATCA datacube
- Short Name:
- J/A+A/608/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is not yet known if the properties of molecular gas in distant protocluster galaxies are significantly acted by their environment as galaxies are in local clusters. Through a deep, 64 hours of effective on-source integration with the Australian Telescope Compact Array (ATCA), we discovered a massive, M_mol_=2.0+/-0.2x0^11^M_{sun}_, extended, ~40kpc, CO(1-0)-emitting disk in the protocluster surrounding the radio galaxy, MRC1138-262. The galaxy, at z_CO_=2.1478, is a clumpy, massive disk galaxy, M*~5x10^11^M_{sun}_, which lies 250kpc in projection from MRC1138-262 and is a known H{alpha} emitter, named HAE229. This source has a molecular gas fraction of ~30%. The CO emission has a kinematic gradient along its major axis, centered on the highest surface brightness rest-frame optical emission, consistent with HAE229 being a rotating disk. Surprisingly, a significant fraction of the CO emission lies outside of the UV/optical emission. In spite of this, HAE229 follows the same relation between star-formation rate and molecular gas mass as normal field galaxies. HAE229 is the first CO(1-0) detection of an ordinary, star-forming galaxy in a protocluster.We compare a sample of cluster members at z>0.4 that are detected in low-order CO transitions, with a similar sample of sources drawn from the field.We confirm findings that the CO-luminosity and full-width at half maximum (FWHM) are correlated in starbursts and show that this relation is valid for normal high-z galaxies as well as for those in overdensities. We do not find a clear dichotomy in the integrated Schmidt-Kennicutt relation for protocluster and field galaxies. Our results suggest that environment does not have an impact on the "star-formation electronic efficiency" or the molecular gas content of high-redshift galaxies. Not finding any environmental dependence in these characteristics, especially for such an extended CO disk, suggests that environmentally-specific processes such as ram pressure stripping do not operate electronic efficiently in (proto)clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/1977
- Title:
- H-alpha emitters in/towards USS 1558
- Short Name:
- J/MNRAS/473/1977
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out deep H{alpha} narrowband imaging with 10h net integrations towards the young protocluster, USS1558-003 at z=2.53 with the Subaru Telescope. This system is composed of four dense groups with massive local overdensities, traced by 107 H{alpha} emitters (HAEs) with stellar masses and dust-corrected star formation rates down to 1x10^8^M_{sun}_ and 3M_{sun}_/yr, respectively. We have investigated the environmental dependence of various physical properties within the protocluster by comparing distributions of HAEs in higher and lower densities with a standard Kolmogorov-Smirnov test. At 97 per cent confidence level, we find enhanced star formation across the star-forming main sequence of HAEs living in the most extreme 'supergroup', corresponding to the top quartile of overdensities. Furthermore, we derive distribution functions of H{alpha} luminosity and stellar mass in group and intergroup regions, approximately corresponding to 30 and 8 times higher densities than the general field. As a consequence, we identify 0.7 and 0.9dex higher cut-offs in H{alpha} luminosity and stellar mass functions in the dense groups, respectively. On the other hand, HAEs in the intergroup environment of the protocluster show similar distribution functions to those of field galaxies despite residing in significant overdensities. In the early phase of cluster formation, as inferred from our results, the densest parts in the protocluster have had an accelerated formation of massive galaxies. We expect that these eventually grow and transform into early-type galaxies at the bright end of the red sequence as seen in present-day rich clusters of galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A118
- Title:
- HCN(1-0) cube for the nucleus of M51
- Short Name:
- J/A+A/593/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AGN feedback is invoked as one of the most relevant mechanisms that shape the evolution of galaxies. Our goal is to understand the interplay between AGN feedback and the interstellar medium in M51, a nearby spiral galaxy with a modest AGN and a kpc-scale radio jet expanding through the disc of the galaxy. For that, we combine molecular gas observations in the CO(1-0) and HCN(1-0) lines from the Plateau de Bure interferometer with archival radio, X-ray, and optical data. We show that there is a significant scarcity of CO emission in the ionisation cone, while molecular gas emission tends to accumulate towards the edges of the cone. The distribution and kinematics of CO and HCN line emission reveal AGN feedback effects out to r~500pc, covering the whole extent of the radio jet, with complex kinematics in the molecular gas which displays strong local variations. We propose that this is the result of the almost coplanar jet pushing on molecular gas in different directions as it expands; the effects are more pronounced in HCN than in CO emission, probably as the result of radiative shocks. Following previous interpretation of the redshifted molecular line in the central 5" as caused by a molecular outflow, we estimate the outflow rates to be Mdot_H2~0.9M_{sun}_/yr and dM/dt_dense_~0.6M_{sun}_/yr, which are comparable to the molecular inflow rates (~1M_{sun}_/yr); gas inflow and AGN feedback could be mutually regulated processes. The agreement with findings in other nearby radio galaxies suggests that this is not an isolated case, and probably the paradigm of AGN feedback through radio jets, at least for galaxies hosting low-luminosity active nuclei.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A5
- Title:
- Hercules A LOFAR and JVLA images
- Short Name:
- J/A+A/658/A5
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The prominent radio source Hercules A features complex structures in its radio lobes. Despite being one of the most comprehensively studied sources in the radio sky, the origin of the ring structures in the Hercules A radio lobes remains an open question. We present the first sub-arcsecond angular resolution images at low frequencies (<300MHZ) of Hercules A, made with the International LOFAR Telescope. With the addition of data from the Karl G. Jansky Very Large Array, we map the structure of the lobes from 144MHz to 7GHz. We explore the origin of the rings within the lobes of Hercules A, and test whether their properties are best described by a shock model where shock waves are produced by the jet propagating in the radio lobe, or an inner-lobe model in which the rings are formed by decelerated jetted plasma. From spectral index mapping, our large frequency coverage reveals that the curvature of the different ring spectra increases with distance away from the central active galactic nucleus. We demonstrate that the spectral shape of the rings is consistent with synchrotron aging, which speaks in favor of an inner-lobe model, where the rings are formed from the deposition of material from past periods of intermittent core activity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/409/L13
- Title:
- Herschel-SPIRE radio galaxies
- Short Name:
- J/MNRAS/409/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first study of the far-infrared (FIR) properties of high-redshift, radio-selected ultraluminous infrared galaxies (ULIRGs) using deep observations obtained with the Spectral and Photometric Imaging Receiver (SPIRE) from the Herschel Multi-tiered Extragalactic Survey (HerMES). These galaxies span a large range of 850-um fluxes from submillimetre-luminous ~10mJy sources (SCUBA galaxies) to ~1.5mJy from stacked SCUBA non-detections, thus likely representing a complete distribution of ULIRG spectral energy distributions (SEDs). From Keck spectroscopic surveys in the Lockman-North field we identified a sample of 31 submillimetre galaxies (SMGs) and 37 submillimetre-faint, optically faint radio galaxies (OFRGs), all with radio-inferred IR luminosities >10^12^L_{sun}_. These galaxies were cross-identified with SPIRE 250-, 350- and 500-um catalogues based on fluxes extracted at 24-um positions in the SWIRE survey, yielding a sample of more than half of the galaxies well detected in at least two of the SPIRE bandpasses.
