- ID:
- ivo://CDS.VizieR/J/A+A/507/131
- Title:
- BzJK observations around radio galaxies
- Short Name:
- J/A+A/507/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the environments of two radio galaxies at z~1.5, 7C 1751+6809 and 7C 1756+6520, using deep optical and near-infrared imaging. Our data cover 15x15arcmin^2^ fields around the radio galaxies. We develop and apply BzK color criteria to select cluster member candidates around the radio galaxies and find no evidence of an overdensity of red galaxies within 2Mpc of 7C 1751+6809. In contrast, 7C 1756+6520 shows a significant overdensity of red galaxies within 2Mpc of the radio galaxy, by a factor of 3.1+/-0.8 relative to the four MUSYC fields. At small separation (r<6"), this radio galaxy also has one z>1.4 evolved galaxy candidate, one z>1.4 star-forming galaxy candidate, and an AGN candidate (at indeterminate redshift).
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/533/744
- Title:
- Calibration of the Tully-Fischer relation
- Short Name:
- J/ApJ/533/744
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The correlation between the luminosities and rotation velocities of galaxies can be used to estimate distances to late-type galaxies. It is an appropriate moment to reevaluate this method given the great deal of new information available. The major improvements described here include: (1) the template relations can now be defined by large, complete samples, (3) the samples are drawn from a wide range of environments, (3) the relations are defined by photometric information at the B, R, I, and K' bands, (4) the multiband information clarifies problems associated with internal reddening, (5) the template zero points are defined by 24 galaxies with accurately known distances, and (6) the relations are applied to 12 clusters scattered across the sky and out to velocities of 8000km/s.
- ID:
- ivo://CDS.VizieR/J/AJ/153/157
- Title:
- Candidate ICRF flat-spectrum radio sources. III.
- Short Name:
- J/AJ/153/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ~160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58m European Southern Observatory New Technology Telescope, and the two 8.2m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A29
- Title:
- 3C388 145, 392, 614, 1400 and 4850MHz images
- Short Name:
- J/A+A/638/A29
- Date:
- 23 Mar 2022 16:29:17
- Publisher:
- CDS
- Description:
- Restarted radio galaxies represent a unique tool to investigate the duty cycle of the jet activity in Active Galactic Nuclei. Due to a sharp discontinuity of the GHz spectral index distribution within its lobes, the radio galaxy 3C388 has for long being claimed to be a peculiar example of AGN with multi-epoch activity The goal of this work is to perform for the first time a spatially resolved study of the radio spectrum of this source down to MHz-frequencies, in order to investigate its radiative age and constrain its duty cycle. We have used new low frequency observations at 144MHz performed with the Low Frequency Array and at 350MHz performed with the Very Large Array combined with archival data at higher frequencies (614, 1400, 4850MHz). Results. We find that the spectral indices in the lower frequency range 144-614MHz have flatter values ({alpha}_low_~0.55-1.14) than those observed in the higher frequency range 1400-4850MHz ({alpha}_high_~0.75-1.57) but follow the same distribution across the lobes, with a systematic steepening towards the edges. However, the spectral shape throughout the source is not uniform and often deviates from standard models. This suggests that mixing of different particle populations is occurring, although it remains difficult to understand whether this is caused by observational limitations (insufficient spatial resolution and/or projection effects) or by the intrinsic presence of multiple particle populations, possibly related to the two different outbursts. By using single-injection radiative models we compute that the total source age is <~80Myr and that the duty cycle is about t_on_/t_tot_~60%, which is enough to prevent the intracluster medium from cooling according to X-ray estimates. While to date the radio spectral distribution of 3C388 remains a rare case among radio galaxies, multi-frequency surveys performed with new generation instruments will soon allow us to investigate whether more sources with the same characteristics do actually exist.
- ID:
- ivo://CDS.VizieR/J/MNRAS/496/2663
- Title:
- Canes Venatici I images with LOFAR
- Short Name:
- J/MNRAS/496/2663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dwarf galaxies are dark matter-dominated and therefore promising targets for the search for weakly interacting massive particles (WIMPs), which are well-known candidates for dark matter. Annihilation of WIMPs produce ultra-relativistic cosmic-ray electrons and positrons that emit synchrotron radiation in the presence of magnetic fields. For typical magnetic field strengths (few G) and O(GeV-TeV) WIMP masses (and thus typical electron energies of the same order) this emission peaks at hundreds of MHz. Here, we use the non-detection of 150-MHz radio continuum emission from the dwarf spheroidal galaxy 'Canes Venatici I' with the LOw-Frequency ARray (LO-FAR) to derive constraints on the annihilation cross section of WIMPs into primary electron-positron and other fundamental particle-antiparticle pairs. In this first-of-its-kind LOFAR study, we obtain new constraints on annihilating WIMP dark matter (DM). Using conservative estimates for the magnetic field strengths and diffusion coefficients, we obtain limits that are comparable with those by the Fermi Large Area Telescope (Fermi-LAT) using gamma-ray observations. Assuming s-wave annihilation and WIMPs making up 100% of the DM density, our limits exclude several thermal WIMP realisations in the [2, 20]-GeV mass range. A more ambitious multi-wavelength and multi-target LOFAR study could improve these limits by a few orders of magnitude.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A22
- Title:
- CARLA J1103+3449 cluster datacube
- Short Name:
- J/A+A/641/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Passive early-type galaxies dominate cluster cores at z<~1.5. At higher redshift, cluster core galaxies are observed to have on-going star-formation, which is fuelled by cold molecular gas.We measured the molecular gas reservoir of the central region around the radioloud active galactic nucleus (AGN) in the cluster CARLA J1103+3449 at z=1.44 using NOEMA. The AGN synchrotron emission dominates the continuum emission at 94.48GHz, and we measured its flux at the AGN position and at the position of two radio jets. Combining our measurements with published results over the range 4.71GHz-94.5GHz, and assuming S_synch_{prop.to}{nu}^-{alpha}^, we obtain a flat spectral index of = 0:14 0:03 for the AGN core emission, and a steeper index of {alpha}=1.43+/-0.04 and {alpha}=1.15+/-0.04 at positions close to the western and eastern lobes, respectively. The total spectral index is {alpha}=0.92+/-0.02 over the range 73.8MHz-94.5GHz.We detect two CO(2-1) emission lines, both blueshifted with respect to the AGN. Their emission corresponds to two regions, 17kpc southeast and 14kpc southwest of the AGN, not associated with galaxies. In these two regions, we find a total massive molecular gas reservoir of M^tot^_gas_=3.9+/-0.4x10^10^M_{sun}_, which dominates (>~60%) the central total molecular gas reservoir. These results can be explained by massive cool gas flows in the center of the cluster. The AGN early-type host is not yet quenched; its star formation rate is consistent with being on the main sequence of star-forming galaxies in the field (star formation rate ~30-140M_[sun}_/yr), and the cluster core molecular gas reservoir is expected to feed the AGN and the host star formation before quiescence. The other confirmed cluster members show star formation rates at 2 below the field main sequence at similar redshifts and do not have molecular gas masses larger than galaxies of similar stellar mass in the field.
- ID:
- ivo://CDS.VizieR/J/AJ/154/152
- Title:
- CARMA 1 cm spectral line survey of Orion-KL
- Short Name:
- J/AJ/154/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orion-KL is a well-known high-mass star-forming region that has long been the target of spectral line surveys and searches for complex molecules. One spectral window where the region had never been surveyed is around wavelengths of {lambda}=1 cm. This is an important window to observe, due to the fundamental and low energy transitions of numerous complex molecules that indicate the maximum spatial extent of the molecular species; knowing the spatial distribution of a molecule aids in determining the formation mechanism(s) of that molecule. Additionally, there are fewer transitions in this window, reducing confusion caused by blended lines that can be very problematic at shorter wavelengths ({lambda}<3 mm). In this work, we present the first spectral line survey at {lambda}=1 cm of the Orion-KL region. A total of 89 transitions were detected from 14 molecular species and isotopologues, and two atomic species. The observations were conducted with the Combined Array for Research in Millimeter-wave Astronomy in both interferometric and single dish modes.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A110
- Title:
- Cas A LOFAR and VLA images
- Short Name:
- J/A+A/612/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cassiopeia A is one of the best-studied supernova remnants. Its bright radio and X-ray emission is due to shocked ejecta. Cas A is rather unique in that the unshocked ejecta can also be studied: through emission in the infrared, the radio-active decay of ^44^Ti, and the low-frequency free-free absorption caused by cold ionised gas, which is the topic of this paper. Free-free absorption processes are acted by the mass, geometry, temperature, and ionisation conditions in the absorbing gas. Observations at the lowest radio frequencies can constrain a combination of these properties. We used Low Frequency Array (LOFAR) Low Band Antenna observations at 30-77MHz and Very Large Array (VLA) L-band observations at 1-2GHz to fit for internal absorption as parametrised by the emission measure. We simultaneously fit multiple UV-matched images with a common resolution of 17" (this corresponds to 0.25pc for a source at the distance of Cas A). The ample frequency coverage allows us separate the relative contributions from the absorbing gas, the unabsorbed front of the shell, and the absorbed back of the shell to the emission spectrum. We explored the effects that a temperature lower than the ~100-500K proposed from infrared observations and a high degree of clumping can have on the derived physical properties of the unshocked material, such as its mass and density. We also compiled integrated radio flux density measurements, fit for the absorption processes that occur in the radio band, and considered their ect on the secular decline of the source. We find a mass in the unshocked ejecta of M=2.95+/-0.48M_{sun}_ for an assumed gas temperature of T=100K. This estimate is reduced for colder gas temperatures and, most significantly, if the ejecta are clumped.We measure the reverse shock to have a radius of 114+/-6" and be centred at 23:23:26, +58:48:54 (J2000).We also find that a decrease in the amount of mass in the unshocked ejecta (as more and more material meets the reverse shock and heats up) cannot account for the observed low-frequency behaviour of the secular decline rate. To reconcile our low-frequency absorption measurements with models that reproduce much of the observed behaviour in Cas A and predict little mass in the unshocked ejecta, the ejecta need to be very clumped or the temperature in the cold gas needs to be low (~10K). Both of these options are plausible and can together contribute to the high absorption value that we find.
- ID:
- ivo://CDS.VizieR/J/AZh/84/579
- Title:
- Catalog of Class I methanol masers
- Short Name:
- J/AZh/84/579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of class I methanol masers discovered so far in the Southern and Northern hemispheres is presented. The catalog contains 160 sources. A statistical analysis shows that, within 2' of the telescope pointing (which corresponds approximately to the field of view of single antennas used in search surveys), 50% of class I methanol masers are associated with objects characteristic of active starforming regions: IRAS sources, ultracompact HII regions, and dense gas dust clouds, as well as OH and H2O interstellar masers. At the same time, bipolar out flows (which could play an active part in pumping the methanol masers) are associated with fewer than 25% of class I methanol masers. In 72% of cases, class I methanol masers are associated with class II methanol maser sources. These results suggest that methanol maser condensations are more appropriately classified by the transition type (that is, the pumping mechanism) than their association with other astronomical objects.
- ID:
- ivo://CDS.VizieR/VIII/94
- Title:
- Catalog of extended extragalactic radio sources
- Short Name:
- VIII/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of extended extragalactic radio sources consisting of 10460 objects is compiled based on the list of radio sources of the FIRST survey. A total of 2339 objects are identified with galaxies and quasars of the SDSS survey and the Veron-Veron catalog. The distribution of position angles of the axes of radio sources from the catalog is determined, and the probability that this distribution is equiprobable is shown to be less than 10^-7^. This result implies that at Z equal to or smaller than 0.5, the spatial orientation of the axes of radio sources is anisotropic at a statistically significant level.