- ID:
- ivo://CDS.VizieR/J/MNRAS/246/169
- Title:
- Radio continuum around G 73.9+0.9
- Short Name:
- J/MNRAS/246/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A field centered on the galactic supernova remnant (SNR) G073.9+00.9 was mapped in the continuum at 408 and 1420 MHz with the Dominion Radio Astrophysical Observatory (DRAO). The interferometer observations, of resolution 3.4x5.8 arcmin^2^ and 1.0x1.7 arcmin^2^ respectively, were complemented with single-dish data so that the resulting maps are sensitive to all structures down to the synthesized beam. Note that this list is part of the DRAO Penticton P-survey Database (Catalog <VIII/55>)
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- ID:
- ivo://CDS.VizieR/J/MNRAS/455/4191
- Title:
- Radio emission from radio-quiet quasars
- Short Name:
- J/MNRAS/455/4191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio emission from radio-quiet quasars may be due to star formation in the quasar host galaxy, to a jet launched by the supermassive black hole, or to relativistic particles accelerated in a wide-angle radiatively driven outflow. In this paper, we examine whether radio emission from radio-quiet quasars is a byproduct of star formation in their hosts. To this end, we use infrared spectroscopy and photometry from Spitzer and Herschel to estimate or place upper limits on star formation rates in hosts of ~300 obscured and unobscured quasars at z<1. We find that low-ionization forbidden emission lines such as [NeII] and [NeIII] are likely dominated by quasar ionization and do not provide reliable star formation diagnostics in quasar hosts, while polycyclic aromatic hydrocarbon (PAH) emission features may be suppressed due to the destruction of PAH molecules by the quasar radiation field. While the bolometric luminosities of our sources are dominated by the quasars, the 160{mu}m fluxes are likely dominated by star formation, but they too should be used with caution. We estimate median star formation rates to be 6-29M_{sun}_/yr, with obscured quasars at the high end of this range. This star formation rate is insufficient to explain the observed radio emission from quasars by an order of magnitude, with log(L_radio,obs_/L_radio,SF_)=0.6-1.3 depending on quasar type and star formation estimator. Although radio-quiet quasars in our sample lie close to the 8-1000{mu}m infrared/radio correlation characteristic of the star-forming galaxies, both their infrared emission and their radio emission are dominated by the quasar activity, not by the host galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A19
- Title:
- Radio-farIR correlation in NGC 6946
- Short Name:
- J/A+A/552/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive the distribution of the synchrotron spectral index across NGC 6946 and investigate the correlation between the radio continuum (synchrotron) and far-infrared (FIR) emission using the KINGFISH Herschel PACS and SPIRE data.
- ID:
- ivo://CDS.VizieR/J/ApJS/166/567
- Title:
- Radio Molecular lines in infrared dark clouds
- Short Name:
- J/ApJS/166/567
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 41 infrared dark clouds from the 8um maps of the Midcourse Space Experiment (MSX), selected to be found within 1deg^2^ areas centered on known ultracompact HII regions. We have mapped these infrared dark clouds in N_2_H^+^ 1->0, CS 2->1, and C^18^O 1->0 emission using the Five College Radio Astronomy Observatory. The maps of the different species often show striking differences in morphologies, indicating differences in evolutionary state and/or the presence of undetected, deeply embedded protostars. We derive an average mass for these clouds using N_2_H^+^ column densities of >>2500M_{sun}_, a value comparable to that found in previous studies of high-mass star-forming cores using other mass tracers. The line widths of these clouds are typically 2.0-2.9km/s. Based on the fact that they are dark at 8um, compact, and massive, and have large velocity dispersions, we suggest that these clouds may be the precursor sites of intermediate- and high-mass star formation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/479
- Title:
- Radio obs. of optically obscured galaxies
- Short Name:
- J/MNRAS/383/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper analyses the radio properties of a subsample of optically obscured (R>=25.5) galaxies observed at 24um by the Spitzer Space Telescope within the First Look Survey. Ninety-six F24um>=0.35mJy objects out of 510 are found to have a radio counterpart at 1.4GHz, 610MHz or at both frequencies, respectively, down to ~40 and ~200uJy. IRAC photometry sets the majority of them in the redshift interval z~=[1-3] and allows for a broad distinction between active galactic nucleus (AGN) dominated galaxies (~47 per cent of the radio-identified sample) and systems powered by intense star formation (~13 per cent), the remaining objects being impossible to classify. The percentage of radio identifications is a strong function of 24-um flux: almost all sources brighter than F_24um_~2mJy are endowed with a radio flux at both 1.4GHz and 610MHz, while this fraction drastically decreases by lowering the 24-um flux level.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/48
- Title:
- Radio & opt/NIR counterparts of S2COSMOS submm galaxies
- Short Name:
- J/ApJ/886/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify multi-wavelength counterparts to 1147 submillimeter sources from the S2COSMOS SCUBA-2 survey of the COSMOS field by employing a recently developed radio+machine-learning method trained on a large sample of Atacama Large Millimeter/submillimeter Array (ALMA)-identified submillimeter galaxies (SMGs), including 260 SMGs identified in the AS2COSMOS pilot survey. In total, we identify 1222 optical/near-infrared (NIR)/radio counterparts to the 897 S2COSMOS submillimeter sources with S_850_>1.6mJy, yielding an overall identification rate of (78+/-9)%. We find that (22+/-5)% of S2COSMOS sources have multiple identified counterparts. We estimate that roughly 27% of these multiple counterparts within the same SCUBA-2 error circles very likely arise from physically associated galaxies rather than line-of-sight projections by chance. The photometric redshift of our radio+machine-learning-identified SMGs ranges from z=0.2 to 5.7 and peaks at z=2.3+/-0.1. The AGN fraction of our sample is (19+/-4)%, which is consistent with that of ALMA SMGs in the literature. Comparing with radio/NIR-detected field galaxy population in the COSMOS field, our radio+machine-learning-identified counterparts of SMGs have the highest star formation rates and stellar masses. These characteristics suggest that our identified counterparts of S2COSMOS sources are a representative sample of SMGs at z<~3. We employ our machine-learning technique to the whole COSMOS field and identified 6877 potential SMGs, most of which are expected to have submillimeter emission fainter than the confusion limit of our S2COSMOS surveys (S_850um_<~1.5mJy). We study the clustering properties of SMGs based on this statistically large sample, finding that they reside in high-mass dark matter halos ((1.2+/-0.3)x10^13^h^-1^M_{sun}_), which suggests that SMGs may be the progenitors of massive ellipticals we see in the local universe.
- ID:
- ivo://CDS.VizieR/J/AJ/102/1663
- Title:
- Radio properties of extragal. IRAS sources
- Short Name:
- J/AJ/102/1663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog presents radio and optical identifications of extragalactic IRAS sources from the IRAS Faint Source Catalog |b| > 50{deg} (Moshir et al., 1989 Cat. <II/156>). Sources with flux density > 0.2 at 60 microns and with S_60_ > S_12_ were identified by position coincidence with radio sources stronger than 25 mJy and lying north of declination = 5{deg} on the Green Bank 4.85 GHz sky map. Published VLA maps, new 4.86 GHz VLA maps made with 15 arcsec resolution, and accurate optical positions were used to confirm 122 candidate identifications. This catalog contains a merged version of tables 1 and 2 from the paper.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A131
- Title:
- Radio survey of ultracool dwarfs
- Short Name:
- J/A+A/549/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to increase the sample of ultracool dwarfs studied in the radio domain to allow a more statistically significant understanding of the physical conditions associated with these magnetically active objects. We conducted a volume-limited survey at 4.9GHz of 32 nearby ultracool dwarfs with spectral types covering the range M7-T8. A statistical analysis was performed on the combined data from the present survey and previous radio observations of ultracool dwarfs.
- ID:
- ivo://CDS.VizieR/J/AJ/162/72
- Title:
- Random forests method to discover high-redshift QSOs
- Short Name:
- J/AJ/162/72
- Date:
- 14 Mar 2022 07:01:17
- Publisher:
- CDS
- Description:
- We present a method of selecting quasars up to redshift ~6 with random forests, a supervised machine-learning method, applied to Pan-STARRS1 and WISE data. We find that, thanks to the increasing set of known quasars, we can assemble a training set that enables supervised machine-learning algorithms to become a competitive alternative to other methods up to this redshift. We present a candidate set for the redshift range 4.8-6.3, which includes the region around z=5.5 where selecting quasars is difficult due to their photometric similarity to red and brown dwarfs. We demonstrate that, under our survey restrictions, we can reach a high completeness (66%{+/-}7% below redshift 5.6/83_-9_^+6^% above redshift 5.6) while maintaining a high selection efficiency (78_-8_^+10^%/94_-8_^+5^% ). Our selection efficiency is estimated via a novel method based on the different distributions of quasars and contaminants on the sky. The final catalog of 515 candidates includes 225 known quasars. We predict the candidate catalog to contain additional 148_-33_^+41^ new quasars below redshift 5.6 and 45_-8_^+5^ above, and we make the catalog publicly available. Spectroscopic follow-up observations of 37 candidates led us to discover 20 new high redshift quasars (18 at 4.6<~z<~5.5, 2z~5.7). These observations are consistent with our predictions on efficiency. We argue that random forests can lead to higher completeness because our candidate set contains a number of objects that would be rejected by common color cuts, including one of the newly discovered redshift 5.7 quasars.
- ID:
- ivo://CDS.VizieR/J/A+A/350/883
- Title:
- R CrA ISOCAM observations
- Short Name:
- J/A+A/350/883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of an ISOCAM survey of the R CrA star formation region are presented. The survey was carried out in two broad-band filters, LW2 (5-8.5{mu}m) and LW3 (12-18{mu}m). Although it was not possible to map the densest, central region due to saturation problems, 21 sources were identified which showed mid-IR excesses. Most of these sources have not previously been recognised as YSOs (Young Stellar Objects), mainly because they are relatively faint. We find evidence for a population of very low mass stars which are probably brown dwarfs in their early contraction phases.
