- ID:
- ivo://CDS.VizieR/J/MNRAS/355/44
- Title:
- ATCA SMC Radio Continuum Source. II.
- Short Name:
- J/MNRAS/355/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the classification of 717 radio-continuum sources from the Australia Telescope Compact Array (ATCA) Catalogue of the Small Magellanic Cloud (SMC). All 717 sources have been categorised into one of three groups: supernova remnants (SNRs), HII regions and background sources. In total, we name 71 sources as HII regions (or candidates) and 21 sources as SNRs (or candidates). Six sources are named as either HII regions or background sources and two are candidate radio planetary nebulae. One source is coincident with an X-ray binary. We classify 616 objects as background sources and present their statistics.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/3969
- Title:
- ATCA Survey of Sagittarius B2 at 7mm
- Short Name:
- J/MNRAS/452/3969
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 30-50GHz survey of Sagittarius B2(N) conducted with the Australia Telescope Compact Array (ATCA) with 5 - 10 arcsec resolution. We analyze the spectra towards three HII regions that have foreground molecular gas in Sgr B2. Towards the most line-dense region, we detect >500 spectral line components, >90% of which are assigned to H and He recombination lines and 53 firmly identified molecular species (not including isotopologues). The data reveal extremely subthermally excited molecular gas in Sgr B2 absorbing against the continuum background, as well as molecular line emission from two hot cores in Sgr B2(N). They also also contain line-of-sight absorption by ~15 molecules observed in translucent gas in the Galactic Center, bar, and intervening spiral arm clouds, revealing the complex chemistry and clumpy structure of this gas. Formamide (NH_2_CHO) is detected for the first time in a translucent cloud.
- ID:
- ivo://CDS.VizieR/J/A+AS/124/509
- Title:
- ATCA/VLA OH 1612 MHz survey. II.
- Short Name:
- J/A+AS/124/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of the region between -45{deg}<=l<=-10{deg} and |b|<=3{deg} in the OH 1612.231MHz line, taken in 1994 January with the Australia Telescope Compact Array (ATCA). These observations are part of a larger survey, covering |l|<=45{deg} and |b|<=3{deg}, with the ATCA and the Very Large Array. In a previous article we have discussed the observational strategy in detail. In this paper we present only the objects found in this part of the survey. The region was systematically searched for OH-maser emission and was covered completely with 910 pointing centres separated by 30'. We found 202 OH-masing objects, 112 of which are new detections. Out of the 202 objects, 166 have a standard double-peaked spectral profile, 32 a single-peaked profile and 4 objects have non-standard or irregular profiles. In this article we analyse the data statistically and give classifications and identifications with known sources where possible. The astrophysical, kinematical, morphological and dynamical properties of subsets of the data will be addressed in future articles.
- ID:
- ivo://CDS.VizieR/J/A+A/366/481
- Title:
- ATCA/VLA OH 1612 MHz survey. III.
- Short Name:
- J/A+A/366/481
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of the region between 5{deg}<=l<=45{deg} and |b|<=3{deg}, in the OH 1612.231MHz line, taken from 1993 to 1995 with NRAO's Very Large Array (VLA). These observations are the last part of a larger survey, covering |l|<=45{deg} and |b|<=3{deg}, with the Australia Telescope Compact Array (ATCA) and the VLA. The region was systematically observed on a 30'x30' grid in (l,b) and the resulting coverage was 92%, with 965 pointings. We found 286 OH-masing objects, 161 of which are new detections and 207 have reliable IRAS point-source identifications. The outflow velocity was determined for 276 sources. A total of 766 sources were detected in the combined ATCA/VLA survey, of which 29 were detected in two regions of the survey.
- ID:
- ivo://CDS.VizieR/J/A+A/457/517
- Title:
- ATESP 5 GHz radio survey. I.
- Short Name:
- J/A+A/457/517
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nature and evolutionary properties of the faint radio population, responsible for the steepening observed in the 1.4GHz source counts below 1mJy, are not yet entirely clear. Radio spectral indices may help to constrain the origin of the radio emission in such faint radio sources and may be fundamental in understanding eventual links to the optical light. We study the spectral index behaviour of sources that were found in the 1.4GHz ATESP survey (Prandoni et al., 2000A&AS..146...31P & 2000, Cat. <VIII/63>), considering that the ATESP is one of the most extensive sub-mJy surveys existing at present. Using the Australia Telescope Compact Array we observed at 5GHz part of the region covered by the sub-mJy ATESP survey. In particular we imaged a one square degree area for which deep optical imaging in UBVRIJK is available. In this paper we present the 5GHz survey and source catalogue, we derive the 5GHz source counts and we discuss the 1.4-5GHz spectral index properties of the ATESP sources. The analysis of the optical properties of the sample will be the subject of a following paper.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A19
- Title:
- ATESP 5 GHz radio survey. IV.
- Short Name:
- J/A+A/621/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is now established that the faint radio population is a mixture of star-forming galaxies and faint active galactic nuclei (AGNs), with the former dominating below S_1.4GHz_~100uJy and the latter at larger flux densities. The faint radio AGN component can itself be separated into two main classes, mainly based on the host-galaxy properties: sources associated with red/early-type galaxies (like radio galaxies) are the dominant class down to ~100uJy; quasar/Seyfert-like sources contribute an additional 10-20%. One of the major open questions regarding faint radio AGNs is the physical process responsible for their radio emission. This work aims at investigating this issue, with particular respect to the AGN component associated with red/early-type galaxies. Such AGNs show, on average, flatter radio spectra than radio galaxies and are mostly compact (<=30kpc in size). Various scenarios have been proposed to explain their radio emission. For instance they could be core/core-jet dominated radio galaxies, low-power BL LACs, or advection dominated accretion flow (ADAF) systems. We used the Australia Telescope Compact Array (ATCA) to extend a previous follow-up multi-frequency campaign to 38 and 94GHz. This campaign focuses on a sample of 28 faint radio sources associated with early-type galaxies extracted from the ATESP 5GHz survey. Such data, together with those already at hand, are used to perform radio spectral and variability analyses. Both analyses can help us to disentangle between core- and jet-dominated sources, as well as to verify the presence of ADAF/ADAF+jet systems. Additional high-resolution observations at 38GHz were carried out to characterise the radio morphology of these sources on kiloparsec scales. Most of the sources (25/28) were detected at 38GHz, while only one (ATESP5J224547-400324) of the twelve sources observed at 94 GHz was detected. From the analysis of the radio spectra we confirmed our previous findings that pure ADAF models can be ruled out. Only eight out of the 28 sources were detected in the 38-GHz high-resolution (0.6 arcsec) radio images and of those eight only one showed a tentative core-jet structure. Putting together spectral, variability, luminosity, and linear size information we conclude that different kinds of sources compose our AGN sample: (a) luminous and large (>=100kpc) classical radio galaxies (~18% of the sample); (b) compact (confined within their host galaxies), low-luminosity, power-law (jet-dominated) sources (~46% of the sample); and (c) compact, flat (or peaked) spectrum, presumably core-dominated, radio sources (~36% of the sample). Variability is indeed preferentially associated with the latter.
- ID:
- ivo://CDS.VizieR/J/MNRAS/434/956
- Title:
- AT20G high-angular-resolution catalogue
- Short Name:
- J/MNRAS/434/956
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the high-angular-resolution catalogue for the Australia Telescope 20GHz (AT20G, Cat. J/MNRAS/402/2403) survey, using the high-angular-resolution 6-km antenna data at the baselines of ~4500m of the Australia Telescope Compact Array. We have used the data to produce the visibility catalogue that separates the compact active galactic nuclei (AGNs) from the extended radio sources at the 0.15arcsec angular scale, corresponding to the linear size scale of 1kpc at redshifts higher than 0.7. We find the radio population at 20GHz to be dominated by compact AGNs constituting 77% of the total sources in the AT20G. We introduce the visibility-spectra diagnostic plot, produced using the AT20G cross-matches with lower frequency radio surveys at 1GHz [the NRAO VLA Sky Survey (NVSS, Cat. VIII/65) and the Sydney University Molonglo Sky Survey (SUMSS, Cat. VIII/81)], that separates the 20GHz population into distinct sub-populations of the compact AGNs, the compact steep-spectrum (CSS) sources, the extended AGN-powered sources and extended flat-spectrum sources. The extended flat-spectrum sources include a local thermal emitting population of high-latitude planetary nebulae and also gravitational lens and binary black hole candidates among the AGNs. We find a smooth transition in properties between the CSS sources and the AGN populations. The visibility catalogue, together with the main AT20G survey, provides an estimate of angular size scales for sources in the AT20G and an estimate of the flux arising from central cores of extended radio sources. The identification of the compact AGNs in the AT20G survey provides high-quality calibrators for high-frequency radio telescope arrays and very large baseline interferometry observations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/2221
- Title:
- ATLAS3D Project. XXXI
- Short Name:
- J/MNRAS/458/2221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a high-resolution, 5GHz, Karl G. Jansky Very Large Array study of the nuclear radio emission in a representative subset of the atlas^3D^ survey of early-type galaxies (ETGs). We find that 51+/-4 per cent of the ETGs in our sample contain nuclear radio emission with luminosities as low as 10^18^W/Hz. Most of the nuclear radio sources have compact (<~25-110pc) morphologies, although ~10 per cent display multicomponent core+jet or extended jet/lobe structures. Based on the radio continuum properties, as well as optical emission line diagnostics and the nuclear X-ray properties, we conclude that the majority of the central 5GHz sources detected in the atlas^3D^ galaxies are associated with the presence of an active galactic nucleus (AGN). However, even at subarcsecond spatial resolution, the nuclear radio emission in some cases appears to arise from low-level nuclear star formation rather than an AGN, particularly when molecular gas and a young central stellar population is present. This is in contrast to popular assumptions in the literature that the presence of a compact, unresolved, nuclear radio continuum source universally signifies the presence of an AGN. Additionally, we examine the relationships between the 5 GHz luminosity and various galaxy properties including the molecular gas mass and - for the first time - the global kinematic state. We discuss implications for the growth, triggering, and fuelling of radio AGNs, as well as AGN-driven feedback in the continued evolution of nearby ETGs.
- ID:
- ivo://CDS.VizieR/J/ApJ/824/29
- Title:
- ATLASGAL clumps with IRAS flux and MALT90 data
- Short Name:
- J/ApJ/824/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a survey of 65 galaxies, Gao & Solomon (2004ApJS..152...63G) found a tight linear relation between the infrared luminosity (L_IR_, a proxy for the star formation rate) and the HCN(1-0) luminosity (L_HCN_). Wu et al. (2005ApJ...635L.173W) found that this relation extends from these galaxies to the much less luminous Galactic molecular high-mass star-forming clumps (~1pc scales), and posited that there exists a characteristic ratio L_IR_/L_HCN_ for high-mass star-forming clumps. The Gao-Solomon relation for galaxies could then be explained as a summation of large numbers of high-mass star-forming clumps, resulting in the same L_IR_/L_HCN_ ratio for galaxies. We test this explanation and other possible origins of the Gao-Solomon relation using high-density tracers (including HCN(1-0), N_2_H^+^(1-0), HCO^+^(1-0), HNC(1-0), HC_3_N(10-9), and C_2_H(1-0)) for ~300 Galactic clumps from the Millimetre Astronomy Legacy Team 90GHz (MALT90) survey. The MALT90 data show that the Gao-Solomon relation in galaxies cannot be satisfactorily explained by the blending of large numbers of high-mass clumps in the telescope beam. Not only do the clumps have a large scatter in the L_IR_/L_HCN_ ratio, but also far too many high-mass clumps are required to account for the Galactic IR and HCN luminosities. We suggest that the scatter in the L_IR_/L_HCN_ ratio converges to the scatter of the Gao-Solomon relation at some size-scale >~1kpc. We suggest that the Gao-Solomon relation could instead result from of a universal large-scale star formation efficiency, initial mass function, core mass function, and clump mass function.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A21
- Title:
- ATLASGAL deuteration of ammonia
- Short Name:
- J/A+A/649/A21
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Deuteration has been used as a tracer of the evolutionary phases of low- and high-mass star formation. The APEX Telescope Large Area Survey (ATLASGAL) provides an important repository for a detailed statistical study of massive star-forming clumps in the inner Galactic disc at different evolutionary phases. We study the amount of deuteration using NH_2_D in a representative sample of high-mass clumps discovered by the ATLASGAL survey covering various evolutionary phases of massive star formation. The deuterium fraction of NH_3_ is derived from the NH_2_D 1_11_-1_01_ortho transition at ~86GHz and NH_2_D 1_11_-1_01_para line at ~110GHz. This is refined for the first time by measuring the NH_2_D excitation temperature directly with the NH_2_D 2_12_-2_02_para transition at ~74GHz. Any variation of NH_3_ deuteration and ortho-to-para ratio with the evolutionary sequence is analysed. Unbiased spectral line surveys at 3mm were conducted towards ATLASGAL clumps between 85 and 93GHz with the Mopra telescope and from 84 to 115GHz using the IRAM 30m telescope. A subsample was followed up in the NH_2_D transition at 74GHz with the IRAM 30m telescope. We determined the deuterium fractionation from the column density ratio of NH_2_D and NH_3_ and measured the NH_2_D excitation temperature for the first time from the simultaneous modelling of the 74 and 110GHz line using MCWeeds. We searched for trends in NH_3_ deuteration with the evolutionary sequence of massive star formation. We derived the column density ratio from the 86 and 110GHz transitions as an estimate of the NH_2_D ortho-to-para ratio. We find a large range of the NH_2_D to NH_3_ column density ratio up to 1.6+/-0.7 indicating a high degree of NH_3_ deuteration in a subsample of the clumps. Our analysis yields a clear difference between NH_3_ and NH_2_D rotational temperatures for a fraction. We therefore advocate observation of the NH_2_D transitions at 74 and 110GHz simultaneously to determine the NH_2_D temperature directly. We determine a median ortho-to-para column density ratio of 3.7+/-1.2. The high detection rate of NH_2_D confirms a high deuteration previously found in massive star-forming clumps. Using the excitation temperature of NH_2_D instead of NH_3_ is needed to avoid an overestimation of deuteration. We measure a higher detection rate of NH_2_D in sources at early evolutionary stages. The deuterium fractionation shows no correlation with evolutionary tracers such as the NH_3_ (1,1) line width, or rotational temperature.