- ID:
- ivo://CDS.VizieR/J/A+A/549/A45
- Title:
- ATLASGAL Compact Source Catalog: 330<l<21
- Short Name:
- J/A+A/549/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ATLASGAL compact source catalog is based on the ATLASGAL survey. This survey was made using the LABOCA bolometer array at APEX, at 870-microns covering the Galactic Plane between 330 degrees and 21-degrees in Galactic longitude and -1.5 to +1.5-degrees in Galactic Latitude. This catalog was created using SEXTRACTOR and contains 6639 sources, with a 99% completeness for sources with peak flux above 6{sigma}.
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- ID:
- ivo://CDS.VizieR/J/A+A/591/A5
- Title:
- ATLASGAL dense filamentary structures
- Short Name:
- J/A+A/591/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the properties of filamentary structures from the ATLASGAL survey. We use the DisPerSE algorithm to identify spatially coherent structures located across the inner-Galaxy (300<l<60 and |b|<1.5). We have determined distances, masses and physical sizes for 241 of the filamentary structures. We find a median distance of 3.8kpc, a mean mass of a few 10^3^M_{sun}_, a mean length of ~6pc and a mass-to-length ratio of (M/L)~200-2000M_sun/pc. We also find that these filamentary structures are tightly correlated with the spiral arms in longitude and velocity, and that their semi-major axis is preferentially aligned parallel to the Galactic mid-plane and therefore with the direction of large-scale Galactic magnetic field. We find many examples where the dense filaments identified in ATLASGAL are associated with larger scale filamentary structures (~100pc), and argue that this is likely to be common, and as such these may indicate a connection between large-scale Galactic dynamics and star formation. We have produced a large and Galaxy-wide catalogue of dense filamentary structures that are representative of a particular size and mass range not previously well studied in the literature. Analyses of the properties and distribution of these filaments reveals that they are correlated with the spiral arms and make a significant contribution to star formation in the Galaxy. Massive star formation is ongoing within ~20% of the filaments and is strongly correlated with the filaments with the largest mass-to- length ratios. The luminosity of the embedded sources has a similar distribution to the Galactic-wide samples of young massive stars and can therefore be considered to be representative.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A75
- Title:
- ATLASGAL: dust condensations in Galactic plane
- Short Name:
- J/A+A/565/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation processes and the evolutionary stages of high-mass stars are poorly understood compared to low-mass stars. Large-scale surveys are needed to provide an unbiased census of high column density sites which can potentially host precursors to high-mass stars. The ATLASGAL survey covers 420 sq. degree of the Galactic plane, between -80{deg}<l<+60{deg} at 870um. Here we identify the population of embedded sources throughout the inner Galaxy. With this catalog we first investigate the general statistical properties of dust condensations in terms of their observed parameters, such as flux density and angular size. Then using mid-IR surveys we aim to investigate their star-formation activity and the Galactic distribution of star-forming and quiescent clumps. Our ultimate goal is to determine the statistical properties of quiescent and star-forming clumps within the Galaxy and to constrain the star-formation processes. We optimized the source extraction method, referred to as MRE-GCL, for the ATLASGAL maps in order to generate a catalog of compact sources. This technique is based on a multi-scale filtering to remove extended emission from clouds to better determine the parameters corresponding to the embedded compact sources. In a second step we extract the sources by fitting 2D Gaussians with the Gaussclumps algorithm.
- ID:
- ivo://CDS.VizieR/J/A+A/579/A91
- Title:
- ATLASGAL inner Galaxy massive cold dust clumps
- Short Name:
- J/A+A/579/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of high mass stars and clusters occurs in giant molecular clouds. Objects in evolved stages of massive star formation such as protostars, hot molecular cores, and ultracompact HII regions have been studied in more detail than earlier, colder objects. Further progress thus requires the analysis of the time before massive protostellar objects can be probed by their infrared emission. With this in mind, the APEX Telescope Large Area Survey of the whole inner Galactic plane at 870{mu}m (ATLASGAL) has been carried out to provide a global view of cold dust and star formation at submillimetre wavelengths. We derive kinematic distances to a large sample of massive cold dust clumps from their measured line velocities. We estimate masses and sizes of ATLASGAL sources, for which the kinematic distance ambiguity is resolved. The ATLASGAL sample is divided into groups of sources, which are located close together, mostly within a radius of 2pc, and have velocities in a similar range with a median velocity dispersion of ~1km/s. We use NH_3_, N_2_H^+^, and CS velocities to calculate near and far kinematic distances to those groups. We obtain 296 groups of ATLASGAL sources in the first quadrant and 393 groups in the fourth quadrant, which are coherent in space and velocity. We analyse HI self-absorption and HI absorption to resolve the kinematic distance ambiguity to 689 complexes of submm clumps. They are associated with ^12^CO emission probing large-scale structure and ^13^CO (1-0) line as well as the 870{mu}m dust continuum on a smaller scale. We obtain a scale height of ~28+/-2pc and displacement below the Galactic midplane of ~-7+/-1pc. Within distances from 2 to 18kpc ATLASGAL clumps have a broad range of gas masses with a median of 1050M_{sun}_ as well as a wide distribution of radii with a median of 0.4pc. Their distribution in galactocentric radii is correlated with spiral arms. Using a statistically significant ATLASGAL sample we derive a power-law exponent of -2.2+/-0.1 of the clump mass function. This is consistent with the slope derived for clusters and with that of the stellar initial mass function. Examining the power-law index for different galactocentric distances and various source samples shows that it is independent of environment and evolutionary phase. Fitting the mass-size relationship by a power law gives a slope of 1.76+/-0.01 for cold sources such as IRDCs and warm clumps associated with HII regions.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A60
- Title:
- ATLASGAL: Massive cluster progenitors sample
- Short Name:
- J/A+A/601/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The progenitors of high-mass stars and clusters are still challenging to recognise. Only unbiased surveys, sensitive to compact regions of high dust column density, can unambiguously reveal such a small population of particularly massive and cold clumps. Here we use the ATLASGAL survey to identify a sample of candidate progenitors of massive clusters in the inner Galaxy. We characterise a flux limited sample of compact sources selected from the ATLASGAL survey. Sensitive mid-infrared data at 21-24um from the WISE and MIPSGAL surveys were explored to search for embedded objects, and complementary spectroscopic data were used to investigate their stability and their star formation activity. We identify an unbiased sample of infrared-quiet massive clumps in the Galaxy that potentially represent the earliest stages of massive cluster formation. An important fraction of this sample consists of sources that have not been studied in detail before. We first find that clumps hosting more evolved embedded objects and infrared-quiet clumps exhibit similar physical properties in terms of mass and size, suggesting that the sources are not only capable of forming high-mass stars, but likely also follow a single evolutionary track leading to the formation of massive clusters. The majority of the clumps are likely not in virial-equilibrium, suggesting collapse on the clump scale.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A160
- Title:
- ATLASGAL-selected massive clumps. Chemistry of PDR
- Short Name:
- J/A+A/644/A160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study ten molecular transitions obtained from an unbiased 3mm molecular line survey using the IRAM 30m telescope toward 409 compact dust clumps identified by the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) to better understand the photodissociation regions (PDRs) associated with these clumps. The main goal of this study is to investigate whether the abundances of the selected molecules show any variations resulting from the PDR chemistry in different clump environments. We selected HCO, HOC^+^, C_2_H, c-C_3_H_2_, CN, H^13^CN, HC^15^N, and HN^13^C as PDR tracers, and H^13^CO^+^ and C^18^O as dense gas tracers. By using estimated optical depths of C_2_H and H^13^CN and assuming optically thin emission for other molecular transitions, we derived the column densities of those molecules and their abundances. To assess the influence of the presence and strength of ultra- violet radiation, we compare abundances of three groups of the clumps: HII regions, infrared bright non-HII regions, and infrared dark non-HII regions. We detected C^18^O, H^13^CO^+^, C_2_H, c-C_3_H_2_, CN, and HN^13^C toward most of the observed dust clumps (detection rate >94%), and H^13^CN is also detected with a detection rate of 75%. On the other hand, HCO and HC^15^N show detection rates of 32% and 39%, respectively, toward the clumps, which are mostly associated with HII region sources: Detection rates of HCO and HC^15^N toward the HII regions are 66% and 79%. We find that the abundances of HCO, CN, C_2_H, and c-C_3_H_2_ decrease as the H_2_ column density increases, indicating high visual extinction, while those of high-density tracers (i.e., H^13^CO^+^ and HC^15^N) are constant. In addition, N(HCO)/N(H^13^CO^+^) ratios significantly decrease as H_2_ column density increases, and, in particular, 82 clumps have X(HCO)>=10^-10^ and N(HCO)/N(H^13^CO^+^)>~1, which are indications of far-ultraviolet (FUV) chemistry. This suggests the observed HCO abundances are likely associated with FUV radiation illuminating the PDRs. We also find that high N(c-C_3_H_2_)/N(C_2_H) ratios found for HII regions that have high HCO abundances (>~10^-10^) are associated with more evolved clumps with high L_bol_/M_clump_. This trend might be associated with gain-surface processes, which determine the initial abundances of these molecules, and time-dependent effects in the clumps corresponding to the envelopes around dense PDRs and HII regions. In addition, some fraction of the measured abundances of the small hydrocarbons of the HII sources may be the result of the photodissociation of PAH molecules.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/2555
- Title:
- ATLAS 1.4GHz Data Release 2
- Short Name:
- J/MNRAS/441/2555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first of two papers describing the second data release (DR2) of the Australia Telescope Large Area Survey at 1.4GHz, which comprises deep wide-field observations in total intensity, linear polarization, and circular polarization over the Chandra Deep Field-South and European Large Area Infrared Space Observatory Survey-South 1 regions. DR2 improves upon the first data release by maintaining consistent data reductions across the two regions, including polarization analysis, and including differential number counts in total intensity and linear polarization. Typical DR2 sensitivities across the mosaicked multipointing images are 30{mu}Jy/beam at approximately 12"x6" resolution over a combined area of 6.4deg^2^. In this paper we present detailed descriptions of our data reduction and analysis procedures, including corrections for instrumental effects such as positional variations in image sensitivity, bandwidth smearing with a non-circular beam, and polarization leakage, and application of the BLOBCAT source extractor. We present the DR2 images and catalogues of components (discrete regions of radio emission) and sources (groups of physically associated radio components). We describe new analytic methods to account for resolution bias and Eddington bias when constructing differential number counts of radio components.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/4020
- Title:
- ATLAS 1.4GHz Data Release 3
- Short Name:
- J/MNRAS/453/4020
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third data release from the Australia Telescope Large Area Survey. These data combine the observations at 1.4GHz before and after upgrades to the Australia Telescope Compact Array reaching a sensitivity of 14{mu}Jy/beam in 3.6 deg^2^ over the Chandra Deep Field South (CDFS) and of 17{mu}Jy/beam in 2.7 deg^2^ over the European Large Area ISO Survey South 1 (ELAIS-S1). We used a variety of array configurations to maximize the uv coverage resulting in a resolution of 16 by 7-arcsec in CDFS and of 12 by 8-arcsec in ELAIS-S1. After correcting for peak bias and bandwidth smearing, we find a total of 3034 radio source components above 5{sigma} in CDFS, of which 514 (17 per cent) are considered to be extended. The number of components detected above 5{sigma} in ELAIS-S1 is 2084, of which 392 (19 per cent) are classified as extended. The catalogues include reliable spectral indices ({Delta}{alpha}<0.2) between 1.40 and 1.71GHz for ~350 of the brightest components.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A38
- Title:
- ATLAS 2.3GHz observations of ELAIS-S1 and CDF-S
- Short Name:
- J/A+A/544/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Australia Telescope Large Area Survey (ATLAS) aims to image a 7deg^2^ region centred on the European Large Area ISO Survey - South 1 (ELAIS-S1) field and the Chandra Deep Field South (CDF-S) at 1.4GHz with high sensitivity (up to {sigma}~10uJy) to study the evolution of star-forming galaxies (SFGs) and Active Galactic Nuclei (AGN) over a wide range of cosmic time. We present here ancillary radio observations at a frequency of 2.3GHz obtained with the Australia Telescope Compact Array (ATCA). The main goal of this is to study the radio spectra of an unprecedented large sample of sources (~2000 observed, ~600 detected in both frequencies).
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/2342
- Title:
- ATLAS 5.5GHz survey of Chandra Deep Field South
- Short Name:
- J/MNRAS/426/2342
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Star-forming galaxies are thought to dominate the sub-mJy radio population, but recent work has shown that low-luminosity active galactic nuclei (AGNs) can still make a significant contribution to the faint radio source population. Spectral indices are an important tool for understanding the emission mechanism of the faint radio sources. We have observed the extended Chandra Deep Field South at 5.5GHz using a mosaic of 42 pointings with the Australia Telescope Compact Array. Our image reaches an almost uniform sensitivity of ~12Jy rms over 0.25deg^2^ with a restoring beam of 4.9"x2.0", making ATLAS 5.5GHz survey one of the deepest 6cm surveys to date. We present the 5.5GHz catalogue and source counts from this field. We take advantage of the large amount of ancillary data in this field to study the 1.4 to 5.5GHz spectral indices of the sub-mJy population.