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821. IRAS03301+3057 water masers
ID:
ivo://CDS.VizieR/J/ApJ/628/789
Title:
IRAS03301+3057 water masers
Short Name:
J/ApJ/628/789
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work we present VLA observations of the NH3, CCS, and H2O maser emission at 1cm from the star-forming region B1-IRS (IRAS 03301+3057) with ~5" (=1750AU) of angular resolution. The CCS emission is distributed in three clumps around the central source. These clumps exhibit a velocity gradient from red- to blueshifted velocities toward B1-IRS, probably due to an interaction with the outflow from an embedded protostar.
822. IRC+10216 carbon chains mapped with ALMA
ID:
ivo://CDS.VizieR/J/A+A/601/A4
Title:
IRC+10216 carbon chains mapped with ALMA
Short Name:
J/A+A/601/A4
Date:
21 Oct 2021
Publisher:
CDS
Description:
Linear carbon chains are common in various types of astronomical molecular sources. Possible formation mechanisms involve both bottom-up and top-down routes. We have carried out a combined observational and modeling study of the formation of carbon chains in the C-star envelope IRC +10216, where the polymerization of acetylene and hydrogen cyanide induced by ultraviolet photons can drive the formation of linear carbon chains of increasing length. We have used ALMA to map the emission of 3 mm rotational lines of the hydrocarbon radicals C_2_H, C_4_H, and C_6_H, and the CN-containing species CN, C_3_N, HC_3_N, and HC_5_N with an angular resolution of 1". The spatial distribution of all these species is a hollow 5-10" wide spherical shell located at a radius of 10-20" from the star, with no appreciable emission close to the star. Our observations resolve the broad shell of carbon chains into thinner subshells that are 1-2" wide and not fully concentric, indicating that the mass-loss process has been discontinuous and not fully isotropic. The radial distributions of the species mapped reveal subtle differences: while the hydrocarbon radicals have very similar radial distributions, the CN-containing species show more diverse distributions, with HC_3_N appearing earlier in the expansion and the radical CN extending later than the rest of the species. The observed morphology can be rationalized by a chemical model in which the growth of polyynes is mainly produced by rapid gas-phase chemical reactions of C_2_H and C_4_H radicals with unsaturated hydrocarbons, while cyanopolyynes are mainly formed from polyynes in gas-phase reactions with CN and C_3_N radicals.
823. IRDC 19175-4 and IRDC 19175-5 turbulence maps
ID:
ivo://CDS.VizieR/J/A+A/503/859
Title:
IRDC 19175-4 and IRDC 19175-5 turbulence maps
Short Name:
J/A+A/503/859
Date:
21 Oct 2021
Publisher:
CDS
Description:
The aims is to characterizing the gas and dust properties prior to and in the neighborhood of active intermediate- to high-mass star formation. Two Infrared Dark Clouds (IRDCs), IRDC 19175-4 and IRDC 19175-5, that are located in the vicinity of the luminous massive star-forming region IRAS 19175+1357, but that remain absorption features up to 70um wavelength, were observed with the Plateau de Bure Interferometer in the 3.23mm dust continuum as well as the N2H^+^(1-0) and ^13^CS(2-1) line emission.
824. IR-radio luminosities & surface densities of galaxies
ID:
ivo://CDS.VizieR/J/ApJ/805/31
Title:
IR-radio luminosities & surface densities of galaxies
Short Name:
J/ApJ/805/31
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the global star formation law --the relation between gas and star formation (SF) rates-- in a sample of 181 local galaxies with infrared (IR) luminosities spanning almost five orders of magnitude (10^7.8^-10^12.3^L_{sun}_), which includes 115 normal spiral galaxies and 66 (ultra)luminous IR galaxies ((U)LIRGs, L_IR_>>10^11^L_{sun}_). We derive their atomic, molecular gas, and dense molecular gas masses using newly available HI, CO, and HCN data from the literature, and SF rates are determined both from total IR (8-1000um) and 1.4GHz radio continuum (RC) luminosities. In order to derive the disk-averaged surface densities of gas and SF rates, we have taken a novel approach and used high-resolution RC observations to measure the radio sizes for all 181 galaxies. In our sample, we find that the surface density of dense molecular gas (as traced by HCN) has the tightest correlation with that of SF rates ({Sigma}_SFR_), and is linear in log-log space (power-law slope of N=1.01+/-0.02) across the full galaxy sample. The correlation between surface densities of molecular gas ({Sigma}_H_2__, traced by CO) and {Sigma}_SFR_ is sensitive to the adopted value of the CO-to-H_2_ conversion factor ({alpha}_CO_) used to infer molecular gas masses from CO luminosities. For a fixed Galactic value of {alpha}_CO_, a power law index of 1.14+/-0.02 is found. If instead we adopt values for {alpha}_CO_ of 4.6 and 0.8 for disk galaxies and (U)LIRGs, respectively, we find the two galaxy populations separate into two distinct {Sigma}_SFR_ versus {Sigma}_H_2__ relations. Finally, applying a continuously varying {alpha}_CO_ to our sample, we recover a single {Sigma}_SFR_-{Sigma}_H_2__ relation with slope of 1.60+/-0.03. The {Sigma}_SFR_ is a steeper function of total gas {Sigma}_gas_ (molecular gas with atomic gas) than that of molecular gas {Sigma}_H_2__, and are tighter among low-luminosity galaxies. We find no correlation between global surface densities of SFRs and atomic gas (HI).
825. ISO ELAIS 20cm VLA survey regions
ID:
ivo://CDS.VizieR/J/MNRAS/302/222
Title:
ISO ELAIS 20cm VLA survey regions
Short Name:
J/MNRAS/302/222
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the Very Large Array (VLA) in C configuration to carry out a sensitive 20-cm radio survey of regions of the sky that have been surveyed in the far-infrared (FIR) over the wavelength range 5-200{mu}m with ISO (Infrared Space Observatory) as part of the European Large-Area ISO Survey (ELAIS). As usual in surveys based on a relatively small number of overlapping VLA pointings, the flux limit varies over the area surveyed: from a 5{sigma} limit of 0.135mJy over an area of 0.12deg^2^ to 1.15mJy or better over the whole region covered of 4.22deg^2^. In this paper we present the complete radio catalogue of 867 sources, 428 of which form a complete sample in the flux range 0.2-1.0mJy. These regions of the sky have previously been surveyed to shallower flux limits at 20cm with the VLA as part of the VLA D configuration NVSS (full width at half-maximum, FWHM=45arcsec) and VLA B configuration FIRST (FWHM=5arcsec) surveys. Our whole survey has a nominal 5{sigma} flux limit a factor of 2 below that of the NVSS; 3.4deg^2^ of the survey reaches the nominal flux limit of the FIRST survey and 1.5deg^2^ reaches 0.25mJy, a factor of 4 below the nominal FIRST survey limit. In addition, our survey is at a resolution intermediate between the two surveys and thus is well suited for a comparison of the reliability and resolution-dependent surface brightness effects that affect interferometric radio surveys. We have carried out a detailed comparison of our own survey and these two independent surveys in order to assess the reliability and completeness of each. Considering the whole sample, we found that to the 5{sigma} nominal limits of 2.3 and 1.0mJy, respectively, the NVSS and FIRST surveys have a completeness of 96^+2^_-3_ and 89^+2^_-3_ per cent and a reliability of 99^+1^_-2_ and 94^+2^_-2_ per cent.
826. ISO ELAIS 1.4GHz survey
ID:
ivo://CDS.VizieR/J/MNRAS/305/297
Title:
ISO ELAIS 1.4GHz survey
Short Name:
J/MNRAS/305/297
Date:
21 Oct 2021
Publisher:
CDS
Description:
A deep survey of the European Large-Area ISO Survey (ELAIS) field in the southern celestial hemisphere (hereinafter S1) has been carried out with the Australia Telescope Compact Array (ATCA) at 1.4GHz. The S1 region, covering about 4deg^2^, has also been surveyed in the mid- and far-infrared (5-200mm) with the Infrared Space Observatory (ISO). The radio survey provides uniform coverage of the entire S1 region, with a sensitivity (5{sigma}) of 0.4mJy over the whole area and 0.2mJy in the centre. To this sensitivity, virtually all the radio counterparts of the far-infrared extragalactic ISO sources should be detected. This paper presents a radio sample -- complete at the 5{sigma} level -- consisting of 581 sources detected at 1.4GHz. Of these radio sources, 349 have peak flux density in the range 0.2-1mJy, forming a new homogeneous sample of sub-mJy radio sources. Due to its size, depth and multiwaveband coverage, the sample will allow us to study in greater detail the sub-mJy radio source population.
827. ISOSS22478 and ISOSS23053 images
ID:
ivo://CDS.VizieR/J/A+A/649/A113
Title:
ISOSS22478 and ISOSS23053 images
Short Name:
J/A+A/649/A113
Date:
22 Feb 2022
Publisher:
CDS
Description:
The formation of high-mass star-forming regions from their parental gas cloud and the subsequent fragmentation processes lie at the heart of star formation research. We aim to study the dynamical and fragmentation properties at very early evolutionary stages of high-mass star formation. Employing the NOrthern Extended Millimeter Array (NOEMA) and the IRAM 30m telescope, we observe two young high-mass star-forming regions, ISOSS22478 and ISOSS23053, in the 1.3mm continuum and spectral line emission at high angular resolution (~0.8''). Resolving altogether 29 cores that are largely located along filament-like structures, we find that these cores follow a mass-size relation of approximately M~r^3^, corresponding to a constant mean density of roughly 10^6cm^-3^. The correlation of the core masses with their nearest neighbor separations is consistent with thermal Jeans fragmentation. Although the kinematics of the two regions appear very different at first sight -- multiple velocity components along filaments in ISOSS22478 versus a steep velocity gradient of more than 50km/s/pc in ISOSS23053 -- the findings can all be explained in the framework of a dynamical cloud collapse scenario. While our data are consistent with a dynamical cloud collapse scenario and subsequent thermal Jeans fragmentation, the importance of additional environmental properties -- e.g., the magnetization of the gas or external shocks triggering converging gas flows -- is still less well constrained and requires future investigation.
828. J1717-3342 and J1744-3116 CO spectra
ID:
ivo://CDS.VizieR/J/A+A/648/A38
Title:
J1717-3342 and J1744-3116 CO spectra
Short Name:
J/A+A/648/A38
Date:
21 Oct 2021
Publisher:
CDS
Description:
The chemistry of the diffuse interstellar medium is driven by the combined influences of cosmic rays, ultraviolet (UV) radiation, and turbulence. Previously detected at the outer edges of photodissociation regions (PDRs) and formed from the reaction of C^+^ and OH, CO^+^ is the main chemical precursor of HCO^+^ and CO in a thermal, cosmic-ray, and UV-driven chemistry. Our aim was to test whether the thermal cosmic-ray and UV-driven chemistry is producing CO in diffuse interstellar molecular gas through the intermediate formation of CO^+^ We searched for CO^+^ absorption with the Atacama Large Millimeter Array (ALMA) toward two quasars with known Galactic foreground absorption from diffuse interstellar gas, J1717-3342 and J1744-3116, targeting the two strongest hyperfine components of the J=2-1 transition near 236GHz. We could not detect CO^+^ but obtained sensitive upper limits toward both targets. The derived upper limits on the CO^+^ column densities represent about 4% of the HCO^+^ column densities. The corresponding upper limit on the CO^+^ abundance relative to H_2_ is <1.2x10^-10^. The non-detection of CO^+^ confirms that HCO^+^ is mainly produced in the reaction between oxygen and carbon hydrides, CH2^+^ or CH3^+^, induced by suprathermal processes, while CO^+^ and HOC^+^ result from reactions of C^+^ with OH and H_2_O. The densities r equired to form CO molecules at low extinction are consistent with this scheme.
829. JCMT/SCUBA2 objects in COSMOS and UDS fields
ID:
ivo://CDS.VizieR/J/MNRAS/469/492
Title:
JCMT/SCUBA2 objects in COSMOS and UDS fields
Short Name:
J/MNRAS/469/492
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses (M*)] of bright (S_850_>=4mJy) submm galaxies in the ~=2deg^2^ COSMOS and UDS fields selected with SCUBA-2/JCMT. We complete the galaxy identification process for all (~=2000) S/N>=3.5 850-{mu}m sources, but focus our scientific analysis on a high-quality subsample of 651 S/N>=4 sources with complete multiwavelength coverage including 1.1-mm imaging. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up of 29 sources in our sample. Considering >4mJy ALMA sources, our identification method has a completeness of ~=86 per cent with a reliability of ~=92 per cent, and only ~=15-20 per cent of sources are significantly affected by multiplicity (when a secondary component contributes >1/3 of the primary source flux). The impact of source blending on the 850-{mu}m source counts as determined with SCUBA-2 is modest; scaling the single-dish fluxes by ~=0.9 reproduces the ALMA source counts. For our final SCUBA-2 sample, we find median z=2.40^+0.10^_-0.04_, SFR=287+/-6M_{sun}_/yr and log(M*/M_{sun)_=11.12+/-0.02 (the latter for 349/651 sources with optical identifications). These properties clearly locate bright submm galaxies on the high-mass end of the 'main sequence' of star-forming galaxies out to z~= 6, suggesting that major mergers are not a dominant driver of the high-redshift submm-selected population. Their number densities are also consistent with the evolving galaxy stellar mass function. Hence, the submm galaxy population is as expected, albeit reproducing the evolution of the main sequence of star-forming galaxies remains a challenge for theoretical models/simulations.
830. Jellyfish galaxy JO201 JVLA datacube
ID:
ivo://CDS.VizieR/J/A+A/640/A22
Title:
Jellyfish galaxy JO201 JVLA datacube
Short Name:
J/A+A/640/A22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present HI observations of the jellyfish galaxy, JO201, a massive galaxy falling along the line-of-sight towards the centre of a rich cluster, A85 at a high velocity. Its H{alpha} emission shows a ~40kpc tail confined closely to its stellar disc and a ~100kpc tail extending further out. We find HI emission coinciding only with the shorter clumpy H{alpha} tail while no HI emission is detected along the ~100kpc Ha tail. In total, we measure an HI mass of M_HI_=1.65x10^+9^M_{sun}_, which is about 60% lower than expected based on its stellar mass and stellar surface density. We compared JO201 to another jellyfish in the GASP sample, JO206, and find that they are similarly HI-deficient. The global star formation rate (SFR) analysis of JO201 suggests that its observed SFR would be expected if it had 10x its current HI mass. The disc is the main contributor of the high star formation efficiency at a given HI gas density for both galaxies, but their tails also show higher star formation efficiencies compared to the outer regions of field galaxies. Generally, we find that JO201 and JO206 are similar based on their HI content, stellar mass and star formation rate. This finding is unexpected considering their different environments. A toy model comparing the ram pressure of the ICM versus the restoring forces of these galaxies suggests that the ram pressure strength exerted on them could be comparable if we consider their 3D orbital velocities and radial distances relative to the clusters.