- ID:
- ivo://CDS.VizieR/J/A+A/614/A42
- Title:
- PKS B1718-649 ALMA observations
- Short Name:
- J/A+A/614/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ALMA observations of the ^12^CO (2-1) line of the newly born (t_radio_~10^2^years) active galactic nucleus (AGN), PKS B1718-649. These observations reveal that the carbon monoxide in the innermost 15 kpc of the galaxy is distributed in a complex warped disk. In the outer parts of this disk, the CO gas follows the rotation of the dust lane and of the stellar body of the galaxy hosting the radio source. In the innermost kiloparsec, the gas abruptly changes orientation and forms a circumnuclear disk (r<~700pc) with its major axis perpendicular to that of the outer disk. Against the compact radio emission of PKS B1718-649 (r~2pc), we detect an absorption line at red-shifted velocities with respect to the systemic velocity ({Delta}v=+365+/-22km/s). This absorbing CO gas could trace molecular clouds falling onto the central super-massive black hole. A comparison with the near-infra red H_2_ 1-0 S(1) observations shows that the clouds must be close to the black hole (r<~75pc). The physical conditions of these clouds are different from the gas at larger radii, and are in good agreement with the predictions for the conditions of the gas when cold chaotic accretion triggers an active galactic nucleus. These observations on the centre of PKS B1718-649 provide one of the best indications that a population of cold clouds is falling towards a radio AGN, likely fuelling its activity.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/369/449
- Title:
- PKS 0405-385 flux-density monitoring
- Short Name:
- J/MNRAS/369/449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The quasar PKS 0405-385 is one of three radio sources (the other two are PKS 1257-326 and J1819+385) which exhibit unusually strong and rapid interstellar scintillations at GHz frequencies. Such a behaviour suggests a nearby (<30pc away) scattering screen along the line of sight to these radio sources. While quasars PKS 1257-326 and J1819+385 scintillate continuously over several years of monitoring, PKS 0405-385 shows episodes of strong scintillations which last only a few months. Here, I present the results of flux-density monitoring of PKS 0405-385 over 6yr at four Stokes parameters and four frequencies. Two explanations of the episodic behaviour of interstellar scintillation in this source are discussed; morphological evolution of the source and changes in the properties of the interstellar medium along the line of sight.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A7
- Title:
- PKS1830-211 HDO, ND and NH_2_D spectra
- Short Name:
- J/A+A/637/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deuterium and lithium are light elements of high cosmological and astrophysical importance. In this work we report the first detection of deuterated molecules and a search for lithium hydride, ^7^LiH, at redshift z=0.89 in the spiral galaxy intercepting the line of sight to the quasar PKS 1830-211. We used ALMA to observe several submillimeter lines of ND, NH_2_D, and HDO, and their related isotopomers NH_2_, NH_3_, and H^18^_2_O, in absorption against the southwest image of the quasar, allowing us to derive XD/XH abundance ratios. The absorption spectra mainly consist of two distinct narrow velocity components for which we find remarkable differences. One velocity component shows XD/XH abundances that is about 10 times larger than the primordial elemental D/H ratio, and no variability of the absorption profile during the time span of our observations. In contrast, the other component shows a stronger deuterium fractionation. Compared to the first component, this second component has XD/XH abundances that are 100 times larger than the primordial D/H ratio, a deepening of the absorption by a factor of two within a few months, and a rich chemical composition, with relative enhancements of N_2_H^+^, CH_3_OH, SO_2_ and complex organic molecules. We therefore speculate that this component is associated with the analog of a Galactic dark cloud, while the first component is likely more diffuse. Our search for the ^7^LiH (1-0) line was unsuccessful and we derive an upper limit ^7^LiH/H_2_=4x10^-13^ (3{sigma}) in the z=0.89 absorber toward PKS 1830.211. Besides, with ALMA archival data, we could not confirm the previous tentative detections of this line in the z=0.68 absorber toward B0218+357; we derive an upper limit ^7^LiH/H_2_=5x10^-11^ (3{sigma}), although this is less constraining than our limit toward PKS 1830.211. We conclude that, as in the Milky Way, only a tiny fraction of lithium nuclei are possibly bound in LiH in these absorbers at intermediate redshift.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/43
- Title:
- Planck cold clumps and cores in the 2nd quadrant
- Short Name:
- J/ApJS/224/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ninety-six Planck cold dust clumps in the second quadrant were mapped with ^12^CO(1-0), ^13^CO(1-0), and C^18^O(1-0) lines at the 13.7m telescope of Purple Mountain Observatory. ^12^CO(1-0) and ^13^CO(1-0) emissions were detected for all 96 clumps, while C^18^O(1-0) emissions were detected in 81 of them. Fifteen clumps have more than one velocity component. In the 115 mapped velocity components, 225 cores were obtained. We found that 23.1% of the cores have non-Gaussian profiles. We acquired the V_lsr_, FWHM, and T_A_ of the lines. Distances, T_ex_, velocity dispersions, N_H_2__, and masses were also derived. Generally, turbulence may dominant the cores because {sigma}_NT_/{sigma}_Therm_>1 in almost all of the cores and Larson's relationship is not apparent in our massive cores. Virial parameters are adopted to test the gravitational stability of cores and 51% of the cores are likely collapsing. The core mass function of the cores in the range 0-1kpc suggests a low core-to-star conversional efficiency (0.62%). Only 14 of 225 cores (6.2%) have associated stellar objects at their centers, while the others are starless. The morphologies of clumps are mainly filamentary structures. Seven clumps may be located on an extension of the new spiral arm in the second quadrant while three are on the known outer arm.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/37
- Title:
- Planck cold clumps in ^12^CO, ^13^CO and C^18^O
- Short Name:
- J/ApJS/209/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A mapping study of 71 Planck cold clumps was made with ^12^CO(1-0), ^13^CO(1-0), and C^18^O(1-0) lines at the 13.7m telescope of Purple Mountain Observatory. For all the clumps, ^12^CO(1-0) and ^13^CO(1-0) emissions were detected, while for 55 of them, C^18^O(1-0) emissions were detected. Of the 71 Clumps, 34 are in the Taurus Complex, 24 in the California Complex, and 13 are in the Perseus Complex. In the 76 velocity components, 38 cores are found in 27 clumps; 19 of these cores are in the Taurus Complex, 16 in the California Complex, and 3 in the Perseus Complex. We acquired V_lsr_, T_A_ and FWHM of lines. Physical parameters including T_ex_, N_H2_, {sigma}_Therm_, {sigma}_NT_, and {sigma}_3D_were calculated. Generally, the cores are of T_ex_=2-16K, N_H2_/cm2, and {sigma}_3D_=0.2-1.0km/s. In the Taurus Complex, the cores are less dense on average and have smaller {sigma}_Therm_than the cores in the Perseus and California Complexes. Two of the three cores in the Perseus Complex are revealed to have larger T_ex_, N_H2_, and {sigma}_3D_ than the mean values in the other two regions. Most of the cores have {sigma}_NT_larger than {sigma}_Therm_, suggesting a dominance of turbulence in our cores. The majority of the cores have M_vir_/M_LTE_{Gt} 1, which indicates these cores are not bound and will disperse. By comparing our results with the dust properties revealed by the Planck Early Release Cold Cores Catalog, we investigated the coupling of gas and dust components. We found that most of the cores have dust temperatures higher than their gas temperatures. The stellar objects associated with our sources were checked and 90% of the cores were found to be starless.
- ID:
- ivo://CDS.VizieR/J/ApJS/254/14
- Title:
- Planck Cold Clumps in the lambda Orionis complex. III.
- Short Name:
- J/ApJS/254/14
- Date:
- 17 Jan 2022 00:15:36
- Publisher:
- CDS
- Description:
- Massive stars have a strong impact on their local environments. However, how stellar feedback regulates star formation is still under debate. In this context, we studied the chemical properties of 80 dense cores in the Orion molecular cloud complex composed of the Orion A (39 cores), B (26 cores), and {lambda} Orionis (15 cores) clouds using multiple molecular line data taken with the Korean Very Long Baseline Interferometry Network 21m telescopes. The {lambda} Orionis cloud has an HII bubble surrounding the O-type star {lambda} Ori, and hence it is exposed to the ultraviolet (UV) radiation field of the massive star. The abundances of C_2_H and HCN, which are sensitive to UV radiation, appear to be higher in the cores in the {lambda} Orionis cloud than in those in the Orion A and B clouds, while the HDCO to H_2_CO abundance ratios show the opposite trend, indicating warmer conditions in the {lambda} Orionis cloud. The detection rates of dense gas tracers such as the N_2_H^+^, HCO^+^, and H^13^CO^+^ lines are also lower in the {lambda} Orionis cloud. These chemical properties imply that the cores in the {lambda} Orionis cloud are heated by UV photons from {lambda} Ori. Furthermore, the cores in the {lambda} Orionis cloud do not show any statistically significant excess in the infall signature of HCO^+^ (1-0), unlike those in the Orion A and B clouds. Our results support the idea that feedback from massive stars impacts star formation in a negative way by heating and evaporating dense materials, as in the {lambda} Orionis cloud.
- ID:
- ivo://CDS.VizieR/J/ApJS/202/4
- Title:
- Planck cold clumps survey in the Orion complex
- Short Name:
- J/ApJS/202/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A mapping survey of 51 Planck cold clumps projected on the Orion complex was performed with J=1-0 lines of ^12^CO and ^13^CO with the 13.7m telescope at the Purple Mountain Observatory. The mean column densities of the Planck gas clumps range from 0.5 to 9.5x10^21^cm^-2^, with an average value of (2.9+/-1.9)x10^21^cm^-2^. The mean excitation temperatures of these clumps range from 7.4 to 21.1K, with an average value of 12.1+/-3.0K and the average three-dimensional velocity dispersion {sigma}_3D_ in these molecular clumps is 0.66+/-0.24km/s. The H2 column density of the molecular clumps calculated from molecular lines correlates with the aperture flux at 857GHz of the dust emission. By analyzing the distributions of the physical parameters, we suggest that turbulent flows can shape the clump structure and dominate their density distribution on large scales, but not function on small scales due to local fluctuations. Eighty-two dense cores are identified in the molecular clumps. The dense cores have an average radius and local thermal equilibrium (LTE) mass of 0.34+/-0.14pc and 38^+5^_-30_M_{sun}_, respectively. The structures of low column density cores are more affected by turbulence, while the structures of high column density cores are more affected by other factors, especially by gravity.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/76
- Title:
- Planck cold dust clumps CO survey
- Short Name:
- J/ApJ/756/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey toward 674 Planck cold clumps of the Early Cold Core Catalogue (ECC) in the J=1-0 transitions of ^12^CO, ^13^CO, and C^18^O has been carried out using the Purple Mountain Observatory 13.7m telescope. Six hundred seventy-three clumps were detected with ^12^CO and ^13^CO emission, and 68% of the sample has C^18^O emission. Additional velocity components were also identified. A close consistency of the three line peak velocities was revealed for the first time. Kinematic distances are given for all the velocity components, and half of the clumps are located within 0.5 and 1.5kpc. Excitation temperatures range from 4 to 27K, slightly larger than those of T_d_. Line width analysis shows that the majority of ECC clumps are low-mass clumps. Ten clumps were mapped. Twelve velocity components and 22 cores were obtained. Their morphologies include extended diffuse, dense, isolated, cometary, and filament, of which the last is the majority. Twenty cores are starless, and only seven cores seem to be in a gravitationally bound state. Planck cold clumps are the most quiescent among the samples of weak red IRAS, infrared dark clouds, UC HII candidates, extended green objects, and methanol maser sources, suggesting that Planck cold clumps have expanded the horizon of cold astronomy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/3619
- Title:
- Planck ERCSC sources with 100 GHz flux excess
- Short Name:
- J/MNRAS/458/3619
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Planck Early Release Compact Source Catalogue (ERCSC) includes nine lists of highly reliable sources, individually extracted at each of the nine Planck frequency channels. To facilitate the study of the Planck sources, especially their spectral behaviour across the radio/infrared frequencies, we provide a 'bandmerged' catalogue of the ERCSC sources. This catalogue consists of 15191 entries, with 79 sources detected in all nine frequency channels of Planck and 6818 sources detected in only one channel. We describe the bandmerging algorithm, including the various steps used to disentangle sources in confused regions. The multifrequency matching allows us to develop spectral energy distributions of sources between 30 and 857GHz, in particular across the 100GHz band, where the energetically important CO J=1->0 line enters the Planck bandpass. We find ~3{sigma}-5{sigma} evidence for contribution to the 100GHz intensity from foreground CO along the line of sight to 147 sources with |b|>{30deg}. The median excess contribution is 4.5+/-0.9 per cent of their measured 100 GHz flux density which cannot be explained by calibration or beam uncertainties. This translates to 0.5+/-0.1K.km/s of CO which must be clumped on the scale of the Planck 100GHz beam, i.e. ~10-arcmin. If this is due to a population of low-mass (~15M_{sun}_) molecular gas clumps, the total mass in these clumps may be more than 2000 M_{sun}_. Further, high-spatial-resolution, ground-based observations of the high-latitude sky will help shed light on the origin of this diffuse, clumpy CO emission.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/76.109
- Title:
- Planck maps spots near RCR sources
- Short Name:
- J/other/AstBu/76
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The spectral properties of the inhomogeneities of the microwave background on Planck multi-frequency maps that are distant from the sources of the RCR catalog by the half-width of the power beam pattern of the high-frequency Planck complex (+/-2.5 arcmin), as well as the spectral features of the sources depending on the presence of positive spots near them, are studied. About 830 objects of the catalog were examined for the detection of spots with positive amplitudes near them. The features that indicate the connection of positive peaks on the Planck maps with the nearest radio sources are revealed. First, it is the excess of the number of RCR sources with flat and normal spectra, near which there are spots, over the number of sources with steep spectra. Secondly, the number of spots with positive amplitude on Planck maps that coincide within +/-2.5 arcmin with the coordinates of source-free areas on NVSS, FIRST maps and have the same sizes is on average almost one and a half times less than the number of spots that coincide with RCR objects. It is shown that RCR objects, near which there are no spots, have steeper spectra compared to the spectra of sources, near which spots are detected. The distribution of the spectral indices of spots in the range of 30--217 GHz was close to the distribution of the spectral indices of RCR sources in the range of 100MHz-8.5GHz and their median values almost coincided. This may indicate that the positive fluctuations on the Planck maps detected near RCR objects in the range of 30-217GHz are synchrotron in nature and may be associated with these objects. They can be manifestations of these objects or manifestations of their host galaxies and their environment in the submillimeter range. In the range of 353-857GHz, some of the detected spots can be classified as dusty. The spectra of RCR sources, near which such spots were detected, were steeper than the spectra of RCR objects, near which spots were detected only in the frequency channels 30-217GHz. The steeper the spectrum of the RCR object in the range of 100MHz-8.5GHz, the greater the value of the positive spectral index of the nearest spot in the range of 353-857GHz. The spots, whose two-frequency spectral indices indicate their dusty nature, may be associated with the high dust content in the host galaxies of RCR objects and the processes of star formation in them. It is also possible that the rise in the spectra at high frequencies may be caused by the presence of a signal from cold galactic dust on the frequency maps.
