- ID:
- ivo://CDS.VizieR/J/A+A/635/A2
- Title:
- NGC6334 ALMA 87.6GHz continuum emission map
- Short Name:
- J/A+A/635/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to characterise certain physical properties of high-mass star-forming sites in the NGC6334 molecular cloud, such as the core mass function (CMF), spatial distribution of cores, and mass segregation. We used the Atacama Large Millimetre/sub-millimetre Array (ALMA) to image the embedded clusters NGC6334-I and NGC6334-I(N) in the continuum emission at 87.6GHz. We achieved a spatial resolution of 1300au, enough to resolve different compact cores and fragments, and to study the properties of the clusters. We detected 142 compact sources distributed over the whole surveyed area. The ALMA compact sources are clustered in different regions. We used different machine-learning algorithms to identify four main clusters: NGC6334-I, NGC6334-I(N), NGC6334-I(NW), and NGC6334-E. The typical separations between cluster members range from 4000au to 12000au. These separations, together with the core masses (0.1-100M_{sun}_), are in agreement with the fragmentation being controlled by turbulence at scales of 0.1pc. We find that the CMFs show an apparent excess of high-mass cores compared to the stellar Initial Mass Function. We evaluated the effects of temperature and unresolved multiplicity on the derived slope of the CMF. Based on this, we conclude that the excess of high-mass cores might be spurious and due to inaccurate temperature determinations and/or resolution limitations. We searched for evidence of mass segregation in the clusters and we find that clusters NGC6334-I and NGC6334-I(N) show hints of segregation with the most massive cores located in the centre of the clusters. We searched for correlations between the physical properties of the four embedded clusters and their evolutionary stage (based on the presence of Hii regions and infrared sources). NGC6334-E appears as the most evolved cluster, already harboring a well-developed Hii region. NGC6334-I is the second-most evolved cluster with an ultra-compact Hii region. NGC6334-I(N) contains the largest population of dust cores distributed in two filamentary structures and no dominant Hii region. Finally, NGC6334-I(NW) is a cluster of mainly low-mass dust cores with no clear signs of massive cores or Hii regions.We find a larger separation between cluster members in the more evolved clusters favoring the role of gas expulsion and stellar ejection with evolution. The mass segregation, seen in the NGC6334-I and NGC6334-I(N) clusters, suggests a primordial origin for NGC6334-I(N). In contrast, the segregation in NGC6334-I might be due to dynamical effects. Finally, the lack of massive cores in the most evolved cluster suggests that the gas reservoir is already exhausted, while the less evolved clusters still have a large gas reservoir along with the presence of massive cores. In general, the fragmentation process of NGC6334 at large scales (from filament to clump, i.e. at about 1pc) is likely governed by turbulent pressure, while at smaller scales (scale of cores and sub-fragments, i.e. a few hundred au) thermal pressure starts to be more significant.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/622/A8
- Title:
- NGC 3184, 4736, 5055 and 5194 LOFAR & WSRT maps
- Short Name:
- J/A+A/622/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio continuum (RC) emission in galaxies allows us to measure star formation rates (SFRs) unaffected by extinction due to dust, of which the low-frequency part is uncontaminated from thermal (free-free) emission. We calibrate the conversion from the spatially resolved 140MHz RC emission to the SFR surface density (SFR) at 1kpc scale. Radio spectral indices give us, by means of spectral ageing, a handle on the transport of cosmic rays using the electrons as a proxy for GeV nuclei. We used recent observations of three galaxies (NGC 3184, 4736, and 5055) from the LOFAR Two-metre Sky Survey (LoTSS), and archival LOw Frequency ARay (LOFAR) data of NGC 5194. Maps were created with the facet calibration technique and converted to radio {Sigma}SFR maps using the Condon relation. We compared these maps with hybrid {Sigma}SFR maps from a combination of GALEX far-ultraviolet and Spitzer 24um data using plots tracing the relation at the highest angular resolution allowed by our data at 1.2x1.2-kpc^2^ resolution.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1093
- Title:
- NGC7332/7339 and NGC 1156 HI sources from AGES
- Short Name:
- J/AJ/140/1093
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two 5deg^2^ regions around the NGC 7332/9 galaxy pair and the isolated galaxy NGC 1156 have been mapped in the 21cm line of neutral hydrogen (HI) with the Arecibo L-band Feed Array out to a redshift of ~0.065 (~20000km/s) as part of the Arecibo Galaxy Environment Survey. One of the aims of this survey is to investigate the environment of galaxies by identifying dwarf companions and interaction remnants; both of these areas provide the potential for such discoveries. The neutral hydrogen observations were complemented by optical and radio follow-up observations with a number of telescopes. A total of 87 galaxies were found, of which 39 (45%) were previously catalogued and 15 (17%) have prior redshifts. Two dwarf galaxies have been discovered in the NGC 7332 group and a single dwarf galaxy in the vicinity of NGC 1156. A parallel optical search of the area revealed one further possible dwarf galaxy near NGC 7332.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A12
- Title:
- NGC 891 and NGC 4565 radio images
- Short Name:
- J/A+A/632/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cosmic-ray electrons (CREs) originating from the star-forming discs of spiral galaxies frequently form extended radio haloes that are best observable in edge-on galaxies, where their properties can be directly investigated as a function of vertical height above the disc. For the present study, we selected two nearby edge-on galaxies from the Continuum Halos in Nearby Galaxies - an EVLA Survey (CHANG-ES), NGC 891 and 4565, which differ largely in their detectable halo extent and their star- formation rates (SFRs). Our aim is to figure out how such differences are related to the (advective and/or diffusive) CRE transport in the disc and in the halo. We use wide-band 1.5 and 6GHz Very Large Array (VLA) observations obtained in the B, C, and D configurations, and combine the 6GHz images with Effelsberg observations to correct for missing short spacings. After subtraction of the thermal emission, we investigate the spatially resolved synchrotron spectral index distribution in terms of CRE spectral ageing. We further compute total magnetic field strengths assuming equipartition between the cosmic-ray (CR) energy density and the magnetic field, and measure synchrotron scale heights at both frequencies. Based on the fitted vertical profiles of the synchrotron intensity and on the spectral index profile between 1.5 and 6GHz, we create purely advective and purely diffusive CRE transport models by numerically solving the 1D diffusion-loss equation. In particular, we investigate for the first time the radial dependence of synchrotron and magnetic field scale heights, advection speeds, and diffusion coefficients, whereas previous studies of these two galaxies only determined global values of these quantities.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A151
- Title:
- NGC 7213 central region molecular gas
- Short Name:
- J/A+A/641/A151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength study (from X-ray to mm) of the nearby low-luminosity active galactic nucleus (LLAGN) NGC 7213. We combine the information from the different bands to characterise the source in terms of contribution from the AGN and the host-galaxy interstellar medium (ISM). This approach allows us to provide a coherent picture of the role of the AGN and its impact, if any, on the star formation and molecular gas properties of the host galaxy. We focused our study on archival ALMA Cycle 1 observations, where the CO(2-1) emission line has been used as a tracer of the molecular gas. Using the 3DBarolo code on ALMA data, we performed the modelling of the molecular gas kinematics traced by the CO(2-1) emission, finding a rotationally dominated pattern. The molecular gas mass of the host galaxy was estimated from the integrated CO(2-1) emission line obtained with APEX data, assuming an alpha_co conversion factor. Had we used the ALMA data, we would have underestimated the gas masses by a factor ~3, given the filtering out of the large-scale emission in interferometric observations. We also performed a complete X-ray spectral analysis on archival observations, revealing a relatively faint and unobscured AGN. The AGN proved to be too faint to significantly affect the properties of the host galaxy, such as star formation activity and molecular gas kinematics and distribution.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A61
- Title:
- NGC1068 CO and HCO images
- Short Name:
- J/A+A/632/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the fueling and the feedback of nuclear activity in the Seyfert 2 galaxy NGC1068, by studying the distribution and kinematics of molecular gas in the torus and its connections. We use ALMA to image the emission of a set of molecular gas tracers in the circumnuclear disk (CND) and the torus of the galaxy using the CO(2-1), CO(3-2) and HCO^+^(4-3) lines with spatial resolutions ~0.03"-0.09"(2-6pc). ALMA resolves the CND as an asymmetric ringed disk of D~400pc-size and mass of ~1.4x10^8^M_{sun}_. The inner edge of the ring is associated with edge-brightened arcs of NIR polarized emission identified with the working surface of the AGN ionized wind. ALMA proves the existence of a molecular torus of M_torus ~3x10^5^M_{sun}_, which extends over a large range of spatial scales D=10-30pc around the central engine. The new observations evidence the density radial stratification of the torus: the HCO^+^(4-3) torus, with a full size D=11pc, is a factor of 2-3 smaller than its CO(2-1) and CO(3-2) counterparts, which have full-sizes D=26pc and D=28pc, respectively. The torus is connected to the CND through a network of gas streamers. The kinematics of molecular gas show strong departures from circular motions in the torus, the gas streamers, and the CND. These velocity distortions are interconnected and are part of a 3D outflow that reflects the effects of AGN feedback on the kinematics of molecular gas across a wide range of spatial scales. We conclude that a wide-angle AGN wind launched from the accretion disk is impacting a sizeable fraction of the gas inside the torus (~0.4-0.6xM_torus_). However, a large gas reservoir (~1.2-1.8x10^5^M_{sun}_) close to the equatorial plane of the torus remains unaffected by the AGN wind and can continue fueling the AGN for ~1-4Myr. AGN fueling seems nevertheless thwarted on intermediate scales (15pc<r<50pc).
- ID:
- ivo://CDS.VizieR/J/A+A/632/A83
- Title:
- NGC 6334 filament with ALMA
- Short Name:
- J/A+A/632/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Herschel imaging surveys of galactic interstellar clouds support a paradigm for low-mass star formation in which dense molecular filaments play a crucial role. The detailed fragmentation properties of star-forming filaments remain poorly understood, however, and the validity of the filament paradigm in the intermediate- to high-mass regime is still unclear. Here, following up on an earlier 350um dust continuum study with the ArTeMiS camera on the APEX telescope, we investigate the detailed density and velocity structure of the main filament in the high-mass star-forming region NGC 6334. We conducted ALMA Band 3 observations in the 3.1mm continuum and of the N_2_H^+^(1-0), HC_5_N(36-35), HNC(1-0), HC_3_N(10-9), CH_3_CCH(6-5), and H_2_CS(3-2) lines at an angular resolution of 300, corresponding to 0.025 pc at a distance of 1.7kpc. The NGC 6334 filament was detected in both the 3.1mm continuum and the N_2_H^+^, HC_3_N, HC_5_N, CH_3_CCH, and H_2_CS lines with ALMA. We identified twenty-six compact (<0.03pc) dense cores at 3.1mm and five velocity-coherent fiber-like features in N_2_H^+^ within the main filament. The typical length (~0.5pc) of, and velocity difference (~0.8km/s) between, the fiber-like features of the NGC 6334 filament are reminiscent of the properties for the fibers of the low-mass star-forming filament B211/B213 in the Taurus cloud. Only two or three of the five velocity-coherent features are well aligned with the NGC 6334 filament and may represent genuine, fiber sub-structures; the other two features may trace accretion flows onto the main filament. The mass distribution of the ALMA 3.1mm continuum cores has a peak at 10 M, which is an order of magnitude higher than the peak of the prestellar core mass function in nearby, low-mass star-forming clouds. The cores can be divided into seven groups, closely associated with dense clumps seen in the ArTeMiS 350um data. The projected separation between ALMA dense cores (0.03-0.1pc) and the projected spacing between ArTeMiS clumps (0.2-0.3pc) are roughly consistent with the effective Jeans length (0.08+/-0.03pc) in the filament and a physical scale of about four times the filament width, respectively, if the inclination angle of the filament to line of sight is ~30{deg}. These two distinct separation scales are suggestive of a bimodal fragmentation process in the filament. Despite being one order of magnitude denser and more massive than the Taurus B211/B213 filament, the NGC 6334 filament has a density and velocity structure that is qualitatively very similar. The main difference is that the dense cores embedded in the NGC 6334 filament appear to be an order of magnitude denser and more massive than the cores in the Taurus filament. This suggests that dense molecular filaments may evolve and fragment in a similar manner in low- and high-mass star-forming regions, and that the filament paradigm may hold in the intermediate-mass (if not high-mass) star formation regime.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A65
- Title:
- NGC 7129 FIRS 2 interferometric 1-D spectrum
- Short Name:
- J/A+A/568/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 7129 FIRS 2 (hereafter FIRS 2) is an intermediate-mass (2 to 8M_{sun}_) protostar located at a distance of 1250pc. High spatial resolution observations are required to resolve the hot core at its center. We present a molecular survey from 218200MHz to 221800MHz carried out with the IRAM Plateau de Bure Interferometer. These observations were complemented with a long integration single-dish spectrum taken with the IRAM 30m telescope. We used a Local Thermodynamic Equilibrium (LTE) single temperature code to model the whole dataset. The interferometric spectrum is crowded with a total of ~300 lines from which a few dozens remain unidentified yet. The spectrum has been modeled with a total of 20 species and their isomers, isotopologues and deuterated compounds. Complex molecules like methyl formate (CH_3_OCHO), ethanol (CH_3_CH_2_OH),g lycolaldehyde (CH_2_OHCHO), acetone (CH_3_COCH_3_), dimethyl ether (CH_3_OCH_3_), ethyl cyanide (CH_3_CH_2_CN) and the aGg' conformer of ethylene glycol (aGg'-(CH_2_OH)_2_) are among the detected species. The detection of vibrationally excited lines of CH_3_CN, CH_3_OCHO, CH_3_OH, OCS, HC_3_N and CH_3_CHO proves the existence of gas and dust at high temperatures. In fact, the gas kinetic temperature estimated from the vibrational lines of CH_3_CN, ~405K, is similar to that measured in massive hot cores. Our data allow an extensive comparison of the chemistry in FIRS 2 and the Orion hot core. We find a quite similar chemistry in FIRS 2 and Orion. Most of the studied fractional molecular abundances agree within a factor of 5. Larger differences are only found for the deuterated compounds D_2_CO and CH_2_DOH and a few molecules (CH_3_CH_2_CN, SO_2_, HNCO and CH_3_CHO). Since the physical conditions are similar in both hot cores, only different initial conditions (warmer pre-collapse phase in the case of Orion) and/or different crossing time of the gas in the hot core can explain this behavior.
- ID:
- ivo://CDS.VizieR/J/MNRAS/379/275
- Title:
- NGC 5033 1.4GHz radio emission
- Short Name:
- J/MNRAS/379/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new continuum VLA observations of the nearby Sy 1.5 galaxy NGC 5033, made at 4.9- and 8.4-GHz on 2003 April 8. Combined with VLA archival observations at 1.4- and 4.9-GHz made on 1993 August 7, 1999 August 29 and 1999 October 31, we sample the galaxy radio emission at scales ranging from the nuclear regions (<100pc) to the outer regions of the disc (~40kpc). The high-resolution VLA images show a corejet structure for the Sy 1.5 nucleus.
- ID:
- ivo://CDS.VizieR/J/A+A/600/A6
- Title:
- NGC628 3.1GHz total intensity & polarised images
- Short Name:
- J/A+A/600/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnetic fields are essential to fully understand the interstellar medium (ISM) and its role in the disk-halo interface of galaxies is still poorly understood. Star formation is known to expel hot gas vertically into the halo and these outflows have important consequences for mean-field dynamo theory in that they can be efficient in removing magnetic helicity. We perform new observations of the nearby face-on spiral galaxy NGC 628 with the Karl G. Jansky Very Large Array (JVLA) at S-band and the Effelsberg 100-m telescope at frequencies of 2.6GHz and 8.35GHz. We obtain some of the most sensitive radio continuum images in both total and linearly polarised intensity of any external galaxy observed so far in addition to high-quality images of Faraday depth and polarisation angle from which we obtained evidence for drivers of magnetic turbulence in the disk-halo connection. Such drivers include a superbubble detected via a significant Faraday depth gradient coinciding with a HI hole. We observe an azimuthal periodic pattern in Faraday depth with a pattern wavelength of 3.7+/-0.1kpc, indicating Parker instabilities. The lack of a significant anti-correlation between Faraday depth and magnetic pitch angle indicates that these loops are vertical in nature with little helical twisting, unlike in IC 342. We find that the magnetic pitch angle is systematically larger than the morphological pitch angle of the polarisation arms which gives evidence for the action of a large-scale dynamo where the regular magnetic field is not coupled to the gas flow and obtains a significant radial component. We additionally discover a lone region of ordered magnetic field to the north of the galaxy with a high degree of polarisation and a small pitch angle, a feature that has not been observed in any other galaxy so far and is possibly caused by an asymmetric HI hole.
