- ID:
- ivo://CDS.VizieR/J/A+A/641/A17
- Title:
- Musca APEX 12CO(2-1), 12CO(3-2) & 12CO(4-3) data
- Short Name:
- J/A+A/641/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations with the Herschel Space Telescope have established that most star forming gas is organised in filaments, a finding that is supported by numerical simulations of the supersonic interstellar medium (ISM) where dense filamentary structures are ubiquitous. We aim to understand the formation of these dense structures by performing observations covering the ^12^CO(4-3), ^12^CO(3-2), and various CO(2-1) isotopologue lines of the Musca filament, using the APEX telescope. The observed CO intensities and line ratios cannot be explained by PDR (photodissociation region) emission because of the low ambient far-UV field that is strongly constrained by the non-detections of the [CII] line at 158um and the [OI] line at 63um, observed with the upGREAT receiver on SOFIA, as well as a weak [CI] 609um line detected with APEX. We propose that the observations are consistent with a scenario in which shock excitation gives rise to warm and dense gas close to the highest column density regions in the Musca filament. Using shock models, we find that the CO observations can be consistent with excitation by J-type low-velocity shocks. A qualitative comparison of the observed CO spectra with synthetic observations of dynamic filament formation simulations shows a good agreement with the signature of a filament accretion shock that forms a cold and dense filament from a converging flow. The Musca filament is thus found to be dense molecular post-shock gas. Filament accretion shocks that dissipate the supersonic kinetic energy of converging flows in the ISM may thus play a prominent role in the evolution of cold and dense filamentary structures.
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- ID:
- ivo://CDS.VizieR/J/A+A/631/A110
- Title:
- N131 bubble CO (3-2), (2-1) and (1-0) observations
- Short Name:
- J/A+A/631/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- N131 is a typical infrared dust bubble showing an expanding ringlike shell. We study what kinds of CO line ratios can be used to trace the interaction in the expanding bubble. We carry out new CO (3-2) observations towards bubble N131 using JCMT 15-m telescope, and derive line ratios by combining with our previous CO (2-1) and CO (1-0) data from IRAM 30-m observations. To trace the interaction between the molecular gas and the ionized gas in the HII region, we use RADEX to model the dependence of CO line ratios on kinetic temperature and H_2_ volume density, and examine the abnormal line ratios based on other simulations. We present CO (3-2), CO (2-1), and CO (1-0) integrated intensity maps convolved to the same angular resolution (22.5"). The three different CO transition maps show apparently similar morphology. The line ratios of W_CO_(3-2)/W_CO_(2-1) mostly range from 0.2 to 1.2 with a median of 0.54+/-0.12, while the line ratios of W_CO_(2-1)/W_CO_(1-0) range from 0.5 to 1.6 with a median of 0.84+/-0.15. The high CO line ratios W_CO_(3-2)/W_CO_(2-1)>0.8 and W_CO_(2-1)/W_CO_(1-0)>1.2 are beyond the threshold predicted by numerical simulations based on the assumed density-temperature structure for the inner rims of ringlike shell, where are the compressed areas in bubble N131. These high CO integrated intensity ratios, such as W_CO_(3-2)/W_CO_(2-1)>0.8 and W_CO_(2-1)/W_CO_(1-0)>1.2, can be used as a tracer of gas compressed regions with a relatively high temperature and density. This further suggests that the non-Gaussian part of the line-ratio distribution can be used to trace the interaction between the molecular gas and the hot gas in the bubble.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A117
- Title:
- N131 bubble CO integrated intensity maps
- Short Name:
- J/A+A/585/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- OB-type stars have strong ionizing radiation and drive energetic winds. The ultraviolet radiation from ionizing stars may heat dust and ionize gas to sweep up an expanding bubble shell. This shell may be the result of feedback leading to a new generation of stars. N131 is an infrared dust bubble residing in a molecular filament. We study the formation and fragmentation of this bubble with multiwavelength dust and gas observations. Towards the bubble N131, we analysed archival multiwavelength observations including 3.6, 4.5, 5.8, 8.0, 24, 70, 160, 250, 350, 500um, 1.1mm, and 21cm. In addition, we performed new observations of CO (2-1), CO (1-0), and ^13^CO (1-0) with the IRAM 30m telescope.
- ID:
- ivo://CDS.VizieR/J/ApJ/854/154
- Title:
- N159 ^12^CO and ^13^CO (2-1) clumps
- Short Name:
- J/ApJ/854/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The N159 star-forming region is one of the most massive giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC). We show the ^12^CO, ^13^CO, CS molecular gas lines observed with ALMA in N159 west (N159W) and N159 east (N159E). We relate the structure of the gas clumps to the properties of 24 massive young stellar objects (YSOs) that include 10 newly identified YSOs based on our search. We use dendrogram analysis to identify properties of the molecular clumps, such as flux, mass, linewidth, size, and virial parameter. We relate the YSO properties to the molecular gas properties. We find that the CS gas clumps have a steeper size-linewidth relation than the ^12^CO or ^13^CO gas clumps. This larger slope could potentially occur if the CS gas is tracing shocks. The virial parameters of the ^13^CO gas clumps in N159W and N159E are low (<1). The threshold for massive star formation in N159W is 501M_{sun}_/pc^2^, and the threshold for massive star formation in N159E is 794M_{sun}_/pc^2^. We find that ^13^CO is more photodissociated in N159E than N159W. The most massive YSO in N159E has cleared out a molecular gas hole in its vicinity. All the massive YSO candidates in N159E have a more evolved spectral energy distribution type in comparison to the YSO candidates in N159W. These differences lead us to conclude that the giant molecular cloud complex in N159E is more evolved than the giant molecular cloud complex in N159W.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A135
- Title:
- Nearby AGN ^12^CO and H{alpha} maps
- Short Name:
- J/A+A/577/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the relation between star formation rate (SFR) surface density ({Sigma}_SFR_) and mass surface density of molecular gas ({Sigma}_H2_), commonly referred to as the Kennicutt-Schmidt (K-S) relation, at its intrinsic spatial scale, i.e. the size of giant molecular clouds (~10-150pc), in the central, high-density regions of four nearby low-luminosity active galactic nuclei (AGN). These are AGN extracted from NUclei of GAlaxies (NUGA) survey. This study is aimed at investigating the correlations and slopes of the K-S relation, as a function of spatial resolution and of different ^12^CO emission lines used to trace {Sigma}_H2_, and testing its validity in the high-density central regions of spiral galaxies. We used interferometric IRAM ^12^CO(1-0) and ^12^CO(2-1), and SMA ^12^CO(3-2) emission line maps to derive {Sigma}_H2_ and HS T-H{alpha} to estimate {Sigma}_SFR_.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A83
- Title:
- NGC 1566 ALMA and Gemini-GMOS/IFU datacubes
- Short Name:
- J/A+A/621/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tracing nuclear inflows and outflows in AGNs, determining the mass of gas involved in them, and their impact on the host galaxy and nuclear black hole requires 3-D imaging studies of both the ionized and molecular gas. We map the distribution and kinematics of molecular and ionized gas in a sample of active galaxies to quantify the nuclear inflows and outflows. Here, we analyze the nuclear kinematics of NGC 1566 via ALMA observations of the CO J:2-1 emission at 24pc spatial and ~2.6km/s spectral resolution, and Gemini-GMOS/IFU observations of ionized gas emission lines and stellar absorption lines at similar spatial resolution, and 123km/s of intrinsic spectral resolution. The morphology and kinematics of stellar, molecular (CO), and ionized ([NII]) emission lines are compared to the expectations from rotation, outflows, and streaming inflows. While both ionized and molecular gas show rotation signatures, there are significant non-circular motions in the innermost 200pc and along spiral arms in the central kpc (CO). The nucleus shows a double-peaked CO profile (full width at zero intensity of 200km/s), and prominent (~80km/s) blue- and redshifted lobes are found along the minor axis in the inner arcseconds. Perturbations by the large-scale bar can qualitatively explain all features in the observed velocity field. We thus favor the presence of a molecular outflow in the disk with true velocities of ~180km/s in the nucleus and decelerating to 0 by ~72pc. The implied molecular outflow rate is 5.6M_{Sun}_/yr, with this gas accumulating in the nuclear 2" arms. The ionized gas kinematics support an interpretation of a similar but more spherical outflow in the inner 100pc, with no signs of deceleration. There is some evidence of streaming inflows of ~50km/s along specific spiral arms, and the estimated molecular mass inflow rate, ~0.1M_{Sun}_/yr, is significantly higher than the SMBH accretion rate (dM/dt=4.8x10^-5^M_{Sun}_/yr).
- 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/645/A111
- Title:
- NGC 4654 CO(2-1) data cube
- Short Name:
- J/A+A/645/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 4654 is a Virgo galaxy seen almost face-on, which undergoes nearly edge-on gas ram pressure stripping and a fly-by gravitational interaction with another massive galaxy, NGC 4639. NGC 4654 shows a strongly compressed gas region near the outer edge of the optical disk, with HI surface densities (HSDR), exceeding the canonical value of 10-15M_{sun}_/pc^2^. New IRAM 30m HERA CO(2-1) data of NGC 4654 are used to study the physical conditions of the ISM. The CO-to-H_2_ conversion factor was estimated and found to be one to two times the Galactic value with significant decrease in the ratio between the molecular fraction and the total ISM pressure in the HSDR, self-gravitating gas, a Toomre parameter below Q=1 and star-formation efficiency 1.5-2 times higher. Analytical models were used to reproduce radial profiles of the SFR and the atomic and molecular surface densities. A Toomre parameter of Q~0.8 combined with an increase in the velocity dispersion of {DELTA}_vdisp_~5km/s are necessary conditions to simultaneously reproduce the gas surface densities and the SFR. A dynamical model was used to reproduce the gas distribution of NGC 4654. The comparison between the velocity dispersion given by the moment 2 map and the intrinsic 3D velocity dispersion from the model were used to discriminate between regions of broader linewidths caused by a real increase in the velocity dispersion and those caused by an unresolved velocity gradient only. We found that the 5km/s increase in the intrinsic velocity dispersion is compatible with observations. During a period of gas compression through external interactions, the gas surface density is enhanced, leading to an increased SFR and stellar feedback. Under the influence of stellar feedback, the gas density increases only moderately. The stellar feedback acts as a regulator of star-formation, increasing the turbulent velocity within the region.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A85
- Title:
- NGC3627S and NGC3627N CO(1-0) data cubes
- Short Name:
- J/A+A/597/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To gain insight into the expected gas dynamics at the interface of the Galactic bar and spiral arms in our own MilkyWay galaxy, we examine as an extragalactic counterpart the evidence for multiple distinct velocity components in the cold, dense molecular gas populating a comparable region at the end of the bar in the nearby galaxy NGC 3627. We assemble a high resolution view of molecular gas kinematics traced by CO(2-1) emission and extract line-of-sight velocity profiles from regions of high and low gas velocity dispersion. The high velocity dispersions arise with often double-peaked or multiple line-profiles. We compare the centroids of the different velocity components to expectations based on orbital dynamics in the presence of bar and spiral potential perturbations. A model of the region as the interface of two gas-populated orbits families supporting the bar and the independently rotating spiral arms provides an overall good match to the data. An extent of the bar to the corotation radius of the galaxy is favored. Using NGC 3627 as an extragalactic example, we expect situations like this to favor strong star formation events such as observed in our own Milky Way since gas can pile up at the crossings between the orbit families. The relative motions of the material following these orbits is likely even more important for the build up of high density in the region. The surface densities in NGC 3627 are also so high that shear at the bar end is unlikely to significantly weaken the star formation activity. We speculate that scenarios in which the bar and spiral rotate at two different pattern speeds may be the most favorable for intense star formation at such interfaces.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/156
- Title:
- Nobeyama 45m Cygnus-X CO. II. C180 clumps
- Short Name:
- J/ApJ/883/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the statistical physical properties of the C^18^O(J=1-0) clumps present in a prominent cluster-forming region, Cygnus X, using the data set obtained by the Nobeyama 45m radio telescope. This survey covers 9deg^2^ of the northern and southern regions of Cygnus X, and, in total, 174 C^18^O clumps are identified using the dendrogram method. Assuming a distance of 1.4kpc, these clumps have radii of 0.2-1pc, velocity dispersions of <2.2km/s, gas masses of 30-3000M_{sun}_, and H_2_ densities of (0.2-5.5)x10^4^cm^-3^. We confirm that the C^18^O clumps in the northern region have a higher H_2_ density than those in the southern region, supporting the existence of a difference in the evolutionary stages, consistent with the star-formation activity of these regions. The difference in the clump properties of the star-forming and starless clumps is also confirmed by the radius, velocity dispersion, gas mass, and H_2_ density. The average virial ratio of 0.3 supports that these clumps are gravitationally bound. The C^18^O clump mass function shows two spectral index components, {alpha}=-1.4 in 55-140M_{sun}_ and {alpha}=-2.1 in >140M_{sun}_, which are consistent with the low- and intermediate-mass parts of the Kroupa's initial mass function. The spectral index of the star-forming clumps >140M_{sun}_ is consistent with that of the starless clumps ranging from 55-140M_{sun}_, suggesting that the latter will evolve into star-forming clumps while retaining the gas accretion. Assuming a typical star-formation efficiency of molecular clumps (10%), about 10 C^18^O clumps having a gas mass of >10^3^M_{sun}_ will evolve into open clusters containing one or more OB stars.
