- ID:
- ivo://CDS.VizieR/J/A+A/641/A155
- Title:
- CO+[CI] emission in distant galaxies
- Short Name:
- J/A+A/641/A155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detection of multiple carbon monoxide CO line transitions with ALMA in a few tens of infrared-selected galaxies on and above the main sequence at z=1.1-1.7. We reliably detected the emission of CO(5-4), CO(2-1), and CO(7-6)+[CI](2-1) in 50, 33, and 13 galaxies, respectively, and we complemented this information with available CO(4-3) and [CI](1-0) fluxes for part of the sample, and by modeling of the optical-to-millimeter spectral energy distribution. We retrieve a quasi-linear relation between LIR and CO(5-4) or CO(7-6) for main-sequence galaxies and starbursts, corroborating the hypothesis that these transitions can be used as star formation rate (SFR) tracers. We find the CO excitation to steadily increase as a function of the star formation efficiency (SFE), the mean intensity of the radiation field warming the dust (<U>), the surface density of SFR (SigmaSFR), and, less distinctly, with the distance from the main sequence. This adds to the tentative evidence for higher excitation of the CO+[CI] spectral line energy distribution (SLED) of starburst galaxies relative to that for main-sequence objects, where the dust opacities play a minor role in shaping the high-J CO transitions in our sample. However, the distinction between the average SLED of upper main-sequence and starburst galaxies is blurred, driven by a wide variety of intrinsic shapes. Large velocity gradient radiative transfer modeling demonstrates the existence of a highly excited component that elevates the CO SLED of high-redshift main-sequence and starbursting galaxies above the typical values observed in the disk of the Milky Way. This excited component is dense and it encloses ~50% of the total molecular gas mass in main-sequence objects. We interpret the observed trends involving the CO excitation as to be mainly determined by a combination of large SFRs and compact sizes, as a large SigmaSFR is naturally connected with enhanced dense molecular gas fractions and higher dust and gas temperatures, due to increasing ultraviolet radiation fields, cosmic ray rates, as well as dust and gas coupling. We release the full data compilation and the ancillary information to the community.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/635/A131
- Title:
- 12CO/13CO ratio in 126 nearby galaxy centers
- Short Name:
- J/A+A/635/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ground-based measurements of 126 nearby galaxy centers in ^12^CO and 92 in ^13^CO in various low-J transitions. More than 60 galaxies were measured in at least four lines. The average relative intensities of the first four J ^12^CO transitions are 1.00:0.92:0.70:0.57. In the first three J transitions, the average ^12^CO-to-^13^CO intensity ratios are 13.0, 11.6, and 12.8, with individual values in any transition ranging from 5 to 25. The sizes of central CO concentrations are well defined in maps, but poorly determined by multi-aperture photometry. On average, the J=1-0 ^12^CO fluxes increase linearly with the size of the observing beam. CO emission covers only a quarter of the HI galaxy disks. Using radiative transfer models (RADEX), we derived model gas parameters. The assumed carbon elemental abundances and carbon gas depletion onto dust are the main causes of uncertainty. The new CO data and published [CI] and [CII] data imply that CO, C, and C^+^ each represent about one-third of the gas-phase carbon in the molecular interstellar medium. The mean beam-averaged molecular hydrogen column density is N(H_2_)=(1.5+/-0.2)10^21^cm^-2^. Galaxy center CO-to- H2 conversion factors are typically ten times lower than the 'standard' Milky Way X disk value, with a mean X(CO)=(1.9+/-0.2)10^19^cm^-2^/(K.km/s) and a dispersion 1.7. The corresponding [CI]-H_2_ factor is five times higher than X(CO), with X[CI]=(9+/-2)10^19^cm^-2^/(K.km/s). No unique conversion factor can be determined for [CII]. The low molecular gas content of galaxy centers relative to their CO intensities is explained in roughly equal parts by high central gas-phase carbon abundances, elevated gas temperatures, and large gas velocity dispersions relative to the corresponding values in galaxy disks.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A154
- Title:
- CO datacube abd spectra of UGC 10214
- Short Name:
- J/A+A/623/A154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Minor mergers play a crucial role in galaxy evolution. UGC 10214 (the Tadpole galaxy) is a prime example of this process in which a dwarf galaxy has interacted with a large spiral galaxy ~250 Myr ago and produced a perturbed disc and a giant tidal tail. We used a multi-wavelength dataset that partly consists of new observations (H{alpha}, HI, and CO) and partly of archival data to study the present and past star formation rate (SFR) and its relation to the gas and stellar mass at a spatial resolution down to 4 kpc. UGC 10214 is a high-mass (stellar mass M_*_=1.28x10^11^ M_{sun}_) galaxy with a low gas fraction (M_gas_/M_*_=0.24), a high molecular gas fraction (M_H2_/M_HI_=0.4), and a modest SFR (2-5 M_{sun}_/yr). The global SFR compared to its stellar mass places UGC 10214 on the galaxy main sequence (MS). The comparison of the molecular gas mass and current SFR gives a molecular gas depletion time of about ~2 Gyr (based on H{alpha}), comparable to those of normal spiral galaxies. Both from a comparison of the H{alpha} emission, tracing the current SFR, and far-ultraviolet (FUV) emission, tracing the recent SFR during the past tens of Myr, and also from spectral energy distribution fitting with CIGALE, we find that the SFR has increased by a factor of about 2-3 during the recent past. This increase is particularly noticeable in the centre of the galaxy where a pronounced peak of the H{alpha} emission is visible. A pixel-to-pixel comparison of the SFR, molecular gas mass, and stellar mass shows that the central region has had a depressed FUV-traced SFR compared to the molecular gas and the stellar mass, whereas the H{alpha}-traced SFR shows a normal level. The atomic and molecular gas distribution is asymmetric, but the position-velocity diagram along the major axis shows a pattern of regular rotation. We conclude that the minor merger has most likely caused variations in the SFR in the past that resulted in a moderate increase of the SFR, but it has not perturbed the gas significantly so that the molecular depletion time remains normal.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A126
- Title:
- CO in group-dominant ellipticals
- Short Name:
- J/A+A/618/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present IRAM 30m and APEX telescope observations of CO(1-0) and CO(2-1) lines in 36 group-dominant early-type galaxies, completing our molecular gas survey of dominant galaxies in the Complete Local-volume Groups Sample. We detect CO emission in 12 of the galaxies at >4{sigma} significance, with molecular gas masses in the range 0.01-6x10^8^M_{sun}_, as well as CO in absorption in the non-dominant group member galaxy NGC 5354. In total 21 of the 53 CLoGS dominant galaxies are detected in CO and we confirm our previous findings that they have low star formation rates (0.01-1M_{sun}_/yr) but short depletion times (<1Gyr) implying rapid replenishment of their gas reservoirs. Comparing molecular gas mass with radio luminosity, we find that a much higher fraction of our group-dominant galaxies (60+/-16%) are AGN-dominated than is the case for the general population of ellipticals, but that there is no clear connection between radio luminosity and the molecular gas mass. Using data from the literature, we find that at least 27 of the 53 CLoGS dominant galaxies contain HI, comparable to the fraction of nearby non-cluster early type galaxies detected in HI and significantly higher that the fraction in the Virgo cluster. We see no correlation between the presence of an X-ray detected intra-group medium and molecular gas in the dominant galaxy, but find that the HI-richest galaxies are located in X-ray faint groups. Morphological data from the literature suggests the cold gas component most commonly takes the form of a disk, but many systems show evidence of galaxy-galaxy interactions, indicating that they may have acquired their gas through stripping or mergers. We provide improved molecular gas mass estimates for two galaxies previously identified as being in the centres of cooling flows, NGC 4636 and NGC5846, and find that they are relatively molecular gas poor compared to our other detected systems.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A24
- Title:
- CO in HCG galaxies with enhanced warm H_2_
- Short Name:
- J/A+A/570/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxies in Hickson Compact Groups (HCGs) are believed to experience morphological transformations from blue, star-forming galaxies to red, early-type galaxies. Galaxies with a high ratio between the luminosities of the warm H_2_ to the 7.7micron PAH emission (so-called Molecular Hydrogen Emission Galaxies, MOHEGs) are predominantly in an intermediate phase, the green valley. Their enhanced H_2_ emission suggests that the molecular gas is affected in the transition. We study the properties of the molecular gas traced by CO in galaxies in HCGs with measured warm H_2_ emission in order to look for evidence of the perturbations affecting the warm H_2_ in the kinematics, morphology and mass of the molecular gas. We observed the CO(1-0) emission of 20 galaxies in HCGs and complemented our sample with 11 CO(1-0) spectra from the literature. Most of the galaxies have measured} warm H_2_ emission, and 14 of them are classified as MOHEGs. We mapped some of these galaxies in order to search for extra-galactic CO emission. We analyzed the molecular gas mass derived from CO(1-0), MH_2_, and its kinematics, and then compared it to the mass of the warm molecular gas, the stellar mass and star formation rate (SFR). Our results are the following. (i) The mass ratio between the CO-derived and the warm H_2_ molecular gas is in the same range as found for field galaxies. (ii) Some of the galaxies, mostly MOHEGs, have very broad CO linewidths of up to 1000km/s in the central pointing. The line shapes are irregular and show various components. (iii) In the mapped objects we found asymmetric distributions of the cold molecular gas. (iv) The star formation efficiency (=SFR/MH_2_) of galaxies in HCGs is very similar to isolated galaxies. No significant difference between MOHEGs and non-MOHEGs or between early-type and spiral galaxies has been found. In a few objects the SFE is significantly lower, indicating the presence of molecular gas that is not actively forming stars. (v) The molecular gas masses, MH_2_, and ratios MH_2_/Lk are lower in MOHEGs (predominantly early-types) than in non-MOHEGs (predominantly spirals). This trend remains when comparing MOHEGs and non-MOHEGs of the same morphological type. We found differences in the molecular gas properties of MOHEGs that support the view that they have suffered (or are presently suffering) perturbations of the molecular gas, as well as a decrease in the molecular gas content and associated SFR. Higher resolution observations of the molecular gas are needed to shed light on the nature of these perturbations and their cause.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/555
- Title:
- COLA. III. AGN in compact IR galaxies
- Short Name:
- J/ApJ/720/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from 4.8GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L_IR_=10^11.01^L_{sun}_) COLA (Compact Objects in Low-power AGNs) sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (~10^21^W/Hz) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.
657. Cold galaxies
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/2050
- Title:
- Cold galaxies
- Short Name:
- J/MNRAS/453/2050
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use 350 {mu}m angular diameter estimates from Planck to test the idea that some galaxies contain exceptionally cold (10-13 K) dust, since colder dust implies a lower surface brightness radiation field illuminating the dust, and hence a greater physical extent for a given luminosity. The galaxies identified from their spectral energy distributions as containing cold dust do indeed show the expected larger 350 {mu}m diameters. For a few cold dust galaxies where Herschel data are available, we are able to use submillimetre maps or surface brightness profiles to locate the cold dust, which as expected generally lies outside the optical galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A65
- Title:
- Cold gas properties of Herschel Reference Survey
- Short Name:
- J/A+A/564/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new ^12^CO(1-0) observations of 59 late-type galaxies belonging to the Herschel Reference Survey (HRS), a complete K-band-selected, volume-limited (15<=D<=25Mpc) sample of nearby galaxies spanning a wide range in morphological type and luminosity. We studied different recipes to correct single-beam observations of nearby galaxies of different sizes and inclinations for aperture effects. This was done by comparing single-beam and multiple-beam observations along the major axis, which were corrected for aperture effects using different empirical or analytical prescriptions, to integrated maps of several nearby galaxies, including edge-on systems observed by different surveys. The resulting recipe is an analytical function determined by assuming that late-type galaxies are 3D exponentially declining discs with a characteristic scale length r_CO_=0.2r_24.5_, where r_24.5_ is the optical, g- (or B-) band isophotal radius at the 24.5mag/arcsec^2^ (25mag/arcsec^2^), as well as a scale height z_CO_=1/100r_24.5_. Our new CO data are then combined with those available in the literature to produce the most updated catalogue of CO observations for the HRS, now including 225 out of the 322 galaxies of the complete sample. The 3D exponential disc integration is applied to all the galaxies of the sample to measure their total CO fluxes, which are later transformed into molecular gas masses using a constant and a luminosity-dependent X_CO_ conversion factor. We also collect HI data for 315 HRS galaxies from the literature and present it in a homogenised form.
659. COLD GASS survey
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/32
- Title:
- COLD GASS survey
- Short Name:
- J/MNRAS/415/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are conducting COLD GASS, a legacy survey for molecular gas in nearby galaxies. Using the IRAM 30-m telescope, we measure the CO(1-0) line in a sample of ~350 nearby (D_I_~=100-200Mpc), massive galaxies (log(M*/M_{sun}_)>10.0). The sample is selected purely according to stellar mass, and therefore provides an unbiased view of molecular gas in these systems. By combining the IRAM data with Sloan Digital Sky Survey (SDSS) photometry and spectroscopy, GALEX imaging and high-quality Arecibo HI data, we investigate the partition of condensed baryons between stars, atomic gas and molecular gas in 0.1-10L* galaxies. In this paper, we present CO luminosities and molecular hydrogen masses for the first 222 galaxies. Description: To overcome this issue, the GALEX Arecibo SDSS Survey (GASS; Catinella et al. 2010, Cat. J/MNRAS/403/683) was designed to measure the neutral hydrogen content for a large, unbiased sample of ~1000 massive galaxies (M*>10^10^M_{sun}_), via longer pointed observations. GASS is a large programme currently under way at the Arecibo 305-m telescope, and is producing some of the first unbiased atomic gas scaling relations in the nearby Universe (Catinella et al. 2010, Cat. J/MNRAS/403/683; Schiminovich et al., 2010MNRAS.408..919S; Fabello et al., 2011MNRAS.411..993F). We are in the process of constructing a CO Legacy Data base for the GASS survey (COLD GASS), measuring the molecular gas content of a significant subsample of the GASS galaxies. We will then be able to quantify the link between atomic gas, molecular gas and stars in these systems.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/2601
- Title:
- CO lines in luminous IR galaxies
- Short Name:
- J/MNRAS/426/2601
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results from a large molecular line survey of luminous infrared galaxies (LIRGs; L_IR_>~10^11^L_{sun}_) in the local Universe (z<=0.1), conducted during the last decade with the James Clerk Maxwell Telescope and the IRAM 30-m telescope. This work presents the CO and ^13^CO line data for 36 galaxies, further augmented by multi-J total CO line luminosities available for other infrared (IR) bright galaxies from the literature. This yields a combined sample of N=70 galaxies with the star formation (SF) powered fraction of their IR luminosities spanning L^(*)^IR_~10^10^-2x10^12^)L_{sun}_ and a wide range of morphologies.
