- ID:
- ivo://CDS.VizieR/J/ApJ/750/136
- Title:
- Molecular clouds in the Antennae from CO(2-1)
- Short Name:
- J/ApJ/750/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Super star clusters--extremely massive clusters found predominately in starburst environments--are essential building blocks in the formation of galaxies and thought to dominate star formation in the high-redshift universe. However, the transformation from molecular gas into these ultracompact star clusters is not well understood. To study this process, we used the Submillimeter Array and the Plateau de Bure Interferometer to obtain high angular resolution (~1.5" or 160pc) images of the Antennae overlap region in CO(2-1) to search for the molecular progenitors of the super star clusters. We resolve the molecular gas distribution into a large number of clouds, extending the differential cloud mass function down to a 5{sigma} completeness limit of 3.8x10^5^M_{sun}_. We identify a distinct break in the mass function around log M_mol_/M_{sun}_{approx}6.5, which separates the molecular clouds into two distinct populations. The smaller, less massive clouds reside in more quiescent areas in the region, while the larger, more massive clouds cluster around regions of intense star formation. A broken power-law fit to the mass function yields slopes of {alpha}=-1.39+/-0.10 and {alpha}=-1.44+/-0.14 for the low- and high-mass cloud population, well matched to the mass function found for super star clusters in the Antennae galaxies. We find large velocity gradients and velocity dispersions at the locations of intense star formation, suggestive of compressive shocks. It is likely that these environmental factors contribute to the formation of the observed massive molecular clouds and super star clusters in the Antennae galaxies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/901/L8
- Title:
- Molecular gas properties of 70 PHANGS-ALMA galaxies
- Short Name:
- J/ApJ/901/L8
- Date:
- 23 Feb 2022 00:10:50
- Publisher:
- CDS
- Description:
- Using the PHANGS-ALMA CO(2-1) survey, we characterize molecular gas properties on ~100pc scales across 102,778 independent sightlines in 70 nearby galaxies. This yields the best synthetic view of molecular gas properties on cloud scales across the local star-forming galaxy population obtained to date. Consistent with previous studies, we observe a wide range of molecular gas surface densities (3.4dex), velocity dispersions (1.7dex), and turbulent pressures (6.5dex) across the galaxies in our sample. Under simplifying assumptions about subresolution gas structure, the inferred virial parameters suggest that the kinetic energy of the molecular gas typically exceeds its self-gravitational binding energy at ~100pc scales by a modest factor (1.3 on average). We find that the cloud-scale surface density, velocity dispersion, and turbulent pressure (1) increase toward the inner parts of galaxies, (2) are exceptionally high in the centers of barred galaxies (where the gas also appears less gravitationally bound), and (3) are moderately higher in spiral arms than in inter-arm regions. The galaxy-wide averages of these gas properties also correlate with the integrated stellar mass, star formation rate, and offset from the star-forming main sequence of the host galaxies. These correlations persist even when we exclude regions with extraordinary gas properties in galaxy centers, which contribute significantly to the inter-galaxy variations. Our results provide key empirical constraints on the physical link between molecular cloud populations and their galactic environment.
- ID:
- ivo://CDS.VizieR/J/A+A/428/877
- Title:
- 4 nearby galaxies velocities & line-strengths
- Short Name:
- J/A+A/428/877
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of four nearby early-type galaxies previously known (Rest et al., 2001AJ....121.2431R) to have nuclear stellar disks using two instruments on-board the Hubble Space Telescope. We observed NGC 4128, NGC 4612, and NGC 5308 with the Wide Field Planetary Camera 2, and the same three galaxies, plus NGC 4570, with the Space Telescope Imaging Spectrograph. We have detected a red nucleus in NGC 4128, a blue nucleus in NGC 4621, and a blue disk in NGC 5308. Additionally, we have discovered a blue disk-like feature with position angle ~15{deg} from the major axis in NGC 4621. In NGC 5308 there is evidence for a blue region along the minor axis. We discovered a blue transient on the images of NGC 4128 at position 0.14" west and 0.32" north from the nucleus. The extracted kinematic profiles belong to two groups: fast (NGC 4570 and NGC 5308) and kinematically disturbed rotators (NGC 4128 and NGC 4621). We report the discovery of a kinematically decoupled core in NGC 4128. Galaxies have mostly old (10-14Gyr) stellar populations with large spread in metallicities (sub- to super-solar). We discuss the possible formation scenarios, including bar-driven secular evolution and the influence of mergers, which can explain the observed color and kinematic features.
- ID:
- ivo://CDS.VizieR/J/MNRAS/394/1249
- Title:
- New PNe in 6 early-type galaxies
- Short Name:
- J/MNRAS/394/1249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new planetary nebulae (PNe) positions, radial velocities and magnitudes for six early-type galaxies obtained with the Planetary Nebulae Spectrograph (PNS), along with derived two-dimensional velocity and velocity dispersion fields, and the {alpha} parameters (i.e. the number of PNe per unit luminosity). We also present new deep absorption-line long-slit kinematics for three galaxies in the sample, obtained with the FOcal Reducer and low dispersion Spectrograph (FORS2) at the Very Large Telescope (VLT).
- ID:
- ivo://CDS.VizieR/J/ApJ/773/L36
- Title:
- NGC 5128 globular cluster abundances
- Short Name:
- J/ApJ/773/L36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present [Fe/H], ages, and Ca abundances for an initial sample of 10 globular clusters in NGC 5128 obtained from high-resolution, high signal-to-noise ratio echelle spectra of their integrated light. All abundances and ages are obtained using our original technique for high-resolution integrated light abundance analysis of globular clusters. The clusters have a range in [Fe/H] between -1.6 and -0.2. In this sample, the average [Ca/Fe] for clusters with [Fe/H]<-0.4 is +0.37+/-0.07, while the average [Ca/Fe] in our Milky Way (MW) and M31 GC samples is +0.29+/-0.09 and +0.24+/-0.10, respectively. This may imply a more rapid chemical enrichment history for NGC 5128 than for either the MW or M31. This sample provides the first quantitative picture of the chemical history of NGC 5128 that is directly comparable to what is available for the MW. Data presented here were obtained with the MIKE echelle spectrograph on the Magellan Clay Telescope.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/105
- Title:
- NGC 6221 ionized gas kinematics
- Short Name:
- J/A+AS/131/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation curves and velocity dispersion profiles are presented for both the stellar and gaseous components along five different position angles (PA =5{deg}, 50{deg}, 95{deg}, 125{deg}, and 155{deg}) of the nearby barred spiral NGC 6221. The observed kinematics extends out to about 80'' from the nucleus. Narrow and broad-band imaging is also presented. The radial profiles of the fluxes ratio [NII] ({lambda} 6583.4{AA})/H{alpha} reveal the presence of a ring-like structure of ionized gas, with a radius of about 9'' and a deprojected circular velocity of about 280km/s. The analysis of the dynamics of the bar indicates this ring is related to the presence of an inner Lindblad resonance (ILR) at 1.3kpc. NGC 6221 is found to exhibit intermediate properties between those of the early-type barred galaxies: the presence of a gaseous ring at an ILR, the bar edge located between the ILR's and the corotation radius beyond the steep rising portion of the rotation curve, the dust-lane pattern, and those of the late-type galaxies: an almost exponential surface brightness profile, the presence of H{alpha} regions along all the bar, the spiral-arm pattern. It is consistent with scenarios of bar-induced evolution from later to earlier-type galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/516/A4
- Title:
- NGC1600, NGC4125, NGC7619 extended spectroscopy
- Short Name:
- J/A+A/516/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high quality long slit spectra along the major and minor axes out to 1.5-2R_e_ (14-22kpc) of three bright elliptical galaxies (NGC1600, NGC4125, NGC7619) obtained at the Hobby-Eberly Telescope (HET). We derive stellar kinematic profiles and Lick/IDS indices (H{beta}, Mgb, Fe_{5015}, Fe_{5270}, Fe_{5335}, Fe_{5406}). Moreover, for NGC4125 we derive gas kinematics and emission line strengths. We model the absorption line strengths using Simple Stellar Populations models that take into account the variation of {alpha}/Fe and derive ages, total metallicity and element abundances. Overall, we find that the three galaxies have old and {alpha}/Fe overabundant stellar populations with no significant gradients. The metallicity is supersolar at the center with a strong negative radial gradient. For NGC4125, several pieces of evidence point to a recent dissipational merger event. We calculate the broad band color profiles with the help of SSP models. All of the colors show sharp peaks at the center of the galaxies, mainly caused by the metallicity gradients, and agree well with the measured colors. Using the Schwarzschild's axisymmetric orbit superposition technique, we model the stellar kinematics to constrain the dark halos of the galaxies. We use the tight correlation between the Mgb strength and local escape velocity to set limits on their extent by testing different halo sizes. Logarithmic halos cut at 60kpc minimize the overall scatter of the Mgb-V_esc_ relation. Larger cutoff radii are found if the dark matter density profile is decreasing more steeply at large radii.
- ID:
- ivo://CDS.VizieR/J/ApJ/808/183
- Title:
- NGC1271 stellar kinematics
- Short Name:
- J/ApJ/808/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small effective radius of 2.2kpc and a large bulge stellar velocity dispersion of 276km/s for its K-band luminosity of 8.9x10^10^L_{sun}_. We present a mass measurement for the black hole in this compact, high-dispersion galaxy using observations from the Near-infrared Integral Field Spectrometer on the Gemini North telescope assisted by laser guide star adaptive optics, large-scale integral field unit observations with PPAK at the Calar Alto Observatory, and Hubble Space Telescope WFC3 imaging observations. We are able to map out the stellar kinematics both on small spatial scales, within the black hole sphere of influence, and on large scales that extend out to four times the galaxy's effective radius. We find that the galaxy is rapidly rotating and exhibits a sharp rise in the velocity dispersion. Through the use of orbit-based stellar dynamical models, we determine that the black hole has a mass of (3.0^+1.0^_-1.1_)x10^9^M_{sun}_ and the H-band stellar mass-to-light ratio is 1.40^+0.13^_-0.11_{gamma}_{sun}_ ({sigma} uncertainties). NGC 1271 occupies the sparsely populated upper end of the black hole mass distribution but is very different from the brightest cluster galaxies (BCGs) and giant elliptical galaxies that are expected to host the most massive black holes. Interestingly, the black hole mass is an order of magnitude larger than expectations based on the galaxy's bulge luminosity but is consistent with the mass predicted using the galaxy's bulge stellar velocity dispersion. More compact, high-dispersion galaxies need to be studied using high spatial resolution observations to securely determine black hole masses, as there could be systematic differences in the black hole scaling relations between these types of galaxies and the BCGs/giant ellipticals, thereby implying different pathways for black hole and galaxy growth.
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/3776
- Title:
- NGC 3115 Stellar Populations and Kinematics
- Short Name:
- J/MNRAS/487/3776
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a combination of the Schwarzschild orbit-superposition dynamical modelling technique with the spatially-resolved mean stellar age and metallicity maps to uncover the formation history of galaxies. We apply this new approach to a remarkable 5-pointing mosaic of VLT/MUSE observations obtained by Guerou et al. (2016A&A...591A.143G, Cat. J/A+A/591/A143) extending to a maximum galactocentric distance of ~120'' (5.6kpc) along the major axis, corresponding to ~2.5R_e. Our method first identifies 'families' of orbits from the dynamical model that represent dynamically distinct structures of the galaxy. Individual ages and metallicities of these components are then fit for using the stellar-population information. Our results highlight components of the galaxy that are distinct in the combined stellar dynamics/populations space, which implies distinct formation paths. We find evidence for a dynamically-cold, metal-rich disk, consistent with a gradual in-situ formation. This disk is embedded in a generally-old population of stars, with kinematics ranging from dispersion-dominated in the centre to an old, diffuse, metal-poor stellar halo at the extremities. We find also a direct correlation between the dominant dynamical support of these components, and their associated age, akin to the relation observed in the Milky Way. This approach not only provides a powerful model for inferring the formation history of external galaxies, but also paves the way to a complete population-dynamical model.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1558
- Title:
- NOAO Fundamental Plane Survey
- Short Name:
- J/AJ/128/1558
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce the NOAO Fundamental Plane Survey (NFPS), a wide-field imaging/spectroscopic study of rich, low-redshift galaxy clusters. The survey targets X-ray-selected clusters at 0.010<z<0.067, distributed over the whole sky, with imaging and spectroscopic observations obtained for 93 clusters. This data set will be used in investigations of galaxy properties in the cluster environment and of large-scale velocity fields through the fundamental plane. In this paper, we present details of the cluster sample construction and the strategies employed to select early-type galaxy samples for spectroscopy. Details of the spectroscopic observations are reported. From observations of 5479 red galaxies, we present redshift measurements for 5388 objects and internal velocity dispersions for 4131. The velocity dispersions have a median estimated error ~7%. The NFPS has ~15% overlap with previously published velocity dispersion data sets. Comparisons to these external catalogs are presented and indicate typical external errors of ~8%.
