- ID:
- ivo://CDS.VizieR/J/MNRAS/445/1412
- Title:
- HII regions and GMC in the Antennae
- Short Name:
- J/MNRAS/445/1412
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have combined observations of the Antennae galaxies from the radio interferometer ALMA (Atacama Large Millimeter/submillimeter Array) and from the optical interferometer GH{alpha}FaS (Galaxy H{alpha} Fabry-Perot System). The two sets of observations have comparable angular and spectral resolutions, enabling us to identify 142 giant molecular clouds (GMCs) and 303 HII regions. We have measured, and compared, their basic physical properties (radius, velocity dispersion, luminosity).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/611/A38
- Title:
- Hints for a bar in M31 kinematics and morphology
- Short Name:
- J/A+A/611/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As the nearest large spiral galaxy, M 31 provides a unique opportunity to study the structure and evolutionary history of this galaxy type in great detail. Among the many observing programs aimed at M 31 are microlensing studies, which require good three-dimensional models of the stellar mass distribution. Possible non-axisymmetric structures like a bar need to be taken into account. Due to M 31's high inclination, the bar is difficult to detect in photometry alone. Therefore, detailed kinematic measurements are needed to constrain the possible existence and position of a bar in M 31. We obtained ~=220 separate fields with the optical integral-field unit spectrograph VIRUS-W, covering the whole bulge region of M 31 and parts of the disk. We derived stellar line-of-sight velocity distributions from the stellar absorption lines, as well as velocity distributions and line fluxes of the emission lines H{beta}, [OIII] and [NI]. Our data supersede any previous study in terms of spatial coverage and spectral resolution. We find several features that are indicative of a bar in the kinematics of the stars, we see intermediate plateaus in the velocity and the velocity dispersion, and correlation between the higher moment h3 and the velocity. The gas kinematics is highly irregular, but is consistent with non-triaxial streaming motions caused by a bar. The morphology of the gas shows a spiral pattern, with seemingly lower inclination than the stellar disk. We also look at the ionization mechanisms of the gas, which happens mostly through shocks and not through starbursts.
- ID:
- ivo://CDS.VizieR/J/ApJS/240/15
- Title:
- HST/COS UV obs. of low-z SDSS galaxy groups
- Short Name:
- J/ApJS/240/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A small survey of the UV-absorbing gas in 12 low-z galaxy groups has been conducted using the Cosmic Origins Spectrograph on board the Hubble Space Telescope. Targets were selected from a large, homogeneously selected sample of groups found in the Sloan Digital Sky Survey. A critical selection criterion excluded sight lines that pass close (<1.5 virial radii) to a group galaxy, to ensure absorber association with the group as a whole. Deeper galaxy redshift observations are used both to search for closer galaxies and also to characterize these 10^13.5^-10^14.5^M_{sun}_ groups, the most massive of which are highly virialized with numerous early-type galaxies (ETGs). This sample also includes two spiral-rich groups, not yet fully virialized. At group-centric impact parameters of 0.3-2Mpc, these signal-to-noise ratios = 15-30 spectra detected HI absorption in 7 of 12 groups; high (OVI) and low (SiIII) ion metal lines are present in two-thirds of the absorption components. None of the three most highly virialized, ETG-dominated groups are detected in absorption. Covering fractions >~50% are seen at all impact parameters probed, but do not require large filling factors despite an enormous extent. Unlike halo clouds in individual galaxies, group absorbers have radial velocities that are too low to escape the group potential well without doubt. This suggests that these groups are "closed boxes" for galactic evolution in the current epoch. Evidence is presented that the cool and warm group absorbers are not a pervasive intra-group medium (IGrM), requiring a hotter (T~10^6^-10^7^K) IGrM to be present to close the baryon accounting.
- ID:
- ivo://CDS.VizieR/J/ApJ/881/42
- Title:
- HST phot. & GMOS spectra of Lynx E & W clusters
- Short Name:
- J/ApJ/881/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Few detailed investigations of stellar populations in passive galaxies beyond z~1 are based on deep spectroscopic observations, due to the difficulty in obtaining such data. We present a study of stellar populations, structure, and mass-to-light ratios (M/L) of a large sample of bulge-dominated galaxies in the two z=1.27 clusters Lynx E and Lynx W, based on deep ground-based optical spectroscopy combined with imaging from the Hubble Space Telescope. We find that Lynx E has a well-defined core of red passive galaxies, while Lynx W lacks such a core. If all the sample galaxies evolve similarly in size from z=1.27 to the present, the data would allow only 0.1dex size growth at a fixed dynamical mass. However, to link the Lynx central galaxies to brightest cluster galaxies similar to those of low-redshift clusters, the Lynx galaxies would have to grow by at least a factor 5, possibly through major merging. The M/L ratios and the Balmer absorption lines of the Lynx galaxies are consistent with passive evolution of the stellar populations from z=1.27 to the present and support ages of 1-3Gyr. The galaxies in the outskirts of the clusters contain younger stellar populations than found in the cluster cores. However, when evolved passively to z~0 both populations are consistent with the observed populations in the Coma cluster galaxies. The bulge-dominated emission line galaxies in the clusters are dominated by stellar populations with subsolar metallicities. Thus, additional enrichment of these is required to produce Coma-like stellar populations by z~0.
- ID:
- ivo://CDS.VizieR/J/ApJ/803/29
- Title:
- HSTPROMO catalogs. II. Kinematic profiles
- Short Name:
- J/ApJ/803/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present kinematical analyses of 22 Galactic globular clusters using the Hubble Space Telescope proper motion catalogs recently presented in Bellini et al. (Paper I, 2014ApJ...797..115B). For most clusters, this is the first proper-motion study ever performed, and, for many, this is the most detailed kinematic study of any kind. We use cleaned samples of bright stars to determine binned velocity-dispersion and velocity-anisotropy radial profiles and two-dimensional velocity-dispersion spatial maps. Using these profiles, we search for correlations between cluster kinematics and structural properties. The profiles and maps presented here can provide a basis for detailed dynamical modeling of individual globular clusters. Given the quality of the data, this is likely to provide new insights into a range of topics concerning globular cluster mass profiles, structure, and dynamics.
- ID:
- ivo://CDS.VizieR/J/ApJ/827/12
- Title:
- HSTPROMO catalogs of GCs. IV. Blue straggler stars
- Short Name:
- J/ApJ/827/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We make use of the Hubble Space Telescope proper-motion catalogs derived by Bellini et al. (Paper I, 2014, J/ApJ/797/115) to produce the first radial velocity dispersion profiles {sigma}(R) for blue straggler stars (BSSs) in Galactic globular clusters (GCs), as well as the first dynamical estimates for the average mass of the entire BSS population. We show that BSSs typically have lower velocity dispersions than stars with mass equal to the main-sequence turnoff mass, as one would expect for a more massive population of stars. Since GCs are expected to experience some degree of energy equipartition, we use the relation {sigma}{propto}M^-{eta}^, where {eta} is related to the degree of energy equipartition, along with our velocity dispersion profiles to estimate BSS masses. We estimate {eta} as a function of cluster relaxation from recent Monte Carlo cluster simulations by Bianchini+ (2016MNRAS.458.3644B) and then derive an average mass ratio M_BSS_/M_MSTO_=1.50+/-0.14 and an average mass M_BSS_=1.22+/-0.12M_{sun}_ from 598 BSSs across 19 GCs. The final error bars include any systematic errors that are random between different clusters, but not any potential biases inherent to our methodology. Our results are in good agreement with the average mass of M_BSS_=1.22+/-0.06M_{sun}_ for the 35 BSSs in Galactic GCs in the literature with properties that have allowed individual mass determination.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/149
- Title:
- HSTPROMO. III. Dynamical distances
- Short Name:
- J/ApJ/812/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present dynamical distance estimates for 15 Galactic globular clusters (GCs) and use these to check the consistency of dynamical and photometric distance estimates. For most of the clusters, this is the first dynamical distance estimate ever determined. We extract proper-motion (PM) dispersion profiles using cleaned samples of bright stars from the Hubble Space Telescope PM catalogs recently presented in Bellini et al. (Paper I, 2014, J/ApJ/797/115) and compile a set of line of sight (LOS) velocity-dispersion profiles from a variety of literature sources. Distances are then estimated by fitting spherical, non-rotating, isotropic, constant mass-to-light ratio (M/L) dynamical models to the PM and LOS dispersion profiles together. We compare our dynamical distance estimates with literature photometric estimates from the Harris GC catalog (VII/202) and find that the mean fractional difference between the two types is consistent with zero at just -1.9+/-1.7%. This indicates that there are no significant biases in either estimation method and provides an important validation of the stellar-evolution theory that underlies photometric distance estimates. The analysis also estimates dynamical M/Ls for our clusters; on average, the dynamically inferred M/Ls agree with existing stellar-population-based M/Ls that assume a Chabrier initial mass function (IMF) to within -8.8+/-6.4%, implying that such an IMF is consistent with our data. Our results are also consistent with a Kroupa IMF, but strongly rule out a Salpeter IMF. We detect no correlation between our M/L offsets from literature values and our distance offsets from literature values, strongly indicating that our methods are reliable and our results are robust.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/117
- Title:
- HyperLeda sample of nearby elliptical galaxies
- Short Name:
- J/ApJ/756/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the effect of the environment on the Faber-Jackson (FJ) relation, using a sample of 384 nearby elliptical galaxies and estimating objectively their environment on the typical scale of galaxy clusters. We show that the intrinsic scatter of the FJ relation is significantly reduced when ellipticals in high-density environments are compared to ellipticals in low-density ones. This result, which holds in a limited range of overdensities, is likely to provide an important observational link between scaling relations and formation mechanisms in galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/148/117
- Title:
- Imaging and spectroscopy in Lynx W
- Short Name:
- J/AJ/148/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- RX J0848.6+4453 (Lynx W) at redshift 1.27 is part of the Lynx Supercluster of galaxies. We present an analysis of the stellar populations and star formation history for a sample of 24 members of the cluster. Our study is based on deep optical spectroscopy obtained with Gemini North combined with imaging data from Hubble Space Telescope. Focusing on the 13 bulge-dominated galaxies for which we can determine central velocity dispersions, we find that these show a smaller evolution with redshift of sizes and velocity dispersions than reported for field galaxies and galaxies in poorer clusters. Our data show that the galaxies in RX J0848.6+4453 populate the fundamental plane (FP) similar to that found for lower-redshift clusters. The zero-point offset for the FP is smaller than expected if the cluster's galaxies are to evolve passively through the location of the FP we established in our previous work for z=0.8-0.9 cluster galaxies and then to the present-day FP. The FP zero point for RXJ0848.6+4453 corresponds to an epoch of last star formation at z_form_=1.95_-0.15_^+0.22^. Further, we find that the spectra of the galaxies in RXJ0848.6+4453 are dominated by young stellar populations at all galaxy masses and in many cases show emission indicating low-level ongoing star formation. The average age of the young stellar populations as estimated from the strength of the high-order Balmer line H{zeta} is consistent with a major star formation episode 1-2Gyr prior, which in turn agrees with z_form_=1.95. These galaxies dominated by young stellar populations are distributed throughout the cluster. We speculate that low-level star formation has not yet been fully quenched in the center of this cluster, possibly because the cluster is significantly poorer than other clusters previously studied at similar redshifts, which appear to have very little ongoing star formation in their centers. The mixture in RXJ0848.6+4453 of passive galaxies with young stellar populations and massive galaxies still experiencing some star formation appears similar to the galaxy populations recently identified in two z{approx}2 clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/145/77
- Title:
- Imaging and spectroscopy in three galaxy clusters
- Short Name:
- J/AJ/145/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of stellar populations and evolutionary history of galaxies in three similarly rich galaxy clusters MS0451.6-0305 (z=0.54), RXJ0152.7-1357 (z=0.83), and RXJ1226.9+3332 (z=0.89). Our analysis is based on high signal-to-noise ground-based optical spectroscopy and Hubble Space Telescope imaging for a total of 17-34 members in each cluster. Using the dynamical masses together with the effective radii and the velocity dispersions, we find no indication of evolution of sizes or velocity dispersions with redshift at a given galaxy mass. We establish the Fundamental Plane (FP) and scaling relations between absorption line indices and velocity dispersions. We confirm that the FP is steeper at z~0.86 compared to the low-redshift FP, indicating that under the assumption of passive evolution the formation redshift, z_form_, depends on the galaxy velocity dispersion (or alternatively mass). At a velocity dispersion of {sigma}=125km/s (Mass=10^10.55^M_{sun}_) we find z_form_=1.24+/-0.05, while at {sigma}=225km/s (Mass=10^11.36^M_{sun}_) the formation redshift is z_form_=1.95^+0.3^_-0.2_, for a Salpeter initial mass function. The three clusters follow similar scaling relations between absorption line indices and velocity dispersions as those found for low-redshift galaxies. The zero point offsets for the Balmer lines depend on cluster redshifts. However, the offsets indicate a slower evolution, and therefore higher formation redshift, than the zero point differences found from the FP, if interpreting the data using a passive evolution model. Specifically, the strength of the higher order Balmer lines H{delta} and H{gamma} implies z_form_>2.8. The scaling relations for the metal indices in general show small and in some cases insignificant zero point offsets, favoring high formation redshifts for a passive evolution model.
