- ID:
- ivo://CDS.VizieR/J/A+AS/137/419
- Title:
- Dynamics of blue compact galaxies I. The data
- Short Name:
- J/A+AS/137/419
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of six luminous blue compact galaxies (BCGs) and two star forming companion galaxies were carried out with the CIGALE scanning Fabry-Perot interferometer attached to the ESO 3.6m telescope on La Silla. The observations were made in the H-alpha emission line which is prominent in BCGs. A velocity sampling of 5km/s and a pixel size of 0.9arcseconds were used. In this paper we present the observations and the data together with the velocity fields and the derived rotation curves. In addition we provide rough estimates of the total dynamical mass and of the ionised gas mass for each galaxy. All galaxies display rotation, but while the companion galaxies have regular velocity fields, those of the BCGs are complex and appear perturbed. This is the most extensive study to date of the optical velocity fields of BCGs. The interpretation of these results will be presented in a forthcoming paper (Paper II).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/139/483
- Title:
- Early-type gal. kinematics in compact groups
- Short Name:
- J/A+AS/139/483
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of stellar kinematics for seven early-type galaxies in HCG 67, HCG 74, and HCG 79. These data are aimed at studying the relation between the environment and the dynamics, structure and stellar content of early-type galaxies. In the present three groups, the kinematic features we observed cannot be associated unambiguously to physical interactions. Visible morphological peculiarities do not appear correlated with kinematical perturbations.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A123
- Title:
- Einasto parameters for SPARC galaxies
- Short Name:
- J/A+A/623/A123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dark matter-baryon scaling relations in galaxies are important in order to constrain galaxy formation models. Here, we provide a modern quantitative assessment of those relations, by modelling the rotation curves of galaxies from the Spitzer Photometry and Accurate Rotation Curves (SPARC) database with the Einasto dark halo model. We focus in particular on the comparison between the original SPARC parameters, with constant mass-to-light ratios for bulges and disks, and the parameters for which galaxies follow the tightest radial acceleration relation. We show that fits are improved in the second case, and that the pure halo scaling relations also become tighter. We report that the density at the radius where the slope is -2 is strongly anticorrelated to this radius, and to the Einasto index. The latter is close to unity for a large number of galaxies, indicative of large cores. In terms of dark matter-baryon scalings, we focus on relations between the core properties and the extent of the baryonic component, which are relevant to the cusp-core transformation process. We report a positive correlation between the core size of halos with small Einasto index and the stellar disk scale-length, as well as between the averaged dark matter density within 2kpc and the baryon-induced rotational velocity at that radius. This finding is related to the consequence of the radial acceleration relation on the diversity of rotation curve shapes, quantified by the rotational velocity at 2kpc. While a tight radial acceleration relation slightly decreases the observed diversity compared to the original SPARC parameters, the diversity of baryon-induced accelerations at 2kpc is sufficient to induce a large diversity, incompatible with current hydrodynamical simulations of galaxy formation, while maintaining a tight radial acceleration relation.
- ID:
- ivo://CDS.VizieR/J/ApJ/714/1170
- Title:
- Faraday rotation at high Galactic latitude
- Short Name:
- J/ApJ/714/1170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the vertical magnetic field of the Milky Way toward the Galactic poles, determined from observations of Faraday rotation toward more than 1000 polarized extragalactic radio sources at Galactic latitudes |b|>=77{deg}, using the Westerbork Radio Synthesis Telescope and the Australia Telescope Compact Array. We find median rotation measures (RMs) of 0.0+/-0.5rad/m^2^ and +6.3+/-0.7rad/m^2^ toward the north and south Galactic poles, respectively, demonstrating that there is no coherent vertical magnetic field in the Milky Way at the Sun's position. If this is a global property of the Milky Way's magnetism, then the lack of symmetry across the disk rules out pure dipole or quadrupole geometries for the Galactic magnetic field. The angular fluctuations in RM seen in our data show no preferred scale within the range ~0.1{deg} to ~25{deg}. The observed standard deviation in RM of ~9rad/m^2^ then implies an upper limit of ~1uG on the strength of the random magnetic field in the warm ionized medium at high Galactic latitudes.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/63
- Title:
- Faraday rotation from magnesium II absorbers
- Short Name:
- J/ApJ/795/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Strong singly ionized magnesium (Mg II) absorption lines in quasar spectra typically serve as a proxy for intervening galaxies along the line of sight. Previous studies have found a correlation between the number of these Mg II absorbers and the Faraday rotation measure (RM) at ~5 GHz. We cross-match a sample of 35752 optically identified non-intrinsic Mg II absorption systems with 25649 polarized background radio sources for which we have measurements of both the spectral index and RM at 1.4 GHz. We use the spectral index to split the resulting sample of 599 sources into flat-spectrum and steep-spectrum subsamples. We find that our flat-spectrum sample shows significant (~3.5{sigma}) evidence for a correlation between Mg II absorption and RM at 1.4 GHz, while our steep-spectrum sample shows no such correlation. We argue that such an effect cannot be explained by either luminosity or other observational effects, by evolution in another confounding variable, by wavelength-dependent polarization structure in an active galactic nucleus, by the Galactic foreground, by cosmological expansion, or by partial coverage models. We conclude that our data are most consistent with intervenors directly contributing to the Faraday rotation along the line of sight, and that the intervening systems must therefore have coherent magnetic fields of substantial strength (B{bar}=1.8+/-0.4{mu}G). Nevertheless, the weak nature of the correlation will require future high-resolution and broadband radio observations in order to place it on a much firmer statistical footing.
- ID:
- ivo://CDS.VizieR/J/PAZh/37/281
- Title:
- Galactic rotation curve from selected maser
- Short Name:
- J/PAZh/37/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on currently available observations of 28 maser sources in 25 star-forming regions with measured trigonometric parallaxes, proper motions, and radial velocities, we have constructed the rotation curve of the Galaxy. Taking different distances to the Galactic center R_0_, we have estimated the peculiar velocity of the Sun, the angular velocity of Galactic rotation, and its three derivatives.
- ID:
- ivo://CDS.VizieR/VII/70A
- Title:
- Galaxies Rotation Curves
- Short Name:
- VII/70A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains all bibliographical information pertaining to rotation curves of external galaxies that have appeared in the astronomical literature up to 1981 December. Information about 271 galaxies is given from 332 papers. The catalog includes galaxy names, morphological types, positions, radial velocities, approximate extent of the rotation curves from the centers of the galaxies, and references.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/2616
- Title:
- Galaxy cluster's rotation
- Short Name:
- J/MNRAS/465/2616
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the possible rotation of cluster galaxies, developing, testing, and applying a novel algorithm which identifies rotation, if such does exist, as well as its rotational centre, its axis orientation, rotational velocity amplitude, and, finally, the clockwise or counterclockwise direction of rotation on the plane of the sky. To validate our algorithms we construct realistic Monte Carlo mock rotating clusters and confirm that our method provides robust indications of rotation. We then apply our methodology on a sample of Abell clusters with z<=0.1 with member galaxies selected from the Sloan Digital Sky Survey DR10 spectroscopic data base. After excluding a number of substructured clusters, which could provide erroneous indications of rotation, and taking into account the expected fraction of misidentified coherent substructure velocities for rotation, provided by our Monte Carlo simulation analysis, we find that ~23 per cent of our clusters are rotating under a set of strict criteria. Loosening the strictness of the criteria, on the expense of introducing spurious rotation indications, we find this fraction increasing to ~28 per cent. We correlate our rotation indicators with the cluster dynamical state, provided either by their Bautz-Morgan type or by their X-ray isophotal shape and find for those clusters showing rotation within 1.5h^-1^_70_ Mpc that the significance of their rotation is related to the dynamically younger phases of cluster formation but after the initial anisotropic accretion and merging has been completed. Finally, finding rotational modes in galaxy clusters could lead to the necessity of correcting the dynamical cluster mass calculations.
- ID:
- ivo://CDS.VizieR/J/ApJ/636/721
- Title:
- Galaxy rotation curves
- Short Name:
- J/ApJ/636/721
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We apply the modified acceleration law obtained from Einstein gravity coupled to a massive skew-symmetric field F_{mu}{nu}{lambda}_ to the problem of explaining galaxy rotation curves without exotic dark matter. Our sample of galaxies includes low surface brightness (LSB) and high surface brightness (HSB) galaxies and an elliptical galaxy. In those cases for which photometric data are available, a best fit via the single parameter (M/L)_stars_ to the luminosity of the gaseous (HI plus He) and luminous stellar disks is obtained. In addition, a best fit to the rotation curves of galaxies is obtained in terms of a parametric mass distribution (independent of luminosity observations) - a two-parameter fit to the total galactic mass (or mass-to-light ratio M/L) and a core radius associated with a model of the galaxy cores - using a nonlinear least-squares fitting routine including estimated errors. The fits are compared to those obtained using Milgrom's phenomenological MOND model and to the predictions of the Newtonian/Kepler acceleration law.
- ID:
- ivo://CDS.VizieR/J/A+A/374/394
- Title:
- Gas and stars kinematics in disc galaxies
- Short Name:
- J/A+A/374/394
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ionized gas and stellar kinematical parameters have been measured along the major axis of 20 nearby disc galaxies. We discuss the properties of each sample galaxy, distinguishing between those characterized by regular or peculiar kinematics. In early-type disc galaxies, ionized gas tends to rotate faster than stars and to have a lower velocity dispersion (V_g_>V_*_ and {sigma}_g_<{sigma}_*_), whereas in late-type spirals, gas and stars show almost the same rotation velocities and velocity dispersions (V_g_=~V_*_ and {sigma}_g_=~{sigma}_*_). Incorporating the early-type disc galaxies studied by Bertola et al. (1995ApJ...448L..13B), Fisher (1997, Cat. <J/AJ/113/950>) and Corsini et al. (1999, Cat. <J/A+A/342/671>), we have compiled a sample of some 40 galaxies for which the major-axis radial profiles of both the stellar and gaseous components have been measured. The value of {sigma}_*_ measured at R_e_/4 turns out to be strongly correlated with the galaxy morphological type, while {sigma}_g_ is not and sometimes takes values above the range expected from thermal motions or small-scale turbulence.
