- ID:
- ivo://CDS.VizieR/J/MNRAS/442/3329
- Title:
- Rotation measures of 2642 quasars
- Short Name:
- J/MNRAS/442/3329
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained the rotation measures (RMs) of 2642 quasars by using cross-identification of the most updated quasar catalogue and the RM catalogue. After discounting the foreground Galactic Faraday rotation of the Milky Way, we obtain the residual rotation measure (RRM) of these quasars. We have carefully discarded the effects from measurement and systematical uncertainties of RRMs as well as large RRMs from RM outliers, and we have obtained marginal evidence for the redshift evolution of the real dispersion of RRMs which steadily increases to 10rad/m^2^ about z~1 and is saturated at higher redshifts. Ionized clouds in the form of galaxy halos, galaxy clusters or cosmological filaments with different RM dispersion widths could produce the observed RRM evolutions. However, current data sets cannot constrain the contributions from galaxy halos and cosmic webs. Future measurements of RMs for a large sample of quasars with high precision are necessary to disentangle these different contributions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/596/A84
- Title:
- S4G disk galaxies stellar mass distribution
- Short Name:
- J/A+A/596/A84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Models of galaxy formation in a cosmological framework require observational constraints to be tested against, such as the average stellar density profiles (and their dispersion) as a function of fundamental galaxy properties (e.g. the total stellar mass). Simulation models predict that the torques produced by stellar bars efficiently redistribute the stellar and gaseous material inside the disk, pushing it outwards or inwards depending on whether it is beyond or inside the bar corotation resonance radius, respectively. Bars themselves are expected to evolve, getting longer and narrower as they trap particles from the disk and slow down their rotation speed. We use 3.6um photometry from the Spitzer Survey of Stellar Structure in Galaxies (S4G) to trace the stellar distribution in nearby disk galaxies (z~~0) with total stellar masses 10^8.5^<=M*/M_{sun}_<=10^11^ and mid IR Hubble types -3<=T<=10. We characterize the stellar density profiles ({SIGMA}*), the stellar contribution to the rotation curves (V3.6um) and the m=2 Fourier amplitudes (A2) as a function of M* and T. We also describe the typical shapes and strengths of stellar bars in the S4G sample and link their properties to the total stellar mass and morphology of their host galaxy. For 1154 S4G galaxies with disk inclinations lower than 65{deg}, we perform a Fourier decomposition and rescale their images to a common frame determined by the size in physical units, by their disk scalelength, and for 748 barred galaxies by both the length and orientation of their bars. We stack the resized density profiles and images to obtain statistically representative average stellar disks and bars in bins of M* and T. Based on the radial force profiles of individual galaxies we calculate the mean stellar contribution to the circular velocity. We also calculate average A2 profiles, where the radius is normalized to R25.5. Furthermore, we infer the gravitational potentials from the synthetic bars to obtain the tangential-to-radial force ratio (QT) and A2 profiles in the different bins. We also apply ellipse fitting to quantitatively characterize the shape of the bar stacks. For M*>=10^9^M_{sun}_, we find a significant difference in the stellar density profiles of barred and non-barred systems: (i) disks in barred galaxies show larger scalelengths (hR) and fainter extrapolated central surface brightnesses ({SIGMA}0), (ii) the mean surface brightness profiles ({SIGMA}*) of barred and non-barred galaxies intersect each other slightly beyond the mean bar length, most likely at the bar corotation, and (iii) the central mass concentration of barred galaxies is larger (by almost a factor 2 when T<=5) than in their non-barred counterparts. The averaged {SIGMA}* profiles follow an exponential slope down to at least ~10M_{sun}_/pc^2^, which is the typical depth beyond which the sample coverage in the radial direction starts to drop. Central mass concentrations in massive systems (>=10^10^M_{sun}_) are substantially larger than in fainter galaxies, and their prominence scales with T. This segregation also manifests in the inner slope of the mean stellar component of the circular velocity: lenticular (S0) galaxies present the most sharply rising V3.6um . Based on the analysis of bar stacks, we show that early- and intermediate-type spirals (0<=T<5) have intrinsically narrower bars compared to later types and S0s, whose bars are oval-shaped. We show a clear agreement between galaxy family and quantitative estimates of bar strength. In early- and intermediate-type spirals, A2 is larger within and beyond the typical bar region among barred galaxies, compared to the non-barred subsample. Strongly barred systems also tend to have larger A2 amplitudes at all radii than their weakly barred counterparts. Using near-IR wavelengths (S4G 3.6um), we provide observational constraints for galaxy formation models to be checked against. In particular, we calculate the mean stellar density profiles, and the disk(+bulge) component of the rotation curve (and their dispersion) in bins of M* and T. We find evidence for bar-induced secular evolution of disk galaxies, in terms of disk spreading and enhanced central mass concentration. We also obtain average bars (2-D), and we show that bars hosted by early-type galaxies are more centrally concentrated and have larger density amplitudes than their late-type counterparts.
- ID:
- ivo://CDS.VizieR/J/MNRAS/387/1099
- Title:
- Spectroscopic study of 10 high SB galaxies
- Short Name:
- J/MNRAS/387/1099
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry and long-slit spectroscopy are presented for a sample of six galaxies with a low surface-brightness stellar disc and a bulge. The characterizing parameters of the bulge and disc components were derived by means of a two-dimensional photometric decomposition of the images of the sample galaxies. Their surface-brightness distribution was assumed to be the sum of the contribution of a Sersic bulge and an exponential disc, with each component being described by elliptical and concentric isophotes of constant ellipticity and position angle. The stellar and ionized-gas kinematics were measured along the major and minor axes in half of the sample galaxies, whereas the other half was observed only along two diagonal axes. Spectra along two diagonal axes were obtained also for one of the objects with major and minor axis spectra. The kinematic measurements extend in the disc region out to a surface-brightness level mu_R_~24mag/arcsec^2^, reaching in all cases the flat part of the rotation curve. The stellar kinematics turns out to be more regular and symmetric than the ionized-gas kinematics, which often shows the presence of non-circular, off-plane and non-ordered motions. This raises the question about the reliability of the use of the ionized gas as the tracer of the circular velocity in the modelling of the mass distribution, in particular in the central regions of low surface-brightness galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/146/45
- Title:
- Spectroscopy of 6 early-type galaxies
- Short Name:
- J/AJ/146/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Adaptive optics assisted SINFONI observations of the central regions of 10 early-type galaxies are presented. Based primarily on the SINFONI kinematics, 10 black hole (BH) masses occupying the high-mass regime of the M_BH_-{sigma} relation are derived using three-integral Schwarzschild models. The effect of dark matter (DM) inclusion on the BH mass is explored. The omission of a DM halo in the model results in a higher stellar mass-to-light ratio, especially when extensive kinematic data are used in the model. However, when the diameter of the sphere of influence--computed using the BH mass derived without a dark halo--is at least 10 times the point-spread function FWHM during the observations, it is safe to exclude a DM component in the dynamical modeling, i.e., the change in BH mass is negligible. When the spatial resolution is marginal, restricting the mass-to-light ratio to the right value returns the correct M_BH_ although a dark halo is not present in the model. Compared to the M_BH_-{sigma} and M_BH_-L relations of McConnell et al., the 10 BHs are all more massive than expected from the luminosities and 7 BH masses are higher than expected from the stellar velocity dispersions of the host bulges. Using new fitted relations, which include the 10 galaxies, we find that the space density of the most massive BHs (M_BH_>~10^9^M_{sun}_) estimated from the M_BH_-L relation is higher than the estimate based on the M_BH_-{sigma} relation and the latter is higher than model predictions based on quasar counts, each by about an order of magnitude.
- ID:
- ivo://CDS.VizieR/J/ApJS/106/27
- Title:
- Spiral galaxies in pairs
- Short Name:
- J/ApJS/106/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation curves have been obtained for 76 spiral galaxies in pairs, including a geometrically selected subset from the Karachentsev catalog and a set of Seyfert galaxies with close companions. Derived parameters of the rotation curves and the galaxies' light distributions are also presented. The rotation curves are classified broadly by shape, with special emphasis on kinematic disturbances and regions of solid-body behavior that may lead to bar development. Broadband images of the galaxies allow assessments of their degree of symmetry or disturbance. These velocity slices afford an empirical basis for evaluating the accuracy of radial velocity measures for spiral galaxies in pairs, and the dynamically important radial velocity differences. Specifically, the disagreement among several plausible ways of estimating the central velocity from these rotation data is used to estimate how closely any of these might approximate the nuclear or center-of-mass values. From seven indicators of central velocity, the internal scatter is delta_vv = 34 km/s. Of these, the velocity weighted by Halpha intensity along the slit shows a systematic offset of about 20 km/s with respect to the others for the Karachentsev pairs, in the sense that this measure is redshifted with respect to the other indicators. This is in the sense (but not of the total magnitude) required to account for statistical asymmetries in pair velocity differences. Individual scatter between the velocity indicators taken pairwise ranges from delta = 20 to 52 km/s. These results imply that emission-line data such as these cannot specify the center of mass or nuclear redshift at a level more accurate than this, even for arbitrarily precise velocity measurements, because it is not clear how the observed quantities relate to the desired measurement in a physical sense. No useful predictor of which galaxies have large or small scatter among velocity measures was found, except that the scatter is small for the class of "nonrotating" galaxies with small overall velocity amplitudes. Projected separation, separation normalized to disk scale length, and morphological disturbance do not correlate with velocity scatter.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1037
- Title:
- Spiral galaxies rotation curve data
- Short Name:
- J/AJ/130/1037
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new long-slit H{alpha} spectroscopy for 403 non-interacting spiral galaxies, obtained at the Palomar Observatory 5m Hale telescope, which is used to derive well-sampled optical rotation curves. Because many of the galaxies show optical emission features that are significantly extended along the spectrograph slit, a technique was devised to separate and subtract the night sky lines from the galaxy emission. We exploit a functional fit to the rotation curve to identify its center of symmetry; this method minimizes the asymmetry in the final, folded rotation curve. We derive rotational widths using both velocity histograms and the Polyex model fit. The final rotational width is measured at a radius containing 83% of the total light as derived from I-band images.
- ID:
- ivo://CDS.VizieR/J/ApJS/99/501
- Title:
- Spiral galaxies rotation curves
- Short Name:
- J/ApJS/99/501
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the rotation curves of 967 southern spiral galaxies, obtained by deprojecting and folding the raw H{alpha} data originally published by Mathewson, Ford, & Buchhorn (1992ApJS...81..413M). For 900 objects, we also present, in figures and tables, the rotation curves smoothed on scales corresponding to 5%-20% of the optical size; of these, 80 meet objective excellence criteria and are suitable for individual detailed mass modeling, while 820, individually less compelling mainly because of the moderate statistics and/or limited extension, are suitable for statistical studies. The remaining 67 curves suffer from severe asymmetries, small statistics, and large internal scatter that may largely limit their use in galaxy structure studies. The deprojected folded curves, the smoothed curves, and various related quantities are available via anonymous ftp at galileo.sissa.it in the directory /users/ftp/pub/psrot.
- ID:
- ivo://CDS.VizieR/J/ApJS/127/39
- Title:
- Stellar and gas kinematics in early-type galaxies
- Short Name:
- J/ApJS/127/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present data on stellar and gaseous kinematics of 14 gas-rich early-type galaxies. File galaxies.dat contains the list of observed galaxies, with coordinates, distance, absolute magnitude, and position angles. File stellar.dat contains stellar rotation curves and velocity dispersion profiles. File gaseous.dat contains the gaseous velocity profiles.
- ID:
- ivo://CDS.VizieR/J/A+A/360/439
- Title:
- Stellar and ionized gas kinematics in NGC 4672
- Short Name:
- J/A+A/360/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the case of the early-type disk galaxy NGC 4672 as a new example of a galaxy characterized by the orthogonal geometrical decoupling between bulge and disk. The morphological features of this galaxy are discussed as well as the velocity curves and velocity dispersion profiles of stars and ionized gas along both its major and minor axis. We conclude that NGC 4672 has structural (i.e. a bulge elongated perpendicularly to the disk) and kinematical (i.e. a stellar core rotating perpendicularly to the disk) properties similar to those of the Sa NGC 4698. The presence of the isolated core suggests that the disk component is the end result of the acquisition of external material in polar orbits around a pre-existing oblate spheroid as in the case of the ring component of AM 2020-504, the prototype of polar ring ellipticals.
- ID:
- ivo://CDS.VizieR/J/A+A/382/488
- Title:
- Stellar and ionized gas kinematics in NGC 2855
- Short Name:
- J/A+A/382/488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present major and minor-axis kinematics of stars and ionized gas as well as narrow and broad-band surface photometry of the Sa spiral NGC 2855. In the nuclear regions of this unbarred and apparently undisturbed spiral galaxy the gas is rotating perpendicularly to the galaxy disk. We suggest that this kinematically-decoupled component is the signature of an acquisition process in the history of this galaxy.
