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16811. Velocity dispersions for elliptical galaxies
ID:
ivo://CDS.VizieR/J/A+AS/113/151
Title:
Velocity dispersions for elliptical galaxies
Short Name:
J/A+AS/113/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
Measurements of central velocity dispersions and heliocentric radial velocities are presented for 94 field galaxies. Among these, 5 new radial velocities and 80 new central velocity dispersions are obtained. Reduction was performed independently by cross-correlation, Fourier-quotient and Fourier-correlation-quotient methods.
16812. Velocity dispersions in active galaxies
ID:
ivo://CDS.VizieR/J/ApJS/201/29
Title:
Velocity dispersions in active galaxies
Short Name:
J/ApJS/201/29
Date:
21 Oct 2021
Publisher:
CDS
Description:
We derive spatially resolved stellar kinematics for a sample of 84 out of 104 observed local (0.02<z<0.09) galaxies hosting type-1 active galactic nuclei (AGNs), based on long-slit spectra obtained at the 10m W. M. Keck-1 Telescope. In addition to providing central stellar velocity dispersions, we measure major axis rotation curves and velocity dispersion profiles using three separate wavelength regions, including the prominent Ca H&K, MgIb, and CaII NIR stellar features. In this paper, we compare kinematic measurements of stellar velocity dispersion obtained for different apertures, wavelength regions, and signal-to-noise ratios, and provide recipes to cross-calibrate the measurements reducing systematic effects to the level of a few percent. We also provide simple recipes based on readily observable quantities such as global colors and Ca H&K equivalent width that will allow observers of high-redshift AGN hosts to increase the probability of obtaining reliable stellar kinematic measurements from unresolved spectra in the region surrounding the Ca H&K lines.
16813. Velocity dispersions of MS1054-03 & Coma galaxies
ID:
ivo://CDS.VizieR/J/ApJ/724/714
Title:
Velocity dispersions of MS1054-03 & Coma galaxies
Short Name:
J/ApJ/724/714
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have measured velocity dispersions ({sigma}) for a sample of 36 galaxies with J<21.2 or M_r_<-20.6mag in MS 1054-03, a massive cluster of galaxies at z=0.83. Our data are of uniformly high quality down to our selection limit, our 16h exposures typically yielding errors of only {delta}({sigma})~10% for L* and fainter galaxies. By combining our measurements with data from the literature, we have 53 cluster galaxies with measured dispersions, and HST/ACS-derived sizes, colors and surface brightness. This sample is complete for the typical L^*^ galaxy at z~1, unlike most previous z~1 cluster samples which are complete only for the massive cluster members (>10^11^M_{sun}_). We find no evidence for a change in the tilt of the fundamental plane (FP).
16814. Velocity dispersions of 12 nearby galaxies
ID:
ivo://CDS.VizieR/J/AJ/146/150
Title:
Velocity dispersions of 12 nearby galaxies
Short Name:
J/AJ/146/150
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive study of the velocity dispersion of the atomic (HI) and molecular (H_2_) gas components in the disks (R{<~}R_25_) of a sample of 12 nearby spiral galaxies with moderate inclinations. Our analysis is based on sensitive high-resolution data from the THINGS (atomic gas) and HERACLES (molecular gas) surveys. To obtain reliable measurements of the velocity dispersion, we stack regions several kiloparsecs in size, after accounting for intrinsic velocity shifts due to galactic rotation and large-scale motions. We stack using various parameters: the galactocentric distance, star formation rate surface density, HI surface density, H_2_ surface density, and total gas surface density. We fit single Gaussian components to the stacked spectra and measure median velocity dispersions for HI of 11.9+/-3.1km/s and for CO of 12.0+/-3.9km/s. The CO velocity dispersions are thus, surprisingly, very similar to the corresponding ones of HI, with an average ratio of {sigma}_HI_/{sigma}_CO_=1.0+/-0.2 irrespective of the stacking parameter. The measured CO velocity dispersions are significantly higher (factor of ~2) than the traditional picture of a cold molecular gas disk associated with star formation. The high dispersion implies an additional thick molecular gas disk (possibly as thick as the HI disk). Our finding is in agreement with recent sensitive measurements in individual edge-on and face-on galaxies and points toward the general existence of a thick disk of molecular gas, in addition to the well-known thin disk in nearby spiral galaxies.
16815. Velocity distributions in galaxy clusters
ID:
ivo://CDS.VizieR/J/other/NewA/27.41
Title:
Velocity distributions in galaxy clusters
Short Name:
J/other/NewA/27.
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study 416 galaxy systems with more than 7 members selected from the 2MASS catalog. We applied five well known normality tests to the velocity distributions of these systems to distinguish Gaussian and non-Gaussian clusters. Using controlled samples, we estimated type I and II errors for each test. We verified that individual tests minimize the chances of classifying a Gaussian system as non-Gaussian, while the Fisher's meta-analysis method, a procedure to combine p-values from several statistical tests, minimizes the chances of classifying a non-Gaussian system as Gaussian. Taking the positive elements of each method and also including a modality analysis of the velocity distribution, we defined objective criteria to split up the sample into Gaussian and non-Gaussian clusters. Our analysis indicates that 50-58% of groups have Gaussian distribution, a lower fraction than that we found using individual normality tests, 71-87%. We also found that some properties of galaxy clusters are significantly different between Gaussian and non-Gaussian systems. For instance, non-Gaussian clusters have larger radii and contain more galaxies than Gaussian clusters. Finally, we discussed the importance of choosing the adequate methodology to classify galaxy systems from their velocity distributions and also the dependence of the results on the criteria used to identify clusters in galaxy surveys.
16816. Velocity field in the Local Group
ID:
ivo://CDS.VizieR/J/A+A/393/57
Title:
Velocity field in the Local Group
Short Name:
J/A+A/393/57
Date:
21 Oct 2021
Publisher:
CDS
Description:
Pratton, Melott and McKee (1997ApJ...479L..15P) showed that the velocity field around clusters could generate an apparent distortion that appears as tangential structures or radial filaments. In the present paper we determine the parameters of the Peebles' model (1976ApJ...205..318P) describing infall of galaxies onto clusters with the aim of testing quantitatively the amplitude of this distortion. The distances are determined from the concept of sosie galaxies (Paturel, 1994A&A...289..711P) using 21 calibrators for which the distances were recently calculated from two independent Cepheid calibrations. We use both B and I-band magnitudes.
16817. Velocity field of the Lyra complex
ID:
ivo://CDS.VizieR/J/A+A/633/A108
Title:
Velocity field of the Lyra complex
Short Name:
J/A+A/633/A108
Date:
02 Nov 2021 11:15:00
Publisher:
CDS
Description:
The formation of cosmic structures culminates with the assembly of galaxy clusters, a process that is quite different from cluster to cluster. We present the study of the structure and dynamics of the Lyra complex, consisting of the two clusters RXC J1825.3+3026 and CIZA J1824.1+3029, which was very recently studied by using both X-ray and radio data. This is the first analysis based on the kinematics of member galaxies. New spectroscopic data for 285 galaxies were acquired at the Italian Telescopio Nazionale Galileo and were used in combination with PanSTARRS photometry. The result of our member selection is a sample of 198 galaxies. For RXCJ1825 and CIZAJ1824 we report the redshifts, z=0.0645 and z=0.0708, the first estimates of velocity dispersion, sigma_v_=995_-125_^+131^km/s and sigma_v_=700+/-50km/s, and of dynamical mass, M_200_=1.1+/-0.4x10^15^M_[sun}_ and M_200_=4+/-0.110^14^M_{sun}_. The past assembly of RXCJ1825 is traced by the two dominant galaxies, which are both aligned with the major axis of the galaxy distribution along the east-west direction, and by a minor northeast substructure. We also detect a quite peculiar high velocity field in the southwest region of the Lyra complex. This feature is likely related to a very luminous galaxy, which is characterized by a high velocity. This galaxy is suggested to be the central galaxy of a group that is in interaction with RXCJ1825 according to very recent studies based on X-ray and radio data. The redshift of the whole Lyra complex is z=0.067. Assuming that the redshift difference between RXCJ1825 and CIZAJ1824 is due to the relative kinematics, the projected distance between the cluster centers is D~1.3Mpc and the line-of-sight velocity difference is ~1750km/s. A dynamical analysis of the system shows that the two clusters are likely to be gravitationally bound in a pre-merger phase, and that CIZAJ1824 is moving toward RXCJ1825. Our results corroborate a picture where the Lyra region is the place of a very complex scenario of cluster assembly.
16818. Velocity gradient and brightness in disc galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/433/L30
Title:
Velocity gradient and brightness in disc galaxies
Short Name:
J/MNRAS/433/L30
Date:
21 Oct 2021
Publisher:
CDS
Description:
For disc galaxies, a close relation exists between the distribution of light and the shape of the rotation curve. We quantify this relation by measuring the inner circular-velocity gradient d_R_V(0) for spiral and irregular galaxies with high-quality rotation curves. We find that d_R_V(0) correlates with the central surface brightness {mu}_0_ over more than two orders of magnitude in d_R_V(0) and four orders of magnitudes in {mu}_0_. This is a scaling relation for disc galaxies. It shows that the central stellar density of a galaxy closely relates to the inner shape of the potential well, also for low-luminosity and low-surface-brightness galaxies that are expected to be dominated by dark matter.
16819. Velocity measurements in Segue 1
ID:
ivo://CDS.VizieR/J/ApJ/733/46
Title:
Velocity measurements in Segue 1
Short Name:
J/ApJ/733/46
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a comprehensive Keck/DEIMOS spectroscopic survey of the ultra-faint Milky Way satellite galaxy Segue 1. We have obtained velocity measurements for 98.2% of the stars within 67pc (10', or 2.3 half-light radii) of the center of Segue 1 that have colors and magnitudes consistent with membership, down to a magnitude limit of r=21.7. Based on photometric, kinematic, and metallicity information, we identify 71 stars as probable Segue 1 members, including some as far out as 87pc. After correcting for the influence of binary stars using repeated velocity measurements, we determine a velocity dispersion of 3.7^+1.4^_-1.1_km/s. The mass within the half-light radius is 5.8^+8.2^_-3.1_x10^5^M_{sun}_. The stellar kinematics of Segue 1 require very high mass-to-light ratios unless the system is far from dynamical equilibrium, even if the period distribution of unresolved binary stars is skewed toward implausibly short periods. With a total luminosity less than that of a single bright red giant and a V-band mass-to-light ratio of 3400M_{sun}_/L_{sun}_, Segue 1 is the darkest galaxy currently known.
16820. Velocity of eight RASSCALS galaxy groups
ID:
ivo://CDS.VizieR/J/ApJ/622/187
Title:
Velocity of eight RASSCALS galaxy groups
Short Name:
J/ApJ/622/187
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the distribution of gas pressure and entropy in eight groups of galaxies belonging to the ROSAT All-Sky Survey/Center for Astrophysics Loose Systems (RASSCALS, Cat. <J/ApJ/534/114>). We use archival and proprietary XMM-Newton observations, supplementing the X-ray data with redshifts derived from the literature; we also list 125 new redshifts measured with the Gemini North telescope.

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