scholarly journals Sloshing in its cD halo: MUSE kinematics of the central galaxy NGC 3311 in the Hydra I cluster

2018 ◽  
Vol 609 ◽  
pp. A78 ◽  
Author(s):  
C. E. Barbosa ◽  
M. Arnaboldi ◽  
L. Coccato ◽  
O. Gerhard ◽  
C. Mendes de Oliveira ◽  
...  
Keyword(s):  
Velocity Dispersion ◽  
Mixture Distribution ◽  
Major Axis ◽  
Finite Mixture ◽  
Cluster Core ◽  
Cluster Center ◽  
Line Of Sight ◽  
Mean Velocity ◽  
Central Galaxy ◽  
Small Constant

Context. Early-type galaxies (ETGs) show a strong size evolution with redshift. This evolution is explained by fast “in-situ” star formation at high-z followed by a late mass assembly mostly driven by minor mergers that deposit stars primarily in the outer halo. Aims. We aim to identify the main structural components of the Hydra I cD galaxy NGC 3311 to investigate the connection between the central galaxy and the surrounding stellar halo. Methods. We produce maps of the line-of-sight velocity distribution (LOSVD) moments from a mosaic of MUSE pointings covering NGC 3311 out to 25 kpc. Combining deep photometric and spectroscopic data, we model the LOSVD maps using a finite mixture distribution, including four non-concentric components that are nearly isothermal spheroids, with different line-of-sight systemic velocities V, velocity dispersions σ, and small (constant) values of the higher order Gauss-Hermite moments h3 and h4. Results. The kinemetry analysis indicates that NGC 3311 is classified as a slow rotator, although the galaxy shows a line-of-sight velocity gradient along the photometric major axis. The comparison of the correlations between h3 and h4 with V/σ with simulated galaxies indicates that NGC 3311 assembled mainly through dry mergers. The σ profile rises to ≃ 400 km s-1 at 20 kpc, a significant fraction (0.55) of the Hydra I cluster velocity dispersion, indicating that stars there were stripped from progenitors orbiting in the cluster core. The finite mixture distribution modeling supports three inner components related to the central galaxy and a fourth component with large effective radius (51 kpc) and velocity dispersion (327 km s-1) consistent with a cD envelope. We find that the cD envelope is offset from the center of NGC 3311 both spatially (8.6 kpc) and in velocity (ΔV = 204 km s-1), but coincides with the cluster core X-ray isophotes and the mean velocity of core galaxies. Also, the envelope contributes to the broad wings of the LOSVD measured by large h4 values within 10 kpc. Conclusions. The cD envelope of NGC 3311 is dynamically associated with the cluster core, which in Hydra I is in addition displaced from the cluster center, presumably due to a recent subcluster merger.

scholarly journals Resolved Gas Kinematics in a Sample of Low-Redshift High Star-Formation Rate Galaxies

2016 ◽  
Vol 33 ◽  
Author(s):  
Mathew Varidel ◽  
Michael Pracy ◽  
Scott Croom ◽  
Matt S. Owers ◽  
Elaine Sadler
Keyword(s):  
Star Formation ◽  
Velocity Gradient ◽  
Velocity Dispersion ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Local Effect ◽  
Line Of Sight ◽  
Mean Velocity ◽  
Gas Kinematics ◽  
Integral Field Spectroscopy

AbstractWe have used integral field spectroscopy of a sample of six nearby (z ~ 0.01–0.04) high star-formation rate ($\text{SFR} \sim 10\hbox{--}40$$\text{M}_\odot \text{ yr$^{-1}$}$) galaxies to investigate the relationship between local velocity dispersion and star-formation rate on sub-galactic scales. The low-redshift mitigates, to some extent, the effect of beam smearing which artificially inflates the measured dispersion as it combines regions with different line-of-sight velocities into a single spatial pixel. We compare the parametric maps of the velocity dispersion with the Hα flux (a proxy for local star-formation rate), and the velocity gradient (a proxy for the local effect of beam smearing). We find, even for these very nearby galaxies, the Hα velocity dispersion correlates more strongly with velocity gradient than with Hα flux—implying that beam smearing is still having a significant effect on the velocity dispersion measurements. We obtain a first-order non parametric correction for the unweighted and flux weighted mean velocity dispersion by fitting a 2D linear regression model to the spaxel-by-spaxel data where the velocity gradient and the Hα flux are the independent variables and the velocity dispersion is the dependent variable; and then extrapolating to zero velocity gradient. The corrected velocity dispersions are a factor of ~ 1.3–4.5 and ~ 1.3–2.7 lower than the uncorrected flux-weighted and unweighted mean line-of-sight velocity dispersion values, respectively. These corrections are larger than has been previously cited using disc models of the velocity and velocity dispersion field to correct for beam smearing. The corrected flux-weighted velocity dispersion values are σm ~ 20–50 km s−1.

scholarly journals Planetary Nebulae and their parent stellar populations. Tracing the mass assembly of M87 and Intracluster light in the Virgo cluster core

2015 ◽  
Vol 11 (S317) ◽  
pp. 69-76
Author(s):  
Magda Arnaboldi ◽  
Alessia Longobardi ◽  
Ortwin Gerhard
Keyword(s):  
Planetary Nebulae ◽  
Major Axis ◽  
Large Magellanic Cloud ◽  
Virgo Cluster ◽  
Star Formation History ◽  
Cluster Core ◽  
Line Of Sight ◽  
Cluster Galaxy ◽  
Mass Assembly ◽  
Intracluster Light

AbstractThe diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centers. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies. We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 deg2region centered on the brightest cluster galaxy NGC 4486 (M87) in the Virgo cluster core, carried out with SuprimeCam@Subaru and FLAMES-GIRAFFE@VLT. Two planetary nebulae populations are identified out to 150 kpc distance from the center of M87. One population is associated with the M87 halo and the second one with the intracluster light in the Virgo cluster core. They have different line-of-sight velocity and spatial distributions, as well as different planetary nebulae specific frequencies and luminosity functions. The intracluster planetary nebulae in the surveyed region correspond to a luminosity of four times the luminosity of the Large Magellanic Cloud. The M87 halo planetary nebulae trace an older, more metal-rich, parent stellar population. A substructure detected in the projected phase-space of the line-of-sight velocity vs. major axis distance for the M87 halo planetary nebulae provides evidence for the recent accretion event of a satellite galaxy with luminosity twice that of M33. The satellite stars were tidally stripped about 1 Gyr ago, and reached apocenter at a major axis distance of 60–90 kpc from the center of M87. The M87 halo is still growing significantly at the distances where the substructure is detected.

scholarly journals The ultra-diffuse galaxy NGC 1052-DF2 with MUSE

2019 ◽  
Vol 625 ◽  
pp. A76 ◽  
Author(s):  
Eric Emsellem ◽  
Remco F. J. van der Burg ◽  
Jérémy Fensch ◽  
Tereza Jeřábková ◽  
Anita Zanella ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Major Axis ◽  
Mean Velocity ◽  
Central Value ◽  
Very Large Telescope ◽  
The Mean ◽  
Integral Field Spectrograph ◽  
Stellar Body ◽  
Kinematic Axis

The so-called ultra-diffuse galaxy NGC 1052-DF2 was announced to be a galaxy lacking dark matter based on a spectroscopic study of its constituent globular clusters. Here we present the first spectroscopic analysis of the stellar body of this galaxy using the MUSE integral-field spectrograph at the (ESO) Very Large Telescope. The MUSE datacube simultaneously provides DF2’s stellar velocity field and systemic velocities for seven globular clusters (GCs). We further discovered three planetary nebulae (PNe) that are likely part of this galaxy. While five of the clusters had velocities measured in the literature, we were able to confirm the membership of two more candidates through precise radial velocity measurements, which increases the measured specific frequency of GCs in DF2. The mean velocity of the diffuse stellar body, 1792.9+1.4−1.8 km s−1, is consistent with the mean globular cluster velocity. We detect a weak but significant velocity gradient within the stellar body, with a kinematic axis close to the photometric major axis, making it a prolate-like rotator. We estimate a velocity dispersion from the clusters and PNe of σint = 10.6−2.3+3.9 km s−1. The velocity dispersion σDF2⋆(Re) for the stellar body within one effective radius is 10.8+3.2−4.0 km s−1. Considering various sources of systemic uncertainties, this central value varies between 5 and 13 km s−1, and we conservatively report a 95% confidence upper limit to the dispersion within one Re of 21 km s−1. We provide updated mass estimates based on these dispersions corresponding to the different distances to NGC 1052-DF2 that have been reported in the recent literature.

scholarly journals Out of sight, out of mind? The impact of correlated clustering in substructure lensing

2021 ◽  
Author(s):  
Alexandres Lazar ◽  
James S Bullock ◽  
Michael Boylan-Kolchin ◽  
Robert Feldmann ◽  
Onur Çatmabacak ◽  
...  
Keyword(s):  
Dark Matter ◽  
Principal Axis ◽  
Major Axis ◽  
Line Of Sight ◽  
Gravitational Lenses ◽  
Local Clustering ◽  
Analytic Expression ◽  
Halo Masses ◽  
The Impact

Abstract A promising route for revealing the existence of dark matter structures on mass scales smaller than the faintest galaxies is through their effect on strong gravitational lenses. We examine the role of local, lens-proximate clustering in boosting the lensing probability relative to contributions from substructure and unclustered line-of-sight (LOS) haloes. Using two cosmological simulations that can resolve halo masses of Mhalo ≃ 109 M⊙ (in a simulation box of length Lbox ∼ 100 Mpc) and 107 M⊙ (Lbox ∼ 20 Mpc), we demonstrate that clustering in the vicinity of the lens host produces a clear enhancement relative to an assumption of unclustered haloes that persists to >20 Rvir. This enhancement exceeds estimates that use a two-halo term to account for clustering, particularly within 2 − 5 Rvir. We provide an analytic expression for this excess, clustered contribution. We find that local clustering boosts the expected count of 109 M⊙ perturbing haloes by ${\sim }35{{\ \rm per\ cent}}$ compared to substructure alone, a result that will significantly enhance expected signals for low-redshift (zl ≃ 0.2) lenses, where substructure contributes substantially compared to LOS haloes. We also find that the orientation of the lens with respect to the line of sight (e.g. whether the line of sight passes through the major axis of the lens) can also have a significant effect on the lensing signal, boosting counts by an additional $\sim 50{{\ \rm per\ cent}}$ compared to a random orientations. This could be important if discovered lenses are biased to be oriented along their principal axis.

scholarly journals Probing non-spherical dark halos in the Galactic dwarf satellites

2013 ◽  
Vol 9 (S298) ◽  
pp. 411-411
Author(s):  
Kohei Hayashi ◽  
Masashi Chiba
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Velocity Dispersion ◽  
Line Of Sight ◽  
Spherical Structure ◽  
Spherical Models ◽  
Galactic Satellites ◽  
Best Fitting

AbstractWe construct axisymmetric mass models for dwarf spheroidal (dSph) galaxies in the Milky Way to obtain realistic limits on the non-spherical structure of their dark halos. This is motivated by the fact that the observed luminous parts of the dSphs are actually non-spherical and cold dark matter models predict non-spherical virialized dark halos on sub-galactic scales. Applying these models to line-of-sight velocity dispersion profiles along three position angles in six Galactic satellites, we find that the best fitting cases for most of the dSphs yield not spherical but oblate and flattened dark halos. We also find that the mass of the dSphs enclosed within inner 300 pc varies depending on their total luminosities, contrary to the conclusion of previous spherical models. This suggests the importance of considering non-spherical shapes of dark halos in dSph mass models.

scholarly journals Doppler Shift of Radio Signals Transmitted between Orbiting Satellites

1982 ◽  
Vol 35 (2) ◽  
pp. 155 ◽  
Author(s):  
PL Dyson ◽  
JA Bennett
Keyword(s):  
Electron Concentration ◽  
Doppler Shift ◽  
Rate Of Change ◽  
Line Of Sight ◽  
Concentration Gradients ◽  
Mean Velocity ◽  
Radio Signals ◽  
The Mean ◽  
The Moment ◽  
The Individual

A general expression, applicable at VHF and above, is derived for the Doppler shift of radio signals transmitted between two satellites embedded in the ionosphere. The Doppler shift is made up of several contributions which depend on (a) the rate of change of the free space path between the satellites, (b) the components, perpendicular to the line of sight between the satellites, of both the mean velocity of the satellites and the electron concentration gradients, (c) the moment of the perpendicular electron concentration gradients and the deviations from the mean of the individual satellite perpendicular velocities, (d) the velocity components along the line of sight between the satellites, and the electron concentration values at each satellite, and (e) changes occurring in the ionosphere with time.

scholarly journals Radial Velocity Study of NGC 6712

1988 ◽  
Vol 126 ◽  
pp. 659-660
Author(s):  
J. Grindlay ◽  
C. Bailyn ◽  
R. Mathieu ◽  
D. Latham
Keyword(s):  
Radial Velocity ◽  
Velocity Dispersion ◽  
Line Of Sight ◽  
Ccd Photometry ◽  
The Mean

We report MMT Echelle radial velocity observations of 52 giants within 3 core radii of the center of NGC 6712. The mean radial velocity of these stars is −107.5 km/s, with a line of sight velocity dispersion of 4.0 km/s. We use these data, together with CCD photometry of the cluster, to derive a mass to light ratio for the center of the cluster of 0.7, an unusually low value.

scholarly journals About the Coma Cluster (Progress Report)

1987 ◽  
Vol 117 ◽  
pp. 112-112
Author(s):  
D. Gerbal ◽  
G. Mathez ◽  
A. Mazure ◽  
E. Salvadore-Solé
Keyword(s):  
Total Mass ◽  
Velocity Dispersion ◽  
Dynamical Evolution ◽  
Dynamical Analysis ◽  
Radial Dependence ◽  
Cluster Center ◽  
Coma Cluster ◽  
Massive Galaxies ◽  
Relaxation Effects ◽  
The Galaxy

The study of the dynamics of the Coma Cluster is of interest for several reasons. First, there exists a great deal of observational information about the cluster, including data on morphology, magnitude, color and redshift for the galaxies, and reasonably detailed x-ray data for the hot gas. Second, the present dynamical state of the cluster is reasonably well-defined. In addition, the segregation of the more luminous (≡ massive) galaxies towards the cluster center shows that two-body relaxation effects are well-advanced (Capelato et al. 1980). The profile of velocity dispersion with radius shows that in the outer parts of the cluster the galaxy velocities are non-isothermal (des Forêts et al. 1984). There is, however, evidence of continuing dynamical evolution. The velocity field of the galaxies at large distances from the center of the cluster suggests continuing infall (Capelato et al. 1982), and two sub-condensations are located in the inner regions (Mazure and Proust 1986). A new dynamical analysis for the cluster is being carried out in two stages. First, a relaxed model with a wide mass spectrum (c.f. Inagaki 1980) is fitted to the data. The contribution of the intergalactic gas is taken into account. With HO = 75 km/sec/Mpc, the total mass within a 3° radius of the center is ∼ 1.5 × 1015 M⊙, of which ∼ 30% is in the intergalactic medium, and M/L ∼ 75 M⊙/L⊙. The ratio of specific energies of the galaxies and the gas is ∼ 1.1, i.e., there is no scale-height problem (these results are described more fully by Gerbal et al. 1986). A second “model independent” analysis using the profiles of the galactic density and velocity dispersion gives the radial dependence of the galactic mass, the gas mass and also gives the total mass, which is found to be ∼ 1.1 × 1015 M⊙ within 3° (Gerbal et al. 1984).

A Segmentation Model for the Targeted Marketing of Consumer Durables

1995 ◽  
Vol 32 (4) ◽  
pp. 463-469 ◽  
Author(s):  
Barry L. Bayus ◽  
Raj Mehta
Keyword(s):  
Mixture Distribution ◽  
Finite Mixture ◽  
Consumer Durables ◽  
Empirical Application ◽  
Household Characteristics ◽  
Household Data ◽  
Potential Consumer ◽  
Consumer Durable ◽  
Managerial Implications ◽  
Targeted Marketing

The authors use finite mixture distribution theory to develop a segmentation model for targeting potential consumer durable buyers. The model enables them to identify simultaneously durable replacer segments on the basis of household characteristics and product ages and determine which of the household characteristics are significant predictors of segment membership. Using household data for five home appliances, the authors present an empirical application of the model. They also discuss managerial implications and uses of this approach.

scholarly journals Inclination of the HCO+ Torus in the NGC7027 Molecular Envelope

1994 ◽  
Vol 140 ◽  
pp. 148-149
Author(s):  
Issei Yamamura ◽  
Shuji Deguchi
Keyword(s):  
Mass Loss ◽  
Major Axis ◽  
Line Of Sight ◽  
Model Calculations ◽  
Ngc 7027 ◽  
Molecular Envelope

AbstractWe have determined the inclination of the axis of the HCO+torus in NGC 7027 to the line of sight, based on interferometrie observations and model calculations. We found that the deduced inclination of the HCO+ torus is misaligned with the inclination of the major axis of the ionized core. The result may imply the precession of the axis of the axisymmetric mass loss.

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