scholarly journals The σ-bump in elliptical galaxies – a signature of major mergers?

2016 ◽  
Vol 11 (S321) ◽  
pp. 122-122
Author(s):  
Anna T. P. Schauer ◽  
Felix Schulze ◽  
Rhea-Silvia Remus ◽  
Andreas Burkert
Keyword(s):  
Power Law ◽  
Globular Clusters ◽  
Velocity Dispersion ◽  
Elliptical Galaxies ◽  
Equal Mass ◽  
Disk Galaxies ◽  
Two Dimensional ◽  
Mass Ratios ◽  
Observable Feature ◽  
First Time

AbstractThe stellar radial velocity dispersion profiles of elliptical galaxies can be well described by a power-law σ(r)∝r−β. We analyze a set of elliptical galaxies formed by major mergers of isolated disk galaxies with mass ratios of 1:1 and 3:1 for several orbital configurations (Johansson et al. 2009). The galaxies in our sample show a deviation from the power-law at 1 − 3Reff, which we term the σ-bump (Schauer et al. 2014). This feature is most prominent in remnants of 1:1 mergers and weakens for remnants of mergers with smaller mass ratios, indicating that the σ-bump is a signature of an equal mass merger. The σ-bump does not vanish with time but stays constant once it has formed, in contrast to shells. It can be seen under all projections, making it an observable feature in the outskirts of elliptical galaxies. We indeed identify three possible σ-bump candidates in the sample of 12 SLUGGS-survey ellipticals studied by Pota et al. (2013), who use globular clusters as tracers for the outer stellar halos (see Schauer et al. 2014, for more details). For further comparisons, we here provide for the first time a two dimensional map of the velocity dispersion of one simulated σ-bump galaxy, to identify the σ-bump in observations of kinematic maps out to several Reff. The σ-bump appears as a global ring-like feature if seen face-on and as an extended box-like feature in its edge-on projection.

scholarly journals The Dynamical Mass of the Young Cluster W3 in NGC 7252: Heavy-Weight Globular Cluster or Ultra-Compact Dwarf Galaxy?

2005 ◽  
Vol 13 ◽  
pp. 169-170
Author(s):  
Claudia Maraston ◽  
N. Bastian ◽  
R. P. Saglia ◽  
Markus Kissler-Patig ◽  
François Schweizer ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Elliptical Galaxies ◽  
Star Cluster ◽  
Dynamical Mass ◽  
Fundamental Plane ◽  
Dwarf Elliptical Galaxies ◽  
First Time

AbstractWe have measured the dynamical mass of the highly luminous star cluster W3 in the young merger remnant galaxy NGC 7252. The value is Mdyn = (8 ± 2) × 107M⊙, and represents the highest dynamically-confirmed mass for an extra-galactic star cluster so far. The dynamical mass is in excellent agreement with the luminous mass (Maraston et al. 2001). This results from the use of stellar population models that include correctly the brightest AGB stellar phase, dominant in young stellar populations. To classify W3, we employ the fundamental plane of stellar systems (Bender, Burstein & Faber 1992), for the first time in these kinds of studies. We find that W3 lies far from typical Milky Way globular clusters, but it is also far from the heavyweights ωCen in the Milky Way and G1 in M31, because it is too extended for its mass, and from dwarf elliptical galaxies because it is much more compact for its mass. Instead W3 lies close to the ultra-compact Fornax objects (Drinkwater et al. 2003) and to the compact elliptical M32, possibly shedding light on the still mysterious nature of these objects. A previously deserted region of the fundamental plane starts to be populated.

scholarly journals Kinematics of multiple stellar populations in Globular Clusters with Gaia

2019 ◽  
Vol 14 (S351) ◽  
pp. 281-284
Author(s):  
G. Cordoni ◽  
A. P. Milone ◽  
A. Mastrobuono-Battisti ◽  
A. F. Marino ◽  
E. P. Lagioia ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Stellar Populations ◽  
Field Of View ◽  
Large Field ◽  
Proper Motions ◽  
Physical Processes ◽  
Internal Dynamics ◽  
Data Release ◽  
First Time

AbstractThe internal dynamics of multiple stellar populations in Globular Clusters (GCs) provides unique constraints on the physical processes responsible for their formation. Specifically, the present-day kinematics of cluster stars, such as rotation and velocity dispersion, seems to be related to the initial configuration of the system. In recent work (Milone et al. 2018), we analyzed for the first time the kinematics of the different stellar populations in NGC 0104 (47 Tucanae) over a large field of view, exploiting the Gaia Data Release 2 proper motions combined with multi-band ground-based photometry. In this paper, based on the work by Cordoni et al. (2019), we extend this analysis to six GCs, namely NGC 0288, NGC 5904 (M 5), NGC 6121 (M 4), NGC 6752, NGC 6838 (M 71) and further explore NGC 0104. Among the analyzed clusters only NGC 0104 and NGC 5904 show significant rotation on the plane of the sky. Interestingly, multiple stellar populations in NGC 5904 exhibit different rotation curves.

scholarly journals Keck Cosmic Web Imager (KCWI) spectra of globular clusters and ultracompact dwarfs in the halo of M87

2020 ◽  
Vol 497 (1) ◽  
pp. 765-775
Author(s):  
Duncan A Forbes ◽  
Anna Ferré-Mateu ◽  
Mark Durré ◽  
Jean P Brodie ◽  
Aaron J Romanowsky
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Velocity Dispersion ◽  
Population Analysis ◽  
Stellar Populations ◽  
Element Abundances ◽  
Dispersion Profile ◽  
Self Consistent ◽  
First Time

ABSTRACT Using the Keck Cosmic Web Imager, we obtain spectra of several globular clusters (GCs), ultracompact dwarfs (UCDs), and the inner halo starlight of M87, at a similar projected galactocentric radius of ∼5 kpc. This enables us, for the first time, to apply the same stellar population analysis to the GCs, UCDs, and starlight consistently to derive ages, metallicities, and alpha-element abundances in M87. We find evidence for a dual stellar population in the M87 halo light, i.e. an ∼80 per cent component by mass that is old and metal-rich and a ∼20 per cent component that is old but metal-poor. Two red GCs share similar stellar populations to the halo light suggesting they may have formed contemporaneously with the dominant halo component. Three UCDs, and one blue GC, have similar stellar populations, with younger mean ages, lower metallicities, and near solar alpha-element abundances. Combined with literature data, our findings are consistent with the scenario that UCDs are the remnant nucleus of a stripped galaxy. We further investigate the discrepancy in the literature for M87’s kinematics at large radii, favouring a declining velocity dispersion profile. This work has highlighted the need for more self-consistent studies of galaxy haloes.

Compaction of Anisotropic Granular Materials: Symmetry Effects

2006 ◽  
Vol 518 ◽  
pp. 355-360
Author(s):  
Lj. Budinski-Petković ◽  
M. Petković ◽  
Z.M. Jakšić ◽  
S.B. Vrhovac
Keyword(s):  
Numerical Simulation ◽  
Monte Carlo ◽  
Steady State ◽  
Granular Materials ◽  
Power Law ◽  
Symmetry Axis ◽  
Random Sequential Adsorption ◽  
Two Dimensional ◽  
Sequential Adsorption ◽  
First Time

We perform numerical simulation of a lattice model for the compaction of a granular material based on the idea of reversible random sequential adsorption. Reversible random sequential adsorption of objects of various shapes on a two−dimensional triangular lattice is studied numerically by means of Monte Carlo simulations. The growth of the coverage ρ(t) above the jamming limit to its steady−state value ρ∞ is described by a pattern ρ (t) = ρ∞ − ρEβ[−(t/τ)β], where Eβ denotes the Mittag−Leffler function of order β ∈ (0, 1). For the first time, the parameter τ is found to decay with the desorption probability P− according to a power law τ = A P− −γ. Exponent γ is the same for all shapes, γ = 1.29 ± 0.01, but parameter A depends only on the order of symmetry axis of the shape. Finally, we present the possible relevance of the model to the compaction of granular objects of various shapes.

scholarly journals Influence of a Standing Wave Flow-Field on the Dynamics of a Spray Diffusion Flame

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 27
Author(s):  
J. Barry Greenberg ◽  
David Katoshevski
Keyword(s):  
Liquid Phase ◽  
Flow Field ◽  
Standing Wave ◽  
Diffusion Flame ◽  
Stokes Number ◽  
Flame Height ◽  
Wave Flow ◽  
Two Dimensional ◽  
Governing Equations ◽  
First Time

A theoretical investigation of the influence of a standing wave flow-field on the dynamics of a laminar two-dimensional spray diffusion flame is presented for the first time. The mathematical analysis permits mild slip between the droplets and their host surroundings. For the liquid phase, the use of a small Stokes number as the perturbation parameater enables a solution of the governing equations to be developed. Influence of the standing wave flow-field on droplet grouping is described by a specially constructed modification of the vaporization Damkohler number. Instantaneous flame front shapes are found via a solution for the usual Schwab–Zeldovitch parameter. Numerical results obtained from the analytical solution uncover the strong bearing that droplet grouping, induced by the standing wave flow-field, can have on flame height, shape, and type (over- or under-ventilated) and on the existence of multiple flame fronts.

scholarly journals Anisotropy in ω Centauri and 47 Tucanae

1988 ◽  
Vol 126 ◽  
pp. 663-664
Author(s):  
G. Meylan
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Dynamical Models ◽  
Comprehensive Description ◽  
Great Opportunity ◽  
The Galaxy

The southern sky gives us the great opportunity to observe two among the brightest and nearest globular clusters of the Galaxy: ω Cen and 47 Tuc. For these giant clusters, we present the comparison between observations and King-Michie multi-mass dynamical models with anisotropy in the velocity dispersion. A more comprehensive description of this work is to be published (Meylan 1986a,b).

scholarly journals Hunting for intermediate-mass black holes in globular clusters: an astrometric study of NGC 6441

2021 ◽  
Vol 503 (1) ◽  
pp. 1490-1506
Author(s):  
Maximilian Häberle ◽  
Mattia Libralato ◽  
Andrea Bellini ◽  
Laura L Watkins ◽  
Jörg-Uwe Pott ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Angular Resolution ◽  
Hubble Space Telescope ◽  
High Mass ◽  
High Angular Resolution ◽  
Stellar Kinematics ◽  
Intermediate Mass ◽  
The Core ◽  
Large Telescopes

ABSTRACT We present an astrometric study of the proper motions (PMs) in the core of the globular cluster NGC 6441. The core of this cluster has a high density and observations with current instrumentation are very challenging. We combine ground-based, high-angular-resolution NACO@VLT images with Hubble Space Telescope ACS/HRC data and measure PMs with a temporal baseline of 15 yr for about 1400 stars in the centremost 15 arcsec of the cluster. We reach a PM precision of ∼30 µas yr−1 for bright, well-measured stars. Our results for the velocity dispersion are in good agreement with other studies and extend already existing analyses of the stellar kinematics of NGC 6441 to its centremost region never probed before. In the innermost arcsecond of the cluster, we measure a velocity dispersion of (19.1 ± 2.0) km s−1 for evolved stars. Because of its high mass, NGC 6441 is a promising candidate for harbouring an intermediate-mass black hole (IMBH). We combine our measurements with additional data from the literature and compute dynamical models of the cluster. We find an upper limit of $M_{\rm IMBH} \lt 1.32 \times 10^4\, \textrm{M}_\odot$ but we can neither confirm nor rule out its presence. We also refine the dynamical distance of the cluster to $12.74^{+0.16}_{-0.15}$ kpc. Although the hunt for an IMBH in NGC 6441 is not yet concluded, our results show how future observations with extremely large telescopes will benefit from the long temporal baseline offered by existing high-angular-resolution data.

scholarly journals Tetrazine molecules as efficient electronic diversion channel in 2D organic-inorganic perovskites

2021 ◽  
Author(s):  
Ferdinand Lédée ◽  
Pierre Audebert ◽  
Gaëlle Trippé-Allard ◽  
Laurent Galmiche ◽  
Damien Garrot ◽  
...  
Keyword(s):  
Organic Component ◽  
Two Dimensional ◽  
Diversion Channel ◽  
Halide Perovskites ◽  
First Time

We present the synthesis of two novel two-dimensional (2D) hybrid organic-inorganic halide perovskites incorporating for the first time 100% of a photoactive tetrazine derivative as the organic component. With this...

scholarly journals Galaxy properties as revealed by MaNGA – III. Kinematic profiles and stellar population gradients in S0s

2020 ◽  
Vol 495 (3) ◽  
pp. 2894-2908 ◽  
Author(s):  
H Domínguez Sánchez ◽  
M Bernardi ◽  
F Nikakhtar ◽  
B Margalef-Bentabol ◽  
R K Sheth
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Elliptical Galaxies ◽  
Element Abundance ◽  
High Signal ◽  
Galactocentric Distance ◽  
Massive Galaxies ◽  
Nearby Galaxies ◽  
Mass Functions

ABSTRACT This is the third paper of a series where we study the stellar population gradients (SP; ages, metallicities, α-element abundance ratios, and stellar initial mass functions) of early-type galaxies (ETGs) at $z$ ≤ 0.08 from the Mapping Nearby Galaxies at APO Data Release 15 (MaNGA-DR15) survey. In this work, we focus on the S0 population and quantify how the SP varies across the population as well as with galactocentric distance. We do this by measuring Lick indices and comparing them to SP synthesis models. This requires spectra with high signal-to-noise ratio which we achieve by stacking in bins of luminosity (Lr) and central velocity dispersion (σ0). We find that: (1) there is a bimodality in the S0 population: S0s more massive than $3\times 10^{10}\, \mathrm{M}_\odot$ show stronger velocity dispersion and age gradients (age and σr decrease outwards) but little or no metallicity gradient, while the less massive ones present relatively flat age and velocity dispersion profiles, but a significant metallicity gradient (i.e. [M/H] decreases outwards). Above $2\times 10^{11}\, \mathrm{M}_\odot$, the number of S0s drops sharply. These two mass scales are also where global scaling relations of ETGs change slope. (2) S0s have steeper velocity dispersion profiles than fast-rotating elliptical galaxies (E-FRs) of the same luminosity and velocity dispersion. The kinematic profiles and SP gradients of E-FRs are both more similar to those of slow-rotating ellipticals (E-SRs) than to S0s, suggesting that E-FRs are not simply S0s viewed face-on. (3) At fixed σ0, more luminous S0s and E-FRs are younger, more metal rich and less α-enhanced. Evidently for these galaxies, the usual statement that ‘massive galaxies are older’ is not true if σ0 is held fixed.

scholarly journals Exfoliation in a low boiling point solvent and electrochemical applications of MoO3

2020 ◽  
Vol 11 ◽  
pp. 662-670
Author(s):  
Matangi Sricharan ◽  
Bikesh Gupta ◽  
Sreejesh Moolayadukkam ◽  
H S S Ramakrishna Matte
Keyword(s):  
Energy Storage ◽  
Electrode Material ◽  
Electronic Devices ◽  
High Specific Capacitance ◽  
Two Dimensional ◽  
Energy Storage Devices ◽  
Intrinsic Nature ◽  
Storage Devices ◽  
Scan Rate ◽  
First Time

MoO3 is a versatile two-dimensional transition metal oxide having applications in areas such as energy storage devices, electronic devices and catalysis. To efficiently utilize the properties of MoO3 arising from its two-dimensional nature exfoliation is necessary. In this work, the exfoliation of MoO3 is carried out in 2-butanone for the first time. The achieved concentration of the dispersion is about 0.57 mg·mL−1 with a yield of 5.7%, which are the highest values reported to date. These high values of concentration and yield can be attributed to a favorable matching of energies involved in exfoliation and stabilization of MoO3 nanosheets in 2-butanone. Interestingly, the MoO3 dispersion in 2-butanone retains its intrinsic nature even after exposure to sunlight for 24 h. The composites of MoO3 nanosheets were used as an electrode material for supercapacitors and showed a high specific capacitance of 201 F·g−1 in a three-electrode configuration at a scan rate of 50 mV·s−1.

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