scholarly journals The Dark Halo – Spheroid Conspiracy

2012 ◽  
Vol 8 (S295) ◽  
pp. 208-208
Author(s):  
Rhea-Silvia Remus ◽  
Andreas Burkert ◽  
Klaus Dolag ◽  
Peter H. Johansson ◽  
Thorsten Naab ◽  
...  
Keyword(s):  
Elliptical Galaxies ◽  
Total Density ◽  
Dark Halo ◽  
Coma Cluster ◽  
Density Profiles ◽  
Stellar Component ◽  
Strong Lensing ◽  
The Galaxy ◽  
Good Agreement

AbstractObservational results from strong lensing and dynamical modeling indicate that the total density profiles of early-type galaxies are close to isothermal, i.e. ρtot ∝ rγ with γ ≈ −2. To understand the origin of this universal slope we study a set of simulated spheroids formed in cosmological hydrodynamical zoom-in simulations (see Oser et al. 2010 for more details). We find that the total stellar plus dark matter density profiles of all our simulations on average can be described by a power law with a slope of γ ≈ −2.1, with a tendency towards steeper slopes for more compact, lower mass ellipticals, while the total intrinsic velocity dispersion is flat for all simulations, independent of the values of γ. Our results are in good agreement with observations of Coma cluster ellipticals (Thomas et al. 2007) and results from strong lensing (Sonnenfeld et al. 2012). We find that for z ≳ 2 the majority of the stellar build-up occurs through in-situ star formation, i.e. the gas falls to the center of the galaxy and forms stars, causing the galaxy to be more compact and thus the stellar component to be more dominant. As a result, the total density slopes at z ≈ 2 are generally steeper (around γ ≈ −3). Between z = 2 and z = 0 galaxies grow mostly through dry merging, with each merging event shifting the slope more towards γ ≈ −2. We conclude from our simulations that the steepness of the slope of present day galaxies is a signature of the importance of mostly dry mergers in the formation of an elliptical, and suggest that all elliptical galaxies will with time end up in a configuration with a density slope of γ ≈ −2. For a more detailed analysis with a larger sample of simulations see Remus et al. (2013).

scholarly journals The Dark Halo – Spheroid Conspiracy Reloaded: Evolution with Redshift

2014 ◽  
Vol 10 (S311) ◽  
pp. 116-119 ◽  
Author(s):  
Rhea-Silvia Remus ◽  
Klaus Dolag ◽  
Andreas Burkert
Keyword(s):  
Power Law ◽  
Elliptical Galaxies ◽  
Total Density ◽  
Dark Halo ◽  
Density Profiles ◽  
Opposite Trend ◽  
Stellar Component ◽  
Strong Lensing ◽  
Single Power ◽  
Spheroidal Galaxies

AbstractThe total density profiles of elliptical galaxies can be fit by a single power law, i.e., ρtot ∝ rγ with γ ≈ −2. While strong lensing observations show a tendency for the slopes to become flatter with increasing redshift, simulations indicate an opposite trend. To understand this discrepancy, we study a set of simulated spheroids formed within the cosmological framework. From our simulations we find that the steepness of the total density slope correlates with the compactness of the stellar component within the half-mass radius, and that spheroidal galaxies tend to be more compact at high redshifts than their present-day counterparts. While both these results are in agreement with observations, the observed trend of the total density slope with redshift remains in contradiction to the results from simulations.

scholarly journals Evolution of the Coronae in Early-Type Galaxies

1990 ◽  
Vol 115 ◽  
pp. 240-244
Author(s):  
L.P. David ◽  
W. Forman ◽  
C. Jones
Keyword(s):  
Mass Loss ◽  
Numerical Simulations ◽  
Elliptical Galaxies ◽  
Compact Groups ◽  
Type I ◽  
Dark Halo ◽  
Early Type ◽  
X Ray ◽  
Galactic Winds ◽  
The Galaxy

AbstractWe present numerical simulations of the gaseous coronae in elliptical galaxies. These models consist of a modified King profile for the luminous portion of the galaxy and an isothermal dark halo. We include evolving stellar mass loss from planetary nebulae, and type I and II supernovae. Our models show that elliptical galaxies are likely to produce strong galactic winds at early times with x-ray luminosities of 1042 — 1044 ergs s-1 and temperatures of 10 keV. Galaxies can lose approximately 10-30% of their initial luminous mass in the wind which has an oxygen-to-iron ratio twice the solar value. Since elliptical galaxies are a principle component of rich clusters and compact groups this early wind phase affects the metallicity and temperature of the intracluster medium.

scholarly journals Features of Fundamental Plane for Early-Type Galaxies by Clausius' Virial theory

2006 ◽  
Vol 2 (S235) ◽  
pp. 134-134
Author(s):  
L. Secco
Keyword(s):  
Order Approximation ◽  
Early Type ◽  
Density Profiles ◽  
Fundamental Plane ◽  
First Order ◽  
Thermodynamical Properties ◽  
Cosmological Scenario ◽  
Stellar Component ◽  
First Order Approximation ◽  
Good Agreement

AbstractThe theory of the Fundamental Plane (FP) proposed by Secco (2005) is based on the existence of a maximum in the Clausius' Virial (CV) potential energy of a stellar component when it is completely embedded inside a dark matter (DM) halo. At the first order approximation the theory was developed by modeling the two-components with two power-law density profiles and it produces some expectations in fairly good agreement with the observations. We add other predictions of the theory at the same level of approximation about the Zone of Exclusion (ZOE) in k-space and its possible relationship with cosmological scenario. Some of the consequences of the thermodynamical properties of CV maximum are also taken into account.

scholarly journals The RAVE Survey: Constraining the Local Galactic Escape Speed

2006 ◽  
Vol 2 (S235) ◽  
pp. 137-137 ◽  
Author(s):  
Martin C. Smith ◽  
G. R. Ruchti ◽  
A. Helmi ◽  
R. F. G. Wyse ◽  
Keyword(s):  
Galaxy Formation ◽  
Precise Measurement ◽  
Dark Halo ◽  
Escape Velocity ◽  
Radial Extent ◽  
The Galaxy ◽  
Virial Mass ◽  
Halo Masses ◽  
Escape Speed ◽  
Good Agreement

AbstractWe report new constraints on the local escape speed of our Galaxy. Our analysis is based on a sample of high velocity stars from the RAVE survey and two previously published datasets (the Geneva-Copenhagen survey and the Beers et al. catalogue of metal-poor stars). We use cosmological simulations of disk galaxy formation to motivate our assumptions on the shape of the velocity distribution, allowing for a significantly more precise measurement of the escape velocity compared to previous studies. We find that the escape velocity lies within the range 492 km s−1 < vesc <594 kms (90% confidence), with a median likelihood of 536 kms. The fact that v2esc is significantly greater than 2v2circ implies that there must be a significant amount of mass exterior to the Solar circle, i.e. this convincingly demonstrates the presence of a dark halo in the Galaxy. For a simple isothermal halo, one can calculate that the minimum radial extent is ~54 kpc. We use our constraints on vesc to determine the mass of the Milky Way halo for three halo profiles. For example, an adiabatically contracted NFW halo model results in a virial mass of 1.31+0.97−0.49 × 1012M⊙ and virial radius of 297+60−44 kpc (90% confidence). For this model the circular velocity at the virial radius is 141+27−19kms. Although our halo masses are model dependent, we find that they are in good agreement with each other.

Probing the luminous and dark matter profiles in the inner regions of a group-scale lens at z = 0.6

2019 ◽  
Vol 15 (S341) ◽  
pp. 318-319
Author(s):  
Mônica Tergolina ◽  
Cristina Furlanetto ◽  
Marina Trevisan
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Total Density ◽  
Density Profiles ◽  
High Resolution Data ◽  
Galaxy Groups ◽  
The Galaxy ◽  
Group Members ◽  
The Universe

AbstractStudying the density profiles of galaxy groups offers an important insight on how large-scale structure in the Universe formed and evolved, since galaxy groups bridge the gap between individual galaxies and galaxy clusters. We aim to probe the total density profile of the galaxy group that is gravitational lensing HELMS18, a submillimeter galaxy at z = 2.39 from the Herschel’s HerMES Large Mode Survey (HELMS), by combining strong gravitational lensing with kinematics of the centrally-located galaxies and kinematics of the group members. We will use high-resolution data of HELMS18 obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) and multi-object spectroscopic data of the group members from Gemini-GMOS. Our final goal is to combine these observations to probe the stellar and dark matter density profiles and to build a complete description of this galaxy group.

scholarly journals Luminous and dark matter density profiles in the inner regions of a group-scale lens at z = 0.6

2019 ◽  
Vol 15 (S352) ◽  
pp. 295-296
Author(s):  
Mônica Tergolina ◽  
Cristina Furlanetto ◽  
Marina Trevisan
Keyword(s):  
Gravitational Lensing ◽  
Large Scale ◽  
Total Density ◽  
Density Profiles ◽  
High Resolution Data ◽  
Galaxy Groups ◽  
The Galaxy ◽  
Group Members ◽  
The Universe ◽  
Stellar Density

AbstractDensity profiles of galaxy groups can provide an insight on how large-scale structure in the Universe formed and evolved, since galaxy groups bridge the gap between individual galaxies and galaxy clusters. Studying the galaxy group that is gravitational lensing HELMS18, a submillimeter galaxy at z = 2.39 from the Herschel’s HerMES Large Mode Survey (HELMS), we aim to probe the total density profile by combining strong gravitational lensing with kinematics of the centrally-located galaxies and kinematics of the group members. We have high-resolution data of HELMS18 obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) and multi-object spectroscopic data of the group members from Gemini-GMOS. Our main goal is to match these observations to probe the DM and stellar density profiles and to establish a complete description of this galaxy group.

The 3D Topology of the Clausius Virial for Two Component Dynamical Models of Elliptical Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 146-146
Author(s):  
T. Valentinuzzi ◽  
L. Secco ◽  
M. D'Onofrio ◽  
R. Caimmi ◽  
D. Bindoni
Keyword(s):  
Potential Energy ◽  
Power Law ◽  
Large Scale ◽  
Elliptical Galaxies ◽  
Dark Halo ◽  
Dynamical Models ◽  
Density Profiles ◽  
Two Component ◽  
3D Topology ◽  
Scale Length

AbstractAs found in Secco (2000, 2001), the presence of a (non-baryonic) dark halo in large-scale celestial objects, can induce a scale length on the luminous spheroid through the occurrence of an unexpected maximum in the virial potential energy (Clausius Virial, CV). The above mentioned investigations were grounded on two cored power law density profiles, but the same result is shown to hold for more refined and realistic models.

scholarly journals Theoretical Aspects of Galaxy Dynamics Using Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 615-616
Author(s):  
Anne Mathieu
Keyword(s):  
Planetary Nebulae ◽  
Elliptical Galaxies ◽  
Emission Lines ◽  
Absorption Lines ◽  
Dark Halo ◽  
Galaxy Dynamics ◽  
The Galaxy ◽  
Stellar Body

The dynamics of the outer regions of elliptical galaxies is still poorly known. Their lack of gas means that it is not possible to use the usual optical and 21cm emission lines to determine the kinematics out to large radii, and the faintness of their stellar body means that data calculated using absorption lines are limited to the inner part of the galaxy. It is only by measuring the kinematics out to several optical scalelengths that one gets any unambiguous measure of the dark halo properties (Kent 1986).

scholarly journals The number of globular clusters around the iconic UDG DF44 is as expected for dwarf galaxies

2020 ◽  
Author(s):  
Teymoor Saifollahi ◽  
Ignacio Trujillo ◽  
Michael A Beasley ◽  
Reynier F Peletier ◽  
Johan H Knapen
Keyword(s):  
Total Mass ◽  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Dark Halo ◽  
Coma Cluster ◽  
A Value ◽  
The Galaxy ◽  
Selection Of

Abstract There is a growing consensus that the vast majority of ultra-diffuse galaxies (UDGs) are dwarf galaxies. However, there remain a few UDGs that seem to be special in terms of their globular cluster (GC) systems. In particular, according to some authors, certain UDGs exhibit large GC populations when compared to expectations from their stellar (or total) mass. Among these special UDGs, DF44 in the Coma cluster is one of the better-known examples. DF44 has been claimed to have a relatively high number of GCs, $N_{GC}=74^{+18}_{-18}$, for a stellar mass of only 3 × 108M⊙ which would indicate a much larger dark halo mass than dwarfs of similar stellar mass. In this paper we revisit this number and, contrary to previous results, find $N_{GC}=21^{+7}_{-9}$ assuming that the distribution of the GCs follows the same geometry as the galaxy. If we assume that the GCs around DF44 are distributed in a (projected) circularly symmetric way and, if we use a less strict criterion for the selection of the GCs, we find $N_{GC}=18^{+23}_{-12}$. Making use of the MGC − Mhalo relation, this number of GCs suggests a dark matter halo mass of $M_{halo}=1.1^{+0.4}_{-0.5} \times 10^{11} M_{\odot }$, a value which is consistent with the expected total mass for DF44 based on its velocity dispersion, $\sigma =33^{+3}_{-3}$ km s−1. We conclude that the number of GCs around DF44 is as expected for regular dwarf galaxies of similar stellar mass and DF44 is not extraordinary in this respect.

Atomic Layer Deposition of LiF and Lithium Ion Conducting (AlF3)(LiF)x Alloys Using Trimethylaluminum, Lithium Hexamethyldisilazide and Hydrogen Fluoride

2017 ◽  
Author(s):  
Younghee Lee ◽  
Daniela M. Piper ◽  
Andrew S. Cavanagh ◽  
Matthias J. Young ◽  
Se-Hee Lee ◽  
...  
Keyword(s):  
Lithium Ion ◽  
Atomic Layer ◽  
Mass Gain ◽  
Alloy Film ◽  
Ex Situ ◽  
X Ray ◽  
Layer Deposition ◽  
Ion Conducting ◽  
Good Agreement

<div>Atomic layer deposition (ALD) of LiF and lithium ion conducting (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloys was developed using trimethylaluminum, lithium hexamethyldisilazide (LiHMDS) and hydrogen fluoride derived from HF-pyridine solution. ALD of LiF was studied using in situ quartz crystal microbalance (QCM) and in situ quadrupole mass spectrometer (QMS) at reaction temperatures between 125°C and 250°C. A mass gain per cycle of 12 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C and decreased at higher temperatures. QMS detected FSi(CH<sub>3</sub>)<sub>3</sub> as a reaction byproduct instead of HMDS at 150°C. LiF ALD showed self-limiting behavior. Ex situ measurements using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) showed a growth rate of 0.5-0.6 Å/cycle, in good agreement with the in situ QCM measurements.</div><div>ALD of lithium ion conducting (AlF3)(LiF)x alloys was also demonstrated using in situ QCM and in situ QMS at reaction temperatures at 150°C A mass gain per sequence of 22 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C. Ex situ measurements using XRR and SE showed a linear growth rate of 0.9 Å/sequence, in good agreement with the in situ QCM measurements. Stoichiometry between AlF<sub>3</sub> and LiF by QCM experiment was calculated to 1:2.8. XPS showed LiF film consist of lithium and fluorine. XPS also showed (AlF<sub>3</sub>)(LiF)x alloy consists of aluminum, lithium and fluorine. Carbon, oxygen, and nitrogen impurities were both below the detection limit of XPS. Grazing incidence X-ray diffraction (GIXRD) observed that LiF and (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film have crystalline structures. Inductively coupled plasma mass spectrometry (ICP-MS) and ionic chromatography revealed atomic ratio of Li:F=1:1.1 and Al:Li:F=1:2.7: 5.4 for (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film. These atomic ratios were consistent with the calculation from QCM experiments. Finally, lithium ion conductivity (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film was measured as σ = 7.5 × 10<sup>-6</sup> S/cm.</div>

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