scholarly journals Mass Distribution of the E0 Galaxy NGC 6703 from Absorption Line Profile Kinematics

1999 ◽  
Vol 186 ◽  
pp. 189-190
Author(s):  
O.E. Gerhard ◽  
G. Jeske ◽  
R.P. Saglia ◽  
Ralf Bender
Keyword(s):  
Dark Matter ◽  
Absorption Line ◽  
Mass Distribution ◽  
Line Profile ◽  
Elliptical Galaxies ◽  
Velocity Profiles ◽  
Matter Content ◽  
Orbit Structure ◽  
Extensive Analysis ◽  
Preliminary Account

Absorption line velocity profiles (vps) contain important information on the anisotropy and mass distribution of elliptical galaxies (e.g., Gerhard 1993, Merritt 1993). Here we briefly present results of an extensive analysis of the E0 galaxy NGC 6703 (Gerhard et al. 1997). This work is part of an observational and theoretical program aimed at understanding the orbit structure and dark matter content of ellipticals at intermediate radii (a preliminary account is given in Saglia et al. 1997).

scholarly journals Dust and the observed dark matter content of galaxies

2004 ◽  
Vol 220 ◽  
pp. 343-344 ◽  
Author(s):  
Maarten Baes ◽  
Herwig Dejonghe ◽  
Jonathan I. Davies
Keyword(s):  
Dark Matter ◽  
Interstellar Dust ◽  
Optical Rotation ◽  
Elliptical Galaxies ◽  
Matter Content ◽  
Dark Matter Halo ◽  
Stellar Kinematics ◽  
The Galaxy ◽  
Dust Attenuation ◽  
Radiative Transfer Modeling

Using detailed Monte Carlo radiative transfer modeling, we examine the effects of absorption and scattering by interstellar dust on the observed kinematics of galaxies. Our modeling results have a direct impact on the derivation of the properties of dark matter haloes around both elliptical and spiral galaxies. We find that interstellar dust has a very significant effect on the observed stellar kinematics of elliptical galaxies, in the way that it mimics the presence of a dark matter halo. Taking dust into account in kinematical modeling procedures can reduce or even eliminate the need for dark matter at a few effective radii. Dust profoundly affects the optical rotation curve and stellar kinematics of edge-on disc galaxies. This effect, however, is significantly reduced when the galaxy is more than a few degrees from strictly edge-on. These results demonstrate that dust attenuation cannot be invoked as a possible mechanism to reconcile the discrepancies between the observed shallow slopes of LSB galaxy rotation curves and the dark matter cusps found in CDM cosmological simulations.

scholarly journals The Rotation Curve, Mass Distribution, and Dark Matter Content of the Milky Way from Classical Cepheids

2020 ◽  
Vol 895 (1) ◽  
pp. L12 ◽  
Author(s):  
Iminhaji Ablimit ◽  
Gang Zhao ◽  
Chris Flynn ◽  
Sarah A. Bird
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Rotation Curve ◽  
Milky Way ◽  
Matter Content ◽  
Classical Cepheids

scholarly journals X-Ray Constraints on Dark Matter in Galaxy Clusters and Elliptical Galaxies: A View from Chandra and XMM

2004 ◽  
Vol 220 ◽  
pp. 149-158 ◽  
Author(s):  
David A. Buote
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Elliptical Galaxies ◽  
Matter Content ◽  
The Self ◽  
Radial Density ◽  
Density Profiles ◽  
X Ray ◽  
Matter Model ◽  
Dark Matter Model

X-ray observations with Chandra and XMM are providing valuable new measurements of the dark matter content of elliptical galaxies and galaxy clusters. I review constraints on the radial density profiles and ellipticities of the dark matter in these systems (with an emphasis on clusters) obtained from recent X-ray observations and discuss their implications, especially for the self-interacting dark matter model.

scholarly journals The outer haloes of massive, elliptical galaxies

2009 ◽  
Vol 5 (H15) ◽  
pp. 92-92
Author(s):  
Payel Das ◽  
Ortwin Gerhard ◽  
Flavio de Lorenzi ◽  
Emily McNeil ◽  
Eugene Churazov ◽  
...  
Keyword(s):  
Dark Matter ◽  
Parametric Method ◽  
Elliptical Galaxies ◽  
Matter Content ◽  
Likelihood Method ◽  
Orbital Structure ◽  
Dynamical Models ◽  
X Ray ◽  
Mass Distributions ◽  
Velocity Dispersions

The outer haloes of massive elliptical galaxies are dark-matter dominated regions where stellar orbits have longer dynamical timescales than the central regions and therefore better preserve their formation history. Dynamical models out to large radii suffer from a degeneracy between mass and orbital structure, as the outer kinematics are unable to resolve higher moments of the line-of-sight velocity distribution. We mitigate this degeneracy for a sample of quiescent, massive, nearby ellipticals by determining their mass distributions independently using a non-parametric method on X-ray observations of the surrounding hot interstellar medium. We then create dynamical models using photometric and kinematic constraints consisting of integral-eld, long-slit and planetary nebulae (PNe) data extending to ~50 kpc. The rst two galaxies of our sample, NGC 5846 and NGC 1399, were found to have very shallow pro jected light distributions with a power law index of ~1.5 and a dark matter content of 70–80% at 50 kpc. Spherical Jeans models of the data show that, in the outer haloes of both galaxies, the pro jected velocity dispersions are almost inde- pendent of the anisotropy and that the PNe prefer the lower end of the range of mass distributions consistent with the X-ray data. Using the N-body code NMAGIC, we cre- ated axisymmetric models of NGC 5846 using the individual PNe radial velocities in a likelihood method and found them to be more constraining than the binned velocity dispersions. Characterising the orbital structure in terms of spherically averaged proles of the velocity dispersions we nd σψ > σr > σθ.

scholarly journals X-RAY AND OPTICAL FLUX RATIO ANOMALIES IN QUADRUPLY LENSED QUASARS. II. MAPPING THE DARK MATTER CONTENT IN ELLIPTICAL GALAXIES

2011 ◽  
Vol 744 (2) ◽  
pp. 111 ◽  
Author(s):  
David Pooley ◽  
Saul Rappaport ◽  
Jeffrey A. Blackburne ◽  
Paul L. Schechter ◽  
Joachim Wambsganss
Keyword(s):  
Dark Matter ◽  
Flux Ratio ◽  
Elliptical Galaxies ◽  
Matter Content ◽  
X Ray ◽  
Optical Flux

scholarly journals Phenomenological approach to the modelling of elliptical galaxies: The problem of the mass-to-light ratio

2007 ◽  
pp. 35-42 ◽  
Author(s):  
S. Samurovic
Keyword(s):  
Dark Matter ◽  
Observational Data ◽  
Power Law ◽  
Phenomenological Approach ◽  
Elliptical Galaxies ◽  
Matter Content ◽  
Effective Radius ◽  
Cumulative Mass ◽  
Value Of It

In this paper the problem of the phenomenological modelling of elliptical galaxies using various available observational data is presented. Recently, Tortora, Cardona and Piedipalumbo (2007) suggested a double power law expression for the global cumulative mass-to-light ratio of elliptical galaxies. We tested their expression on a sample of ellipticals for which we have the estimates of the mass-to-light ratio beyond ~ 3 effective radii, a region where dark matter is expected to play an important dynamical role. We found that, for all the galaxies in our sample, we have ? + ? > 0, but that this does not necessarily mean a high dark matter content. The galaxies with higher mass (and higher dark matter content) also have higher value of ?+?. It was also shown that there is an indication that the galaxies with higher value of the effective radius also have higher dark matter content. .

scholarly journals Local elliptical galaxies: Some aspects of theory vs. observations

2007 ◽  
pp. 7-13
Author(s):  
S. Samurovic
Keyword(s):  
Dark Matter ◽  
Elliptical Galaxies ◽  
Matter Content ◽  
Effective Radius ◽  
Cosmological Models ◽  
Bright Galaxy

In this paper we analyze on, the sample of the local elliptical galaxies, some predictions of various cosmological theories. We start with the sample of ellipticals described in Samurovic (2007b) and confront the established concentration parameters and mass-to-light ratios of these objects with various cosmological models, i.e. models given by Navarro, Frank and White (NFW) (1996, 1997) and Burkert (1995), respectively. We find that the bright galaxy (NGC 5846), for which the sum ? + ? is high, can be reasonably modelled by the NFW models. The Burkert model provides rather good predictions of the dark matter content at one effective radius. There is an indication that bright ellipticals (MB >? -21.0) are more dark matter dominated that the fainter ones (MB >? -21.0).

scholarly journals The Large Range of Dark Matter content in Dwarf Galaxies and its Implications

1996 ◽  
Vol 171 ◽  
pp. 435-435
Author(s):  
S.A. Pustilnik ◽  
V.A. Lipovetsky ◽  
J.-M. Martin ◽  
T.X. Thuan
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Range ◽  
Dwarf Galaxy ◽  
Rotational Velocity ◽  
Matter Content ◽  
Optical Observations ◽  
Strong Interactions ◽  
Formation Mechanisms ◽  
Mass Ratio

We present the analysis of a new set of radio and optical observations of a large sample of Byurakan Blue Compact Galaxies. HI spectra were obtained with the Nançay 300-m and Green Bank 43-m radio telescopes. CCD-images were taken with the KPNO 0.9-m and Whipple Observatory 1.2-m telescopes. Dark Matter (DM) to luminous mass ratios in these BCGs were found to vary from about less than 0.5 up to 14. Recent data taken from the literature indicate this same range. This result has important consequences on models of dwarf galaxy formation, indicating possibly different formation mechanisms. The standard CDM model of dwarfs formation requires large DM halos. However the formation of dwarfs as tidal debris resulting from strong interactions of massive spirals leads naturally to dwarfs with low content of DM. On Fig.1 we show DM to luminous mass ratio versus rotational velocity for our BCGs and some other galaxies.

scholarly journals Dark matter-deficient dwarf galaxies form via tidal stripping of dark matter in interactions with massive companions

2021 ◽  
Vol 502 (2) ◽  
pp. 1785-1796
Author(s):  
R A Jackson ◽  
S Kaviraj ◽  
G Martin ◽  
J E G Devriendt ◽  
A Slyz ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Evolution ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Stellar Mass ◽  
Matter Content ◽  
Mass Relation ◽  
Potential Wells ◽  
Tidal Interactions ◽  
New Interactions

ABSTRACT In the standard ΛCDM (Lambda cold dark matter) paradigm, dwarf galaxies are expected to be dark matter-rich, as baryonic feedback is thought to quickly drive gas out of their shallow potential wells and quench star formation at early epochs. Recent observations of local dwarfs with extremely low dark matter content appear to contradict this picture, potentially bringing the validity of the standard model into question. We use NewHorizon, a high-resolution cosmological simulation, to demonstrate that sustained stripping of dark matter, in tidal interactions between a massive galaxy and a dwarf satellite, naturally produces dwarfs that are dark matter-deficient, even though their initial dark matter fractions are normal. The process of dark matter stripping is responsible for the large scatter in the halo-to-stellar mass relation in the dwarf regime. The degree of stripping is driven by the closeness of the orbit of the dwarf around its massive companion and, in extreme cases, produces dwarfs with halo-to-stellar mass ratios as low as unity, consistent with the findings of recent observational studies. ∼30 per cent of dwarfs show some deviation from normal dark matter fractions due to dark matter stripping, with 10 per cent showing high levels of dark matter deficiency (Mhalo/M⋆ < 10). Given their close orbits, a significant fraction of dark matter-deficient dwarfs merge with their massive companions (e.g. ∼70 per cent merge over time-scales of ∼3.5 Gyr), with the dark matter-deficient population being constantly replenished by new interactions between dwarfs and massive companions. The creation of these galaxies is therefore a natural by-product of galaxy evolution and their existence is not in tension with the standard paradigm.

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