Effects of non-vanishing dark matter pressure in the Milky Way Galaxy

2021 ◽  
Vol 508 (1) ◽  
pp. 1543-1554
Author(s):  
K Boshkayev ◽  
T Konysbayev ◽  
E Kurmanov ◽  
O Luongo ◽  
D Malafarina ◽  
...  
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Gravitational Lensing ◽  
Matter Content ◽  
Dark Matter Halo ◽  
Matter Distribution ◽  
Milky Way Galaxy ◽  
The Galaxy ◽  
Dark Matter Distribution ◽  
Inner Parts

ABSTRACT We consider the possibility that the Milky Way’s dark matter halo possesses a non-vanishing equation of state. Consequently, we evaluate the contribution due to the speed of sound, assuming that the dark matter content of the galaxy behaves like a fluid with pressure. In particular, we model the dark matter distribution via an exponential sphere profile in the galactic core, and inner parts of the galaxy whereas we compare the exponential sphere with three widely used profiles for the halo, i.e. the Einasto, Burkert and Isothermal profile. For the galactic core, we also compare the effects due to a dark matter distribution without black hole with the case of a supermassive black hole in vacuum and show that present observations are unable to distinguish them. Finally we investigate the expected experimental signature provided by gravitational lensing due to the presence of dark matter in the core.

scholarly journals Imprint of Pressure on Characteristic Dark Matter Profiles: The Case of ESO0140040

Galaxies ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 74
Author(s):  
Kuantay Boshkayev ◽  
Talgar Konysbayev ◽  
Ergali Kurmanov ◽  
Orlando Luongo ◽  
Marco Muccino
Keyword(s):  
Dark Matter ◽  
Complex Structure ◽  
Matter Content ◽  
Model Parameters ◽  
Matter Distribution ◽  
Density Profiles ◽  
The Galaxy ◽  
Dark Matter Distribution ◽  
Observational Signature

We investigate the dark matter distribution in the spiral galaxy ESO0140040, employing the most widely used density profiles: the pseudo-isothermal, exponential sphere, Burkert, Navarro-Frenk-White, Moore and Einasto profiles. We infer the model parameters and estimate the total dark matter content from the rotation curve data. For simplicity, we assume that dark matter distribution is spherically symmetric without accounting for the complex structure of the galaxy. Our predictions are compared with previous results and the fitted parameters are statistically confronted for each profile. We thus show that although one does not include the galaxy structure it is possible to account for the same dynamics assuming that dark matter provides a non-zero pressure in the Newtonian approximation. In this respect, we solve the hydrostatic equilibrium equation and construct the dark matter pressure as a function for each profile. Consequently, we discuss the dark matter equation of state and calculate the speed of sound in dark matter. Furthermore, we interpret our results in view of our approach and we discuss the role of the refractive index as an observational signature to discriminate between our approach and the standard one.

scholarly journals Luminous and dark matter in early-type lens galaxies

2009 ◽  
Vol 5 (H15) ◽  
pp. 70-70
Author(s):  
C. Grillo
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Gravitational Lensing ◽  
Elliptical Galaxy ◽  
Matter Content ◽  
Effective Radius ◽  
Dark Matter Halo ◽  
Early Type ◽  
The Galaxy ◽  
Lens Galaxies

In the past few years gravitational lensing has allowed astrophysicists to make great progress in the understanding of the internal structure of early-type galaxies. By taking advantage of accurate photometric and spectroscopic measurements, the luminous and dark matter content of lens galaxies can in principle be disentangled (e.g., Grillo et al. 2008, 2009). SDSS J1538+5817 is an extraordinary strong lensing system composed of an elliptical galaxy and two equally-distant sources located, respectively, at redshifts 0.143 and 0.531 (Grillo et al., submitted to ApJ). The sources are lensed into two and four images with an almost complete Einstein ring, covering a rather large region on the lens plane. By using HST/ACS and WFPC2 imaging and NOT/ALFOSC spectroscopy, we have investigated the lens total mass distribution within one effective radius. Then, we have fitted the SDSS multicolor photometry of the galaxy with composite stellar population models to obtain its luminous mass. By combining lensing and photometric measurements, we have estimated the lens mass in terms of luminous and dark matter components and studied the global properties of the dark matter halo. The exceptional lensing configuration of this system has allowed us to conclude that the galaxy dark matter density distribution is shallower and more diffused than the luminous one and the former starts exceeding the latter at a distance of approximately 1.5 times the effective radius. Extending these results to a larger number of lenses would help us to decipher the processes that rule galaxy formation and evolution in the LCDM scenario.

scholarly journals Inner dark matter distribution of the Cosmic Horseshoe (J1148+1930) with gravitational lensing and dynamics

2019 ◽  
Vol 631 ◽  
pp. A40 ◽  
Author(s):  
S. Schuldt ◽  
G. Chirivì ◽  
S. H. Suyu ◽  
A. Yıldırım ◽  
A. Sonnenfeld ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Gravitational Lens ◽  
Wide Field ◽  
Lens System ◽  
Matter Distribution ◽  
Mass Model ◽  
Luminous Matter ◽  
Dark Matter Distribution ◽  
Light Components

We present a detailed analysis of the inner mass structure of the Cosmic Horseshoe (J1148+1930) strong gravitational lens system observed with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). In addition to the spectacular Einstein ring, this systems shows a radial arc. We obtained the redshift of the radial arc counterimage zs, r = 1.961 ± 0.001 from Gemini observations. To disentangle the dark and luminous matter, we considered three different profiles for the dark matter (DM) distribution: a power law profile, the Navarro, Frenk, and White (NFW) profile, and a generalized version of the NFW profile. For the luminous matter distribution, we based the model on the observed light distribution that is fitted with three components: a point mass for the central light component resembling an active galactic nucleus, and the remaining two extended light components scaled by a constant mass-to-light ratio (M/L). To constrain the model further, we included published velocity dispersion measurements of the lens galaxy and performed a self-consistent lensing and axisymmetric Jeans dynamical modeling. Our model fits well to the observations including the radial arc, independent of the DM profile. Depending on the DM profile, we get a DM fraction between 60% and 70%. With our composite mass model we find that the radial arc helps to constrain the inner DM distribution of the Cosmic Horseshoe independently of the DM profile.

Studying the Patterns of the Universe

2011 ◽  
Vol 20 (2) ◽  
Author(s):  
T. Sepp ◽  
E. Tempel ◽  
M. Gramann ◽  
P. Nurmi ◽  
M. Haupt
Keyword(s):  
Dark Matter ◽  
Galaxy Cluster ◽  
Analytical Models ◽  
Matter Distribution ◽  
Galaxy Groups ◽  
The Galaxy ◽  
Dark Matter Distribution ◽  
Distribution Studies ◽  
The Universe ◽  
Good Agreement

AbstractThe SDSS galaxy catalog is one of the best databases for galaxy distribution studies. The SDSS DR8 data is used to construct the galaxy cluster catalog. We construct the clusters from the calculated luminosity density field and identify denser regions. Around these peak regions we construct galaxy clusters. Another interesting question in cosmology is how observable galaxy structures are connected to underlying dark matter distribution. To study this we compare the SDSS DR7 galaxy group catalog with galaxy groups obtained from the semi-analytical Millennium N-Body simulation. Specifically, we compare the group richness, virial radius, maximum separation and velocity dispersion distributions and find a relatively good agreement between the mock catalog and observations. This strongly supports the idea that the dark matter distribution and galaxies in the semi-analytical models and observations are very closely linked.

scholarly journals Constraining the abundance of dark matter in the central region of the galaxy cluster MACS J1206.2−0847 with a free-form strong lensing analysis

2020 ◽  
Vol 639 ◽  
pp. A125
Author(s):  
Alberto Manjón-García ◽  
Jose M. Diego ◽  
Diego Herranz ◽  
Daniel Lam
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Central Region ◽  
Total Mass ◽  
Galaxy Cluster ◽  
Free Form ◽  
Matter Distribution ◽  
Strong Lensing ◽  
The Galaxy ◽  
Dark Matter Distribution

We performed a free-form strong lensing analysis of the galaxy cluster MACS J1206.2−0847 in order to estimate and constrain its inner dark matter distribution. The free-form method estimates the cluster total mass distribution without using any prior information about the underlying mass. We used 97 multiple lensed images belonging to 27 background sources and derived several models, which are consistent with the data. Among these models, we focus on those that better reproduce the radial images that are closest to the centre of the cluster. These radial images are the best probes of the dark matter distribution in the central region and constrain the mass distribution down to distances ∼7 kpc from the centre. We find that the morphology of the innermost radial arcs is due to the elongated morphology of the dark matter halo. We estimate the stellar mass contribution of the brightest cluster galaxy and subtracted it from the total mass in order to quantify the amount of dark matter in the central region. We fitted the derived dark matter density profile with a gNFW, which is characterised by rs = 167 kpc, ρs = 6.7 × 106 M⊙ kpc−3, and γgNFW = 0.70. These results are consistent with a dynamically relaxed cluster. This inner slope is smaller than the cannonical γ = 1 predicted by standard CDM models. This slope does not favour self-interacting models for which a shallower slope would be expected.

scholarly journals Galaxy bias and σ8 from counts in cells from the SDSS main sample

2020 ◽  
Vol 498 (1) ◽  
pp. L125-L129 ◽  
Author(s):  
Andrew Repp ◽  
István Szapudi
Keyword(s):  
Dark Matter ◽  
Sloan Digital Sky Survey ◽  
Matter Distribution ◽  
Sky Survey ◽  
The Galaxy ◽  
Galaxy Sample ◽  
Dark Matter Distribution ◽  
Galaxy Bias ◽  
Previous Prescription ◽  
In Cells

ABSTRACT The counts-in-cells (CIC) galaxy probability distribution depends on both the dark matter clustering amplitude σ8 and the galaxy bias b. We present a theory for the CIC distribution based on a previous prescription of the underlying dark matter distribution and a linear volume transformation to redshift space. We show that, unlike the power spectrum, the CIC distribution breaks the degeneracy between σ8 and b on scales large enough that both bias and redshift distortions are still linear; thus, we obtain a simultaneous fit for both parameters. We first validate the technique on the Millennium Simulation and then apply it to the Sloan Digital Sky Survey main galaxy sample. We find σ8 = 0.92 ± .08 and $b = 1.39^{+.11}_{-.09}$ consistent with previous complementary results from redshift distortions and from Planck.

scholarly journals Visible Shapes of Black Holes M87* and SgrA*

Universe ◽  
2020 ◽  
Vol 6 (9) ◽  
pp. 154
Author(s):  
Vyacheslav I. Dokuchaev ◽  
Natalia O. Nazarova
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Milky Way ◽  
Dark Spot ◽  
Disk Model ◽  
Milky Way Galaxy ◽  
Supermassive Black Hole ◽  
The Galaxy ◽  
Visible Images ◽  
Inner Parts

We review the physical origins for possible visible images of the supermassive black hole M87* in the galaxy M87 and SgrA* in the Milky Way Galaxy. The classical dark black hole shadow of the maximal size is visible in the case of luminous background behind the black hole at the distance exceeding the so-called photon spheres. The notably smaller dark shadow (dark silhouette) of the black hole event horizon is visible if the black hole is highlighted by the inner parts of the luminous accreting matter inside the photon spheres. The first image of the supermassive black hole M87*, obtained by the Event Horizon Telescope collaboration, shows the lensed dark image of the southern hemisphere of the black hole event horizon globe, highlighted by accreting matter, while the classical black hole shadow is invisible at all. A size of the dark spot on the Event Horizon Telescope (EHT) image agrees with a corresponding size of the dark event horizon silhouette in a thin accretion disk model in the case of either the high or moderate value of the black hole spin, a≳0.75.

scholarly journals Tidal forces from the wake of dynamical friction: warps, lopsidedness, and kinematic misalignment

2020 ◽  
Vol 498 (1) ◽  
pp. 1080-1092
Author(s):  
Rain Kipper ◽  
María Benito ◽  
Peeter Tenjes ◽  
Elmo Tempel ◽  
Roberto de Propris
Keyword(s):  
Dark Matter ◽  
Velocity Dispersion ◽  
Position Angle ◽  
Back Reaction ◽  
Dynamical Friction ◽  
Matter Distribution ◽  
Tidal Forces ◽  
Isolated Galaxies ◽  
The Galaxy ◽  
Dark Matter Distribution

ABSTRACT A galaxy moving through a background of dark matter particles induces an overdensity of these particles or a wake behind it. The back reaction of this wake on the galaxy is a force field that can be decomposed into an effective deceleration (called dynamical friction) and a tidal field. In this paper, we determine the tidal forces, thus generated on the galaxy, and the resulting observables, which are shown to be warps, lopsidedness, and/or kinematic-photometric position angle misalignments. We estimate the magnitude of the tidal-like effects needed to reproduce the observed warp and lopsidedness on the isolated galaxy IC 2487. Within a realistic range of dark matter distribution properties, the observed, warped, and lopsided kinematical properties of IC 2487 are possible to reproduce (the background medium of dark matter particles has a velocity dispersion of $\lesssim 80\, {\rm km\, s^{-1}}$ and the density $10^4{\!-\!}10^5\, {\rm M_\odot \, kpc^{-3}}$, more likely at the lower end). We conclude that the proposed mechanism can generate warps, lopsidedness, and misalignments observed in isolated galaxies or galaxies in loose groups. The method can be used also to constrain dark matter spatial and velocity distribution properties.

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.

The LMC vs. the Milky Way

2019 ◽  
Vol 14 (S353) ◽  
pp. 123-127 ◽  
Author(s):  
Gurtina Besla ◽  
Nicolás Garavito-Camargo
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Dark Matter Halo ◽  
Matter Distribution ◽  
Structure And Dynamics ◽  
Gravitational Perturbations ◽  
Satellite Galaxy ◽  
Stellar Halo ◽  
Dark Matter Distribution

AbstractRecent advancements in astrometry and in cosmological models of dark matter halo growth have significantly changed our understanding of the dynamics of the Local Group. The most dramatic changes owe to a new picture of the structure and dynamics of the Milky Way’s most massive satellite galaxy, the Large Magellanic Cloud (LMC), which is most likely on its first passage about the Milky Way and ten times larger in mass than previously assumed. The LMC’s orbit through the Milky Way’s dark matter and stellar halo will leave characteristic signatures in both density and kinematics. Furthermore, the gravitational perturbations produced by both direct tidal forcing from the LMC and the response of the halo to its passage will together cause significant perturbations to the orbits of tracers of the Milky Way’s dark matter distribution. We advocate for the use of basis field expansion methods to fully capture and quantify these effects.

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