Existence of wormhole supported by the Einasto density profile

2018 ◽  
Vol 96 (11) ◽  
pp. 1242-1245
Author(s):  
Banashree Sen
Keyword(s):  
Density Profile ◽  
Galactic Halo ◽  
Rotational Velocity ◽  
Space Time ◽  
Velocity Curve ◽  
Density Model ◽  
Degree Polynomial ◽  
Traversable Wormhole

In this article, the existence of traversable wormhole in the outer and inner regions of the halos of galaxies using Einasto density profile has been investigated. We use Einasto density model, which is a 3D version of 2D Sérsic model (Dhar and Williams. M. Not. R. Astron. Soc. 405, 340 (2010). doi: 10.1111/j.1365-2966.2010.16446.x ). Two types of rotational velocity curve (one is a fifth degree polynomial and another is a constant) derived from experimental or observed data have been taken into account for describing the space–time of galactic halo comprising a traversable wormhole.

scholarly journals Direct Mapping of Massive Compact Objects in Extragalactic Dark Halos

2004 ◽  
Vol 220 ◽  
pp. 139-140
Author(s):  
Kaiki Taro Inoue ◽  
Masashi Chiba
Keyword(s):  
Spatial Distribution ◽  
High Resolution ◽  
Density Profile ◽  
Gravitational Lensing ◽  
Galactic Halo ◽  
Compact Objects ◽  
Multiple Images ◽  
Direct Mapping ◽  
Radio Map

We propose a method for directly detecting MASsive Compact Objects (MASCOs) in extragalactic halos, using VLBI techniques with extremely high resolution ˜ 0.01 milli-arcsec. If a galactic halo comprising a large number of MASCOs produces multiple images of a background radio-loud QSO by gravitational lensing, then a high-resolution radio map of each macro-lensed image should reveal microlensing effects by MASCOs. Based on the size, position, and magnified or demagnified patterns of images, we shall be able to determine the mass and density profile of an individual MASCO as well as its spatial distribution and abundance in a galactic halo.

scholarly journals The radial velocity dispersion profile of the Galactic halo: constraining the density profile of the dark halo of the Milky Way

2005 ◽  
Vol 364 (2) ◽  
pp. 433-442 ◽  
Author(s):  
Giuseppina Battaglia ◽  
Amina Helmi ◽  
Heather Morrison ◽  
Paul Harding ◽  
Edward W. Olszewski ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Density Profile ◽  
Milky Way ◽  
Velocity Dispersion ◽  
Galactic Halo ◽  
Dark Halo ◽  
Dispersion Profile

Charged perfect fluid dark matter model: Known mass density function approach

2021 ◽  
Vol 36 (07) ◽  
pp. 2150043
Author(s):  
Mithun Ghosh
Keyword(s):  
Dark Matter ◽  
Density Function ◽  
Perfect Fluid ◽  
Galactic Halo ◽  
Spiral Galaxies ◽  
Mass Density ◽  
Rotational Velocity ◽  
Cosmological Observations ◽  
Matter Model ◽  
Dark Matter Model

The concept of dark matter has been imported to explain the observed velocity profile of the spiral galaxies, the flat rotational velocity. Taking the flatness of rotation curves as an input and assuming that the galactic halo is filled with charged perfect fluid having known mass density function, we obtain a space time metric in the galactic halo region. The acquired solution indicates to a (nearly) flat universe, consistent with the present day cosmological observations. Various other aspects of the solution such as attractive gravity in the halo region, stability of the circular orbit, etc., are also analyzed.

scholarly journals THE STELLAR DENSITY PROFILE OF THE DISTANT GALACTIC HALO

2016 ◽  
Vol 832 (2) ◽  
pp. 206 ◽  
Author(s):  
Colin T. Slater ◽  
David L. Nidever ◽  
Jeffrey A. Munn ◽  
Eric F. Bell ◽  
Steven R. Majewski
Keyword(s):  
Density Profile ◽  
Galactic Halo ◽  
Stellar Density

Dark matter halo with charge in pseudo-spheroidal geometry

2021 ◽  
pp. 2150178
Author(s):  
Mithun Ghosh
Keyword(s):  
Dark Matter ◽  
Equation Of State ◽  
Perfect Fluid ◽  
Circular Orbit ◽  
Galactic Halo ◽  
Rotational Velocity ◽  
Dark Matter Halo ◽  
Cosmological Observations ◽  
The Stability ◽  
Spheroidal Geometry

The concept of dark matter (DM) hypothesis comes out as a result from the input of the observed flat rotational velocity. With the assumption that the galactic halo is pseudo-spheroidal and filled with charged perfect fluid, we have obtained a solution which has inkling to a (nearly) flat universe, compatible with the modern day cosmological observations. Various other important aspects of the solution such as attractive gravity in the halo region and the stability of the circular orbit are also explored. Also, the matter in the halo region satisfies the known equation of state which indicates its non-exotic nature.

scholarly journals The total stellar halo mass of the Milky Way

2019 ◽  
Vol 490 (3) ◽  
pp. 3426-3439 ◽  
Author(s):  
Alis J Deason ◽  
Vasily Belokurov ◽  
Jason L Sanders
Keyword(s):  
Density Profile ◽  
Galactic Halo ◽  
Mass Function ◽  
Initial Mass Function ◽  
Total Luminosity ◽  
Stellar Halo ◽  
Merger Event ◽  
Red Giant ◽  
Number Counts ◽  
Good Agreement

ABSTRACT We measure the total stellar halo luminosity using red giant branch (RGB) stars selected from Gaia data release 2. Using slices in magnitude, colour, and location on the sky, we decompose RGB stars belonging to the disc and halo by fitting two-dimensional Gaussians to the Galactic proper motion distributions. The number counts of RGB stars are converted to total stellar halo luminosity using a suite of isochrones weighted by age and metallicity, and by applying a volume correction based on the stellar halo density profile. Our method is tested and calibrated using Galaxia and N-body models. We find a total luminosity (out to 100 kpc) of $L_{\rm halo} = 7.9 \pm 2.0 \times 10^8\, \mathrm{L}_\odot$ excluding Sgr, and $L_{\rm halo} = 9.4 \pm 2.4 \times 10^8\, \mathrm{L}_\odot$ including Sgr. These values are appropriate for our adopted stellar halo density profile and metallicity distribution, but additional systematics related to these assumptions are quantified and discussed. Assuming a stellar mass-to-light ratio appropriate for a Kroupa initial mass function (M⋆/L = 1.5), we estimate a stellar halo mass of $M^\star _{\rm halo} = 1.4 \pm 0.4\times 10^9 \, \mathrm{M}_\odot$. This mass is larger than previous estimates in the literature, but is in good agreement with the emerging picture that the (inner) stellar halo is dominated by one massive dwarf progenitor. Finally, we argue that the combination of a ${\sim}10^9\, \mathrm{M}_\odot$ mass and an average metallicity of 〈[Fe/H]〉 ∼ −1.5 for the Galactic halo points to an ancient (∼10 Gyr) merger event.

scholarly journals Kinematics of the outer halo of M 87 as mapped by planetary nebulae

2018 ◽  
Vol 620 ◽  
pp. A111 ◽  
Author(s):  
A. Longobardi ◽  
M. Arnaboldi ◽  
O. Gerhard ◽  
C. Pulsoni ◽  
I. Söldner-Rembold
Keyword(s):  
Angular Momentum ◽  
Density Profile ◽  
Surface Density ◽  
Velocity Dispersion ◽  
Velocity Curve ◽  
Line Of Sight ◽  
X Ray ◽  
Dispersion Profile ◽  
Circular Velocity ◽  
Pn Velocity

Aims. We present a kinematic study of a sample of 298 planetary nebulas (PNs) in the outer halo of the central Virgo galaxy M 87 (NGC 4486). The line-of-sight velocities of these PNs are used to identify subcomponents, to measure the angular momentum content of the main M 87 halo, and to constrain the orbital distribution of the stars at these large radii. Methods. We use Gaussian mixture modelling to statistically separate distinct velocity components and identify the M 87 smooth halo component, its unrelaxed substructures, and the intra-cluster (IC) PNs. We compute probability weighted velocity and velocity dispersion maps for the smooth halo, and its specific angular momentum profile (λR) and velocity dispersion profile. Results. The classification of the PNs into smooth halo and ICPNs is supported by their different PN luminosity functions. Based on a Kolmogorov–Smirnov (K–S) test, we conclude that the ICPN line-of-sight velocity distribution (LOSVD) is consistent with the LOSVD of the galaxies in Virgo subcluster A. The surface density profile of the ICPNS at 100 kpc radii has a shallow logarithmic slope, −αICL ≃ −0.8, dominating the light at the largest radii. Previous B − V colour and resolved star metallicity data indicate masses for the ICPN progenitor galaxies of a few ×108 M⊙. The angular momentum-related λR profile for the smooth halo remains below 0.1, in the slow rotator regime, out to 135 kpc average ellipse radius (170 kpc major axis distance). Combining the PN velocity dispersion measurements for the M 87 halo with literature data in the central 15 kpc, we obtain a complete velocity dispersion profile out to Ravg = 135 kpc. The σhalo profile decreases from the central 400 km s−1 to about 270 km s−1 at 2–10 kpc, then rises again to ≃300 ± 50 km s−1 at 50–70 kpc, to finally decrease sharply to σhalo ∼ 100 km s−1 at Ravg = 135 kpc. The steeply decreasing outer σhalo profile and the surface density profile of the smooth halo can be reconciled with the circular velocity curve inferred from assuming hydrostatic equilibrium for the hot X-ray gas. Because this rises to νc,X ∼ km s−1 at 200 kpc, the orbit distribution of the smooth M 87 halo is required to change strongly from approximately isotropic within Ravg ∼ 60 kpc to very radially anisotropic at the largest distances probed. Conclusions. The extended LOSVD of the PNs in the M 87 halo allows the identification of several subcomponents: the ICPNs, the “crown” accretion event, and the smooth M 87 halo. In galaxies like M 87, the presence of these subcomponents needs to be taken into account to avoid systematic biases in estimating the total enclosed mass. The dynamical structure inferred from the velocity dispersion profile indicates that the smooth halo of M 87 steepens beyond Ravg = 60 kpc and becomes strongly radially anisotropic, and that the velocity dispersion profile is consistent with the X-ray circular velocity curve at these radii without non-thermal pressure effects.

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