The cosmic web for density perturbations of various scales (original) (raw)
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The impact of the connectivity of the cosmic web on the physical properties of galaxies at its nodes
Monthly Notices of the Royal Astronomical Society
We investigate the impact of the number of filaments connected to the nodes of the cosmic web on the physical properties of their galaxies using the Sloan Digital Sky Survey. We compare these measurements to the cosmological hydrodynamical simulations H orizon-(no)AGN and Simba. We find that more massive galaxies are more connected, in qualitative agreement with theoretical predictions and measurements in dark-matter-only simulations. The star formation activity and morphology of observed galaxies both display some dependence on the connectivity of the cosmic web at a fixed stellar mass: Less star forming and less rotation supported galaxies also tend to have higher connectivity. These results qualitatively hold both for observed and for virtual galaxies, and can be understood given that the cosmic web is the main source of fuel for galaxy growth. The simulations show the same trends at a fixed halo mass, suggesting that the geometry of filamentary infall impacts galaxy properties b...
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The clustering of critical points in the evolving cosmic web
arXiv: Cosmology and Nongalactic Astrophysics, 2020
Focusing on both small separations and Baryonic Acoustic Oscillation scales, the cosmic evolution of the clustering properties of peak, void, wall, and filament-type critical points is measured using two-point correlation functions in Lambda\LambdaLambdaCDM dark matter simulations as a function of their relative rarity. A qualitative comparison to the corresponding theory for Gaussian Random fields allows us to understand the following observed features: i) the appearance of an exclusion zone at small separation, whose size depends both on rarity and on the signature (\ie the number of negative eigenvalues) of the critical points involved; ii) the amplification of the Baryonic Acoustic Oscillation bump with rarity and its reversal for cross-correlations involving negatively biased critical points; iii) the orientation-dependent small-separation divergence of the cross-correlations of peaks and filaments (voids and walls) which reflects the relative loci of such points in the filament's (w...
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Dark Matter and the Cosmic Web revised.pdf
The cosmic web is a filament like structure that connects galaxies. It is imaged by gravitational lensing and is thought to be composed mainly of dark matter since it is very faint in the electromagnetic spectrum. There are computer simulations of the web showing that galaxies are often nodes for multiple branches. https://www.youtube.com/watch?v=ivymdduulFU . Conversely there are volumes in the sky that are relatively devoid of matter. However, cosmologists have long recognized that mass is uniform [18][21] at a scale much larger than the web. Scientists are trying to understand dark matter and dark energy [20]. The unexpected web like structure adds to a list of cosmology unknowns. The author studied mass accumulation [16] with an expansion model associated with energy values and relationships found in the proton model [Appendix 1]. WMAP [17][19] and later the PLANCK satellites measured cosmic background radiation anisotropy and concluded that there are scale invariant density variations on the order of d’/d=8e-6. The author used this data to predict mass accumulation in three primary levels of structure. It appears that stars, within galaxies within galaxy clusters all result from differential central mass related to measured density variations. Surrounding density is accelerated toward the central mass and densified by radius reduction that obeys a R*v^2=r*V^2 conservation law. Simulations presented agree with several observations including when stars light up, the orbital velocity of stars and Hubble’s constant [15]. This paper takes the simulations one step further by studying the shape of the structure. This paper provides a reasonable explanation for the cosmic web without assuming dark matter [8][12]. Falling mass develops a preferred orientation that changes the shape of the mass, lengthening it into filaments rather than spheres. This is like our atmosphere that forms tornados when there are density differences. In this case, the density difference is the central mass of the star volume. As mass falls toward the central density, it contracts and spins extending the filament outward from the central mass. Simulations of these structures extend between mass accumulating in adjacent areas and appear to be the feature being imaged as the cosmic web. A realistic looking simulation of a barred spiral galaxy is included.
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