scholarly journals Segmenting the Universe into dynamically coherent basins

2020 ◽  
Vol 493 (3) ◽  
pp. 3513-3520
Author(s):  
Alexandra Dupuy ◽  
Hélène M Courtois ◽  
Noam I Libeskind ◽  
Daniel Guinet
Keyword(s):  
Large Scale ◽  
Basins Of Attraction ◽  
Data Set ◽  
Density Profiles ◽  
Large Scale Structures ◽  
Unique Definition ◽  
Scale Structures ◽  
Definition Of ◽  
Previous Letter ◽  
The Universe

ABSTRACT This paper explores in depth a watershed concept to partition the Universe, introduced in a previous Letter and applied to the Cosmicflows-3 observational data set. We present a series of tests conducted with cosmological dark matter simulations. In particular, we are interested in quantifying the evolution with redshift of large-scale structures when defined as segmented basins of attraction. This new dynamical definition in the field of measuring standard rulers demonstrates robustness since all basins show a density contrast δ above 1 (mean Universe density) independently of the simulation spatial resolution or the redshift. Another major finding is that density profiles of the basins show universality in slope. Consequently, there is a unique definition of what is a gravitational watershed at a large scale, which can be further used as a probe for cosmology studies.

scholarly journals Large-Scale Structure in the Universe: Spatial Distribution and Peculiar Velocities

1987 ◽  
Vol 124 ◽  
pp. 335-348
Author(s):  
Neta A. Bahcall
Keyword(s):  
Dark Matter ◽  
Spatial Distribution ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Clusters Of Galaxies ◽  
Large Scale Structures ◽  
Peculiar Velocities ◽  
Scale Structures ◽  
The Universe

The evidence for the existence of very large scale structures, ∼ 100h−1Mpc in size, as derived from the spatial distribution of clusters of galaxies is summarized. Detection of a ∼ 2000 kms−1 elongation in the redshift direction in the distribution of the clusters is also described. Possible causes of the effect are peculiar velocities of clusters on scales of 10–100h−1Mpc and geometrical elongation of superclusters. If the effect is entirely due to the peculiar velocities of clusters, then superclusters have masses of order 1016.5M⊙ and may contain a larger amount of dark matter than previously anticipated.

Two types of voids and super-large scale structures in the universe?

1994 ◽  
Vol 5 (1-4) ◽  
pp. 75-79 ◽  
Author(s):  
S. A. Pustil'nik ◽  
A. V. Ugryumov ◽  
V. A. Lipovetsky
Keyword(s):  
Large Scale ◽  
Large Scale Structures ◽  
Scale Structures ◽  
The Universe

scholarly journals Multiscaling and nonextensivity of large-scale structures in the Universe

2002 ◽  
Vol 168-169 ◽  
pp. 404-409 ◽  
Author(s):  
F.M Ramos ◽  
C.A Wuensche ◽  
A.L.B Ribeiro ◽  
R.R Rosa
Keyword(s):  
Large Scale ◽  
Large Scale Structures ◽  
Scale Structures ◽  
The Universe

scholarly journals Large-scale structure probes of modified gravity

2018 ◽  
Vol 27 (15) ◽  
pp. 1848005 ◽  
Author(s):  
Catherine Heymans ◽  
Gong-Bo Zhao
Keyword(s):  
Gravitational Lensing ◽  
Modified Gravity ◽  
Large Scale ◽  
Information Gain ◽  
Einstein Gravity ◽  
Large Scale Structures ◽  
Modified Gravity Theories ◽  
Scale Structures ◽  
The Impact ◽  
The Universe

Observations of the evolution of large-scale structures in the Universe provides unique tools to confront Einstein’s theory of General Relativity on cosmological scales. We review weak gravitational lensing and galaxy clustering studies, discussing how these can be used in combination in order to constrain a range of different modified gravity theories. We argue that in order to maximise the future information gain from these probes, theoretical effort will be required in order to model the impact of beyond-Einstein gravity in the nonlinear regime of structure formation.

scholarly journals Deep learning for Sunyaev–Zel’dovich detection in Planck

2020 ◽  
Vol 634 ◽  
pp. A81
Author(s):  
V. Bonjean
Keyword(s):  
Deep Learning ◽  
Galaxy Clusters ◽  
Large Scale ◽  
Galaxy Cluster ◽  
Proof Of Concept ◽  
Microwave Background ◽  
Large Scale Structures ◽  
Hot Gas ◽  
Scale Structures ◽  
The Universe

The Planck collaboration has extensively used the six Planck HFI frequency maps to detect the Sunyaev–Zel’dovich (SZ) effect with dedicated methods, for example by applying (i) component separation to construct a full-sky map of the y parameter or (ii) matched multi-filters to detect galaxy clusters via their hot gas. Although powerful, these methods may still introduce biases in the detection of the sources or in the reconstruction of the SZ signal due to prior knowledge (e.g. the use of the generalised Navarro, Frenk, and White profile model as a proxy for the shape of galaxy clusters, which is accurate on average but not for individual clusters). In this study, we use deep learning algorithms, more specifically, a U-net architecture network, to detect the SZ signal from the Planck HFI frequency maps. The U-net shows very good performance, recovering the Planck clusters in a test area. In the full sky, Planck clusters are also recovered, together with more than 18 000 other potential SZ sources for which we have statistical indications of galaxy cluster signatures, by stacking at their positions several full-sky maps at different wavelengths (i.e. the cosmic microwave background lensing map from Planck, maps of galaxy over-densities, and the ROSAT X-ray map). The diffuse SZ emission is also recovered around known large-scale structures such as Shapley, A399–A401, Coma, and Leo. Results shown in this proof-of-concept study are promising for potential future detection of galaxy clusters with low SZ pressure with this kind of approach, and more generally, for potential identification and characterisation of large-scale structures of the Universe via their hot gas.

scholarly journals X-Ray Large Scale Structure and XMM

1998 ◽  
Vol 188 ◽  
pp. 177-180
Author(s):  
M. Pierre
Keyword(s):  
Large Scale ◽  
Initial Conditions ◽  
Data Set ◽  
X Ray ◽  
Large Scale Structures ◽  
The Galaxy ◽  
Optical Wavelengths ◽  
Analytical Approaches ◽  
The Universe ◽  
Additional Constraints

The formation of Large Scale Structures (LSS) in the universe was first studied at optical wavelengths as the galaxy spatial distribution appeared to be far from homogeneous. Considerable effort has been invested in semi-analytical approaches and in numerical simulations (DM + hot gas) to explain the observed structures, given some set of initial conditions and using additional constraints provided by the COBE results. It is now clear however, that these two extreme data set are not sufficient to discriminate between the possible remaining cosmological scenarios. It is thus timely to investigate LSS at a much higher redshift than the present survey limits both in the optical and in other wavebands. In this context, the X-ray band will certainly become a hot field with the advent of the XMM observatory. The next section briefly summarizes what is known about LSS from optical wavelengths and simulations. Sect. 3 reviews the particular points that can be addressed in the X-ray band. Last section presents realistic prospects for mapping LSS with XMM.

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