scholarly journals The Universe Behind the Southern Milky Way

2005 ◽  
Vol 216 ◽  
pp. 203-210 ◽  
Author(s):  
Renée C. Kraan-Korteweg ◽  
Lister Staveley-Smith ◽  
Jennifer Donley ◽  
Bärbel Koribalski ◽  
Patricia A. Henning
Keyword(s):  
Surface Brightness ◽  
Large Scale ◽  
High Surface ◽  
Star Forming ◽  
Large Scale Structures ◽  
The North ◽  
Low Surface Brightness ◽  
Scale Structures ◽  
Zone Of Avoidance ◽  
The Universe

A first analysis of a deep blind HI survey covering the southern Zone of Avoidance plus an extension towards the north (196† ≤ ℓ ≤ 52†) obtained with the Multibeam receiver at the 64-m Parkes telescope reveals slightly over a thousand galaxies within the latitude completeness limit of |b| ≤ 5†. The characteristics and the uncovered large-scale structures of this survey are described, in particular the prominence of the Norma Supercluster, the possible cluster around PKS 1343–601 (both in the Great Attractor region), as well as the Local Void and the clustering in the Puppis region. In this blind HI survey HIZOA J0836–43 was discovered, one of the most massive spiral galaxies known to date (MHI = 7.3 × 1010 M⊙, MT = 1.1 × 1012 M⊙; H0 = 75 km/s/Mpc). Although of similar mass to Malin 1-like objects, this galaxy does not share their typical low-surface brightness properties, but seems an exceptionally massive but normal, high surface brightness, star-forming galaxy.

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.

scholarly journals Exploring the origin of ultra-diffuse galaxies in clusters from their primordial alignment

2020 ◽  
Vol 498 (1) ◽  
pp. L72-L76 ◽  
Author(s):  
Yu Rong ◽  
Pavel E Mancera Piña ◽  
Elmo Tempel ◽  
Thomas H Puzia ◽  
Sven De Rijcke
Keyword(s):  
Large Scale ◽  
High Surface ◽  
Outer Region ◽  
Major Axis ◽  
Large Scale Structures ◽  
Tidal Interactions ◽  
Angular Momenta ◽  
Cluster Environment ◽  
Scale Structures ◽  
Absolute Magnitudes

ABSTRACT We find that the minor axes of the ultra-diffuse galaxies (UDGs) in Abell 2634 tend to be aligned with the major axis of the central dominant galaxy, at a $\gtrsim 95{{\ \rm per\ cent}}$ confidence level. This alignment is produced by the bright UDGs with the absolute magnitudes Mr < −15.3 mag, and outer-region UDGs with R > 0.5R200. The alignment signal implies that these bright, outer-region UDGs are very likely to acquire their angular momenta from the vortices around the large-scale filament before they were accreted into A2634, and form their extended stellar bodies outside of the cluster; in this scenario, the orientations of their primordial angular momenta, which are roughly shown by their minor axes on the images, should tend to be parallel to the elongation of the large-scale filament. When these UDGs fell into the unrelaxed cluster A2634 along the filament, they could still preserve their primordial alignment signal before violent relaxation and encounters. These bright, outer-region UDGs in A2634 are very unlikely to be the descendants of the high-surface-brightness dwarf progenitors under tidal interactions with the central dominant galaxy in the cluster environment. Our results indicate that the primordial alignment could be a useful probe of the origin of UDGs in large-scale structures.

scholarly journals HI Searches in the Zone of Avoidance: Past and Present (and Future)

1997 ◽  
Vol 14 (1) ◽  
pp. 21-24 ◽  
Author(s):  
P. A. Henning
Keyword(s):  
Feasibility Study ◽  
Surface Brightness ◽  
The South ◽  
The North ◽  
Low Surface Brightness ◽  
Complete Survey ◽  
Zone Of Avoidance ◽  
Low Surface Brightness Galaxies

AbstractIn the regions of highest optical obscuration and infrared confusion, only 21-cm emission can be used to find galaxies in the Zone of Avoidance. A feasibility study conducted with the 300-ft telescope successfully uncovered galaxies which seem to be consistent with populations of optically-selected low surface brightness galaxies. A complete survey is currently being conducted in the north with the Dwingeloo telescope. The big breakthrough should come in the south, however, with the advent of the Parkes telescope multibeam system.

scholarly journals Early Results from the VIMOS VLT Deep Survey

2005 ◽  
Vol 216 ◽  
pp. 381-389
Author(s):  
O. Le Fèvre ◽  
C. Adami ◽  
O. Ilbert ◽  
V. Le Brun ◽  
C. Marinoni ◽  
...  
Keyword(s):  
Large Scale ◽  
Limited Sample ◽  
Redshift Distribution ◽  
Star Forming ◽  
Large Scale Structures ◽  
Early Results ◽  
Main Challenge ◽  
Deep Survey ◽  
Scale Structures ◽  
First Time

The VIMOS VLT Deep Survey (VVDS) is underway to study the evolution of galaxies, large scale structures and AGNs, from the measurement of more than 100 000 spectra of faint objects. We present here the results from the first epoch observations of more than 20000 spectra. The main challenge of the program, the redshift measurements, is described, in particular entering the “redshift desert” in the range 1.5 < z < 3 for which only very weak features are detected in the observed wavelength range. The redshift distribution of a magnitude limited sample brighter than IAB = 24 is presented for the first time, showing a peak at a low redshift z ∼ 0.7, and a tail extending all the way above z = 4. The evolution of the luminosity function out to z = 1.5 is presented, with the LF of blue star forming galaxies carrying most of the evolution, with L* changing by more than two magnitudes for this sub-sample.

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.

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