scholarly journals Performance study of Lagrangian methods: reconstruction of large scale peculiar velocities and baryonic acoustic oscillations

2017 ◽  
pp. stx152 ◽  
Author(s):  
J. A. Keselman ◽  
A. Nusser
Keyword(s):  
Large Scale ◽  
Acoustic Oscillations ◽  
Performance Study ◽  
Lagrangian Methods ◽  
Peculiar Velocities ◽  
Baryonic Acoustic Oscillations

scholarly journals Large-scale structure studies with AGN in the eROSITA/SRG All-Sky Survey

2013 ◽  
Vol 9 (S304) ◽  
pp. 422-425
Author(s):  
Alexander Kolodzig ◽  
Marat Gilfanov ◽  
Gert Hütsi ◽  
Rashid Sunyaev
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Full Potential ◽  
Acoustic Oscillations ◽  
X Ray ◽  
Bias Factor ◽  
Sky Survey ◽  
First Time ◽  
Baryonic Acoustic Oscillations

AbstractThe four-year X-ray all-sky survey (eRASS) of the eROSITA telescope aboard the Spektrum-Roentgen-Gamma satellite will detect ~ 3 million active galactic nuclei (AGN) with a median redshift of z≈1. We show that this unprecedented AGN sample, complemented with redshift information, will supply us with outstanding opportunities for large-scale structure research. For the first time with a sample of X-ray selected AGN, it will become possible to perform detailed redshift- and luminosity-resolved studies of the linear bias factor, and to convincingly detected baryonic acoustic oscillations (BAOs). To exploit the full potential of the eRASS AGN sample, photometric and spectroscopic surveys of large areas and a sufficient depth will be needed.

Large‐Scale Power Spectrum and Cosmological Parameters from SFI Peculiar Velocities

1999 ◽  
Vol 523 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Wolfram Freudling ◽  
Idit Zehavi ◽  
Luiz N. da Costa ◽  
Avishai Dekel ◽  
Amiram Eldar ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Peculiar Velocities

scholarly journals Large-Scale Flows in the Local Universe

1996 ◽  
Vol 168 ◽  
pp. 175-182 ◽  
Author(s):  
D.S. Mathewson ◽  
V.L. Ford
Keyword(s):  
Large Scale ◽  
Velocity Measurements ◽  
Local Universe ◽  
Peculiar Velocities ◽  
Redshift Surveys ◽  
Density Maps ◽  
The Universe ◽  
Great Wall ◽  
Great Attractor ◽  
Streaming Flow

Peculiar velocity measurements of 2500 southern spiral galaxies show large-scale flows in the direction of the Hydra-Centaurus clusters which fully participate in the flow themselves. The flow is not uniform over this region and seems to be associated with the denser regions which participate in the flow of amplitude about 400km/s. In the less dense regions the flow is small or non-existent. This makes the flow quite asymmetric and inconsistent with that expected from large-scale, parallel streaming flow that includes all galaxies out to 6000km/s as previously thought. The flow cannot be modelled by a Great Attractor at 4300km/s or the Centaurus clusters at 3500km/s. Indeed, from the density maps derived from the redshift surveys of “optical” and IRAS galaxies, it is difficult to see how the mass concentrations can be responsible particularly as they themselves participate in the flow. These results bring into question the generally accepted reason for the peculiar velocities of galaxies that they arise solely as a consequence of infall into the dense regions of the universe. To the N. of the Great Attractor region, the flow increases and shows no sign of diminishing out to the redshift limit of 8000km/s in this direction. We may have detected flow in the nearest section of the Great Wall.

An Early Performance Study of Large-Scale POWER8 SMP Systems

2016 ◽  
Author(s):  
Xing Liu ◽  
Daniele Buono ◽  
Fabio Checconi ◽  
Jee W. Choi ◽  
Xinyu Que ◽  
...  
Keyword(s):  
Large Scale ◽  
Performance Study ◽  
Early Performance

Performance Study of Large Scale Network Slice Deployment in a 5G Core Testbed

2021 ◽  
Author(s):  
Shwetha Vittal ◽  
Aditya Chilukuri ◽  
Sourav Sarkar ◽  
Akshitha Shinde ◽  
Antony Franklin A
Keyword(s):  
Large Scale ◽  
Performance Study ◽  
Large Scale Network ◽  
Scale Network

Design and performance study on a large-scale hybrid CPV/T system based on unsteady-state thermal model

Solar Energy ◽  
2019 ◽  
Vol 177 ◽  
pp. 427-439 ◽  
Author(s):  
Zexin Wang ◽  
Jinjia Wei ◽  
Gaoming Zhang ◽  
Huling Xie ◽  
Muhammad Khalid
Keyword(s):  
Thermal Model ◽  
Large Scale ◽  
Unsteady State ◽  
Performance Study ◽  
And Performance ◽  
T System

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 Anti-symmetric clustering signals in the observed power spectrum

2021 ◽  
Vol 2021 (12) ◽  
pp. 003
Author(s):  
José Fonseca ◽  
Chris Clarkson
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Euler Equation ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Power Spectra ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Signal To Noise ◽  
Peculiar Velocities

Abstract In this paper, we study how to directly measure the effect of peculiar velocities in the observed angular power spectra. We do this by constructing a new anti-symmetric estimator of Large Scale Structure using different dark matter tracers. We show that the Doppler term is the major component of our estimator and we show that we can measure it with a signal-to-noise ratio up to ∼ 50 using a futuristic SKAO HI galaxy survey. We demonstrate the utility of this estimator by using it to provide constraints on the Euler equation.

scholarly journals Do supernovae indicate an accelerating universe?

2021 ◽  
Author(s):  
Roya Mohayaee ◽  
Mohamed Rameez ◽  
Subir Sarkar
Keyword(s):  
Dark Energy ◽  
Large Scale ◽  
Bulk Flow ◽  
Expansion Rate ◽  
Accelerated Expansion ◽  
Accelerating Universe ◽  
Acoustic Oscillations ◽  
Independent Evidence ◽  
Peculiar Velocity ◽  
Hubble Expansion

AbstractIn the late 1990’s, observations of two directionally-skewed samples of, in total, 93 Type Ia supernovae were analysed in the framework of the Friedmann–Lemaître–Robertson–Walker (FLRW) cosmology. Assuming these to be ‘standard(isable) candles’ it was inferred that the Hubble expansion rate is accelerating as if driven by a positive Cosmological Constant $$\varLambda $$ Λ in Einstein’s theory of gravity. This is still the only direct evidence for the ‘dark energy’ that is the dominant component of today’s standard $$\varLambda $$ Λ CDM cosmological model. Other data such as baryon acoustic oscillations (BAO) in the large-scale distribution of galaxies, temperature fluctuations in the cosmic microwave background (CMB), measurement of stellar ages, the rate of growth of structure, etc are all ‘concordant’ with this model but do not provide independent evidence for accelerated expansion. The recent discussions about whether the inferred acceleration is real rests on analysis of a larger sample of 740 SNe Ia which shows that these are not quite standard candles, and more importantly highlights the ‘corrections’ that are applied to analyse the data in the FLRW framework. The latter holds in the reference frame in which the CMB is isotropic, whereas observations are carried out in our heliocentric frame in which the CMB has a large dipole anisotropy. This is assumed to be of kinematic origin i.e. due to our non-Hubble motion driven by local inhomogeneity in the matter distribution which has grown under gravity from primordial density perturbations traced by the CMB fluctuations. The $$\varLambda $$ Λ CDM model predicts how this peculiar velocity should fall off as the averaging scale is raised and the universe becomes sensibly homogeneous. However observations of the local ‘bulk flow’ are inconsistent with this expectation and convergence to the CMB frame is not seen. Moreover, the kinematic interpretation implies a corresponding dipole in the sky distribution of high redshift quasars, which is rejected by observations at $$4.9\sigma $$ 4.9 σ . Hence the peculiar velocity corrections employed in supernova cosmology are inconsistent and discontinuous within the data. The acceleration of the Hubble expansion rate is in fact anisotropic at $$3.9\sigma $$ 3.9 σ and aligned with the bulk flow. Thus dark energy could be an artefact of analysing data assuming that we are idealised observers in an FLRW universe, when in fact the real universe is inhomogeneous and anisotropic out to distances large enough to impact on cosmological analyses.

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