scholarly journals Testing gravity using galaxy-galaxy lensing and clustering amplitudes in KiDS-1000, BOSS, and 2dFLenS

2020 ◽  
Vol 642 ◽  
pp. A158 ◽  
Author(s):  
Chris Blake ◽  
Alexandra Amon ◽  
Marika Asgari ◽  
Maciej Bilicki ◽  
Andrej Dvornik ◽  
...  
Keyword(s):  
General Relativity ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Amplitude Ratio ◽  
Matter Density ◽  
Ratio Test ◽  
Theoretical Expectation ◽  
Background Light ◽  
Photometric Redshift ◽  
Redshift Surveys

The physics of gravity on cosmological scales affects both the rate of assembly of large-scale structure and the gravitational lensing of background light through this cosmic web. By comparing the amplitude of these different observational signatures, we can construct tests that can distinguish general relativity from its potential modifications. We used the latest weak gravitational lensing dataset from the Kilo-Degree Survey, KiDS-1000, in conjunction with overlapping galaxy spectroscopic redshift surveys, BOSS and 2dFLenS, to perform the most precise existing amplitude-ratio test. We measured the associated EG statistic with 15 − 20% errors in five Δz = 0.1 tomographic redshift bins in the range 0.2 <  z <  0.7 on projected scales up to 100 h−1 Mpc. The scale-independence and redshift-dependence of these measurements are consistent with the theoretical expectation of general relativity in a Universe with matter density Ωm = 0.27 ± 0.04. We demonstrate that our results are robust against different analysis choices, including schemes for correcting the effects of source photometric redshift errors, and we compare the performance of angular and projected galaxy-galaxy lensing statistics.

scholarly journals Testing Gravity using Void Profiles

2014 ◽  
Vol 11 (S308) ◽  
pp. 555-560 ◽  
Author(s):  
Yan-Chuan Cai ◽  
Nelson Padilla ◽  
Baojiu Li
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Modified Gravity ◽  
Large Scale ◽  
Line Of Sight ◽  
Number Density ◽  
Density Profiles ◽  
Photometric Redshift ◽  
Redshift Survey ◽  
Near Future

AbstractWe investigate void properties inf(R)models using N-body simulations, focusing on their differences from General Relativity (GR) and their detectability. In the Hu-Sawickif(R)modified gravity (MG) models, the halo number density profiles of voids are not distinguishable from GR. In contrast, the samef(R)voids are more empty of dark matter, and their profiles are steeper. This can in principle be observed by weak gravitational lensing of voids, for which the combination of a spectroscopic redshift and a lensing photometric redshift survey over the same sky is required. Neglecting the lensing shape noise, thef(R)model parameter amplitudesfR0=10-5and 10-4may be distinguished from GR using the lensing tangential shear signal around voids by 4 and 8 σ for a volume of 1 (Gpc/h)3. The line-of-sight projection of large-scale structure is the main systematics that limits the significance of this signal for the near future wide angle and deep lensing surveys. For this reason, it is challenging to distinguishfR0=10-6from GR. We expect that this can be overcome with larger volume. The halo void abundance being smaller and the steepening of dark matter void profiles inf(R)models are unique features that can be combined to break the degeneracy betweenfR0and σ8.

scholarly journals Probing the dark matter density evolution law with large scale structures

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Kamal Bora ◽  
R. F. L. Holanda ◽  
Shantanu Desai
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Galaxy Cluster ◽  
Matter Density ◽  
Evolution Law ◽  
Large Scale Structures ◽  
Dark Matter Density ◽  
Scale Structures ◽  
Rule Out

AbstractWe propose a new method to explore a possible departure from the standard time evolution law for the dark matter density. We looked for a violation of this law by using a deformed evolution law, given by $$\rho _c(z) \propto (1+z)^{3+\epsilon }$$ ρ c ( z ) ∝ ( 1 + z ) 3 + ϵ , and then constrain $$\epsilon $$ ϵ . The dataset used for this purpose consists of Strong Gravitational Lensing data obtained from SLOAN Lens ACS, BOSS Emission-line Lens Survey, Strong Legacy Survey SL2S, and SLACS; along with galaxy cluster X-ray gas mass fraction measurements obtained using the Chandra Telescope. Our analyses show that $$\epsilon $$ ϵ is consistent with zero within 1 $$\sigma $$ σ c.l., but the current dataset cannot rule out with high confidence level interacting models of dark matter and dark energy.

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.

scholarly journals A gravitational puzzle

2011 ◽  
Vol 369 (1957) ◽  
pp. 4998-5002
Author(s):  
Robert R. Caldwell
Keyword(s):  
Gravitational Lensing ◽  
Large Scale ◽  
Current Data ◽  
Cosmic Acceleration ◽  
Late Time ◽  
Microwave Background ◽  
Scale Free ◽  
Cosmological Observations ◽  
Stress Energy ◽  
The Relationship

The challenge to understand the physical origin of the cosmic acceleration is framed as a problem of gravitation. Specifically, does the relationship between stress–energy and space–time curvature differ on large scales from the predictions of general relativity. In this article, we describe efforts to model and test a generalized relationship between the matter and the metric using cosmological observations. Late-time tracers of large-scale structure, including the cosmic microwave background, weak gravitational lensing, and clustering are shown to provide good tests of the proposed solution. Current data are very close to proving a critical test, leaving only a small window in parameter space in the case that the generalized relationship is scale free above galactic scales.

scholarly journals Observational challenges for the standard FLRW model

2016 ◽  
Vol 25 (03) ◽  
pp. 1630007 ◽  
Author(s):  
Thomas Buchert ◽  
Alan A. Coley ◽  
Hagen Kleinert ◽  
Boudewijn F. Roukema ◽  
David L. Wiltshire
Keyword(s):  
General Relativity ◽  
Cosmological Model ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Parallel Session

In this paper, we summarize some of the main observational challenges for the standard Friedmann–Lemaître–Robertson–Walker (FLRW) cosmological model and describe how results recently presented in the parallel session “Large-scale Structure and Statistics” (DE3) at the “Fourteenth Marcel Grossman Meeting on General Relativity” are related to these challenges.

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