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Updated: May 28, 2025
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The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
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Challenges to the standard cosmological model from large-scale bulk flow estimates
1Department of Physics, Willamette University, Salem, OR 97301, USA.
Summary
Galaxy motions show a large-scale bulk flow that challenges the standard cosmological model. This bulk flow
Area of Science:
- Cosmology
- Astrophysics
- Large-scale structure of the Universe
Background:
- The cosmological principle posits that galaxy motions should be small on large scales.
- Anomalous large-scale bulk flows have been hinted at for decades, but data quality has limited constraints.
- Peculiar velocity data, like that from CosmicFlows-4, now allow for meaningful tests of cosmological models.
Purpose of the Study:
- To test the cosmological principle and the standard cosmological model.
- To investigate the behavior of large-scale bulk flow with increasing volume.
- To identify potential origins of observed anomalous bulk flows.
Main Methods:
- Utilized the minimum variance (MV) method to estimate bulk flow.
- Employed data from the CosmicFlows-4 (CF4) catalogue.
- Analyzed bulk flow in volumes of increasing radii.
Main Results:
- The amplitude of the bulk flow was found to increase with the radius of the volume analyzed.
- A significant bulk flow was detected at a radius of [Formula: see text] Mpc.
- This observed bulk flow has a low probability (0.003%) of occurring within the standard cosmological model.
Conclusions:
- The findings challenge the standard cosmological model and the cosmological principle.
- The increasing bulk flow amplitude with radius suggests a deviation from expected cosmological behavior.
- Further investigation into the characteristics and origin of this large-scale bulk flow is warranted.
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