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“STRUCTURE formation happens hierarchically, and real DM halos haven’t reached a steady state. They contain substructure in the form of subhalos and tidal streams, and the velocity distribution contains imprints of the halo’s assembly history.” (DM = dark matter). https://lnkd.in/e6ifiQMn View in LinkedIn

EQUILIBRIUM. “Collisionless particles can change their energy and reach a steady state if they experience a fluctuating gravitational potential (a process known as ‘violent relation’).” https://lnkd.in/e6ifiQMn View in LinkedIn

ELEPHANT IN THE ROOM. “If we want to confirm the existence of DM (and the standard ΛCDM cosmological model) we need to detect it. The signatures expected in DM detection experiments depend on how it’s distributed.” (DM = dark matter; ΛCDM = Lambda cold dark matter). https://lnkd.in/e6ifiQMn View in LinkedIn

ASTROPHYSICS GAP. “Explaining all of the diverse observations discussed above, on scales ranging from individual galaxies to the Universe as a whole is, however, a major challenge.” https://lnkd.in/e6ifiQMn View in LinkedIn

NEW LAWS OF PHYSICS? “While Newton’s laws have been tested to high accuracy on terrestrial scales, the laws of gravity could, in principle, be different on astronomical/cosmological scales.” https://lnkd.in/e6ifiQMn View in LinkedIn

This is where the next generation places its hope. View in LinkedIn

NEVER FORGET THIS. “Another major drawback of the Standard Model is the fact that it uses two predominant components, dark matter and dark energy, supposed to represent about 95% of the universe energy density, but which have remarkably resisted to experimental identification so far.” https://lnkd.in/daA2SgMy View in LinkedIn

THE KEY. “All of the observational evidence for DM to date comes from its gravitational effects. Therefore it’s not unreasonable to ask whether the observations could instead be explained by modifying the laws of gravity.” (DM = dark matter). https://lnkd.in/e6ifiQMn View in LinkedIn

INDIRECT SENSING. “Large scale structure observations are typically not as powerful or clean a probe of cosmological parameters on their own as the CMB anisotropies are (galaxies are biased tracers of the matter distribution, redshift is a combination of expansion and peculiar velocity etc.).” (CMB = cosmic microwave background). https://lnkd.in/e6ifiQMn View in LinkedIn

FLAT GEOMETRY. “The positions of the acoustic peaks in the CMB angular power spectrum (or equivalently the typical size of the hot/cold spots) are largely sensitive to the geometry of the Universe, and hence the total energy. i.e. the total energy density is very close to the critical density for which the geometry of the universe is flat.” (CMB = cosmic microwave background). https://lnkd.in/e6ifiQMn View in LinkedIn