It turns out that dark matter (opens in new tab) forms smaller "clumps" than scientists thought, confirming a fundamental prediction about the mysterious substance.
Dark matter is the invisible stuff that is said to make up about 27% of all of the mass in the universe. Though researchers cannot directly observe dark matter because it doesn't emit light or energy, scientists think it dominates all of outer space — and even Earth.
It may sound weird, but dark matter gets "clumpy."
According to the widely accepted "cold dark matter" theory, all galaxies form within clouds of dark matter, which is made up of slow-moving, or "cold," particles. These "cold" dark matter particles form structures, or "clumps," that can be as "small" as an airplane or as massive as hundreds of thousands of Milky Way galaxies, according to a NASA statement (opens in new tab).
Related: Vera Rubin: The Astronomer Who Brought Dark Matter to Light (opens in new tab)
Now, a recent study, which used a new observation technique with NASA's Hubble Space Telescope (opens in new tab), provides incredible evidence for the "cold dark matter" theory and shows how the mysterious stuff forms smaller clumps than scientists previously thought.
"We made a very compelling observational test for the cold dark matter model, and it passes with flying colors," Tommaso Treu, a professor in the Division of Astronomy and Astrophysics at the University of California, Los Angeles and a member of the team that made the Hubble observations, said in the NASA statement.
To indirectly observe and study dark matter, researchers use the effects of gravity in nearby stars and galaxies to detect dark matter and glean information about it. Previously, researchers have found evidence of clumps of dark matter near large and medium-size galaxies, but the clumps found in these new observations are the smallest ever detected.
Because scientists hadn't seen such small clumps of dark matter until now, some researchers had suggested that there might be "warm" dark matter particles that move around too quickly to form large structures, and thus form only smaller clumps. But with these observations, it's clear that "cold" dark matter particles can also form small clumps.
As scientists continue to (indirectly) observe and study dark matter, the mysterious material becomes less … well … mysterious. This work both reveals new information about dark matter and works to confirm presumptions made about the material that makes up such an enormous percentage of our universe.
"Dark matter is colder than we knew at smaller scales," Anna Nierenberg, a researcher at NASA's Jet Propulsion Laboratory who led the Hubble survey, said in the statement. "Astronomers have carried out other observational tests of dark matter theories before, but ours provides the strongest evidence yet for the presence of small clumps of cold dark matter. By combining the latest theoretical predictions, statistical tools and new Hubble observations, we now have a much more robust result than was previously possible."
The researchers behind these observations will present their results at the 235th meeting of the American Astronomical Society (opens in new tab) in Honolulu, Hawaii.
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The report shows HST images that support Einstein GR and gravitational lensing. I like to dig a bit deeper, here are two reports on WFI 2033-4723 (one of the HST views shown) showing its redshift number or z number and arcminute resolution in the spectra. H0LiCOW - X. Spectroscopic/imaging survey and galaxy-group identification around the strong gravitational lens system WFI 2033-4723
Here is another report, https://ui.adsabs.harvard.edu/abs/2019MNRAS.tmp.3214N/abstract
The upper range for the dark matter blob masses in the paper are 1 - 1,000 Msolar mass https://hubblesite.org/uploads/science_paper/file_attachment/526/stz3480.pdf ].
That fits nicely with the GD-1 streamer hole with its associated local sinusoidal wave centered on the hole. The discovery paper suggest - due to lack of visible candidates and a need for an extended mass - a passing by dark matter blob of ~ 10 Msolar mass https://www.skyandtelescope.com/astronomy-news/evidence-dark-matter-clump-milky-way/ ]: "According to the group’s simulations, the object would have been hefty — at least 5 million solar masses — but would have spanned between 60 and 130 light-years."
And that span is about the size of the Radcliff Wave similar hole that the ongoing AAS conference showed us the other day https://phys.org/news/2020-01-milky-reveals-giant-stellar-nurseries.html ]. There isn't any satellite galaxies on distances that could have passed by at the time I think , so a dark matter blob could be behind the sinusiodal GD-1 like wave.
Good information and links provided, thanks.
In 1931, Einstein made a trip to Mount Wilson to thank Hubble for providing the observational basis for modern cosmology.
The cosmological constant has regained attention in recent decades as a hypothesis for dark energy.
Einstein had a different theory until Hubble "Proved" him wrong through his observations. Again, we are in a cloud of dust that Hubble did not know about when he made his measurements. The equipment he used to do this is less accurate than what people have at home and this effectively ended the search for an answer. If Hubble was wrong, then it doesn't allow for Einstein work, his own WORDS. The bending of light that has been observed is better explained through atmospheric lensing.
Hubble was able to plot a trend line from the 46 galaxies he studied and obtain a value for the Hubble constant of 500 km/s/Mpc (much higher than the currently accepted value due to errors in his distance calibrations). (See cosmic distance ladder for details.)
Hubble's law - Wikipedia
This is so wrong it is terrible. It acts as if space is homogenous and it is in the article very clearly.
Idealized Hubble's lawedit] The mathematical derivation of an idealized Hubble's law for a uniformly expanding universe is a fairly elementary theorem of geometry in 3-dimensional Cartesian/Newtonian coordinate space, which, considered as a metric space, is entirely homogeneous and isotropic (properties do not vary with location or direction). Simply stated the theorem is this:
In fact this applies to non-Cartesian spaces as long as they are locally homogeneous and isotropic; specifically to the negatively and positively curved spaces frequently considered as cosmological models (see shape of the universe).
An observation stemming from this theorem is that seeing objects recede from us on Earth is not an indication that Earth is near to a center from which the expansion is occurring, but rather that every observer in an expanding universe will see objects receding from them.