A massive, rotating disk galaxy (opens in new tab)that first formed just 1.5 billion years after the Big Bang, could upend our understanding of galaxy formation, scientists suggest in a new study.
In traditional galaxy formation models and according to modern cosmology, galaxies are built beginning with dark-matter halos. Over time, those halos pull in gases and material, eventually building up full-fledged galaxies. Disk galaxies (opens in new tab), like our own Milky Way (opens in new tab), form with prominent disks of stars and gas and are thought to be created in a method known as "hot mode" galaxy formation, where gas falls inward toward the galaxy's central region where it then cools and condenses.
This process is thought to be fairly gradual, taking a long time. But the newly discovered galaxy DLA0817g, nicknamed the "Wolfe Disk," which scientists believe formed in the early universe, suggests that disk galaxies could actually form quite quickly.
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In a new study led by Marcel Neeleman of the Max Planck Institute for Astronomy in Germany, researchers spotted the Wolfe Disk using ALMA, the Atacama Large Millimeter/submillimeter Array in Chile. They found out that the object was a large, stable rotating disk, clocking in at a whopping 70 billion times the mass of our sun.
In the new observations, the disk appears as it was when the universe was just 1.5 billion years old, or 10% of its current age. The disk appears extremely massive and stable for something so young. So how could such a massive galaxy form so quickly, so early in the universe?
Researchers suggest that the galaxy might have formed by a process known as "cold-mode accretion." They think that the gas falling in towards the galaxy's center was actually cold so, because the gas didn't need time to cool down as it approached the galactic center, the disk was able to more rapidly condense.
"The result provides valuable input for a present-day discussion about how galaxies form," according to a statement (opens in new tab) from the Max Planck Institute.
However, astrophysicist Alfred Tiley noted in a Nature News & Views article accompanying this study, these findings are based off of a single galaxy. He emphasized that more similar observations would be needed to validate this hypothesis.
This work was published Wednesday (opens in new tab) (May 20) in the journal Nature.
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"Galaxy DLA0817g, nicknamed the Wolfe Disk after the late astronomer Arthur M. Wolfe, is the most distant rotating disk galaxy ever observed. The unparalleled power of ALMA made it possible to see this galaxy spinning at 170 miles (272 kilometers) per second, similar to our Milky Way."
I note that rotating at 272 km/s is similar to older reports for measuring the Sun's Local Standard of Rest (LSR) velocity in the Milky Way, A Large Local Rotational Speed for the Galaxy Found from Proper Motions: Implications for the Mass of the Milky Way
This is interesting. The massive rotating disk challenges BB cosmology model to explain how these galaxies formed so early in the BB model. I note the redshift or z = 4.2603 according to the link cited in the phys.org report: https://www.nature.com/articles/s41586-020-2276-y
"Abstract Massive disk galaxies like the Milky Way are expected to form at late times in traditional models of galaxy formation1,2, but recent numerical simulations suggest that such galaxies could form as early as a billion years after the Big Bang through the accretion of cold material and mergers3,4. Observationally, it has been difficult to identify disk galaxies in emission at high redshift5,6 in order to discern between competing models of galaxy formation. Here we report imaging, with a resolution of about 1.3 kiloparsecs, of the 158-micrometre emission line from singly ionized carbon, the far-infrared dust continuum and the near-ultraviolet continuum emission from a galaxy at a redshift of 4.2603, identified by detecting its absorption of quasar light. These observations show that the emission arises from gas inside a cold, dusty, rotating disk with a rotational velocity of about 272 kilometres per second. The detection of emission from carbon monoxide in the galaxy yields a molecular mass that is consistent with the estimate from the ionized carbon emission of about 72 billion solar masses. The existence of such a massive, rotationally supported, cold disk galaxy when the Universe was only 1.5 billion years old favours formation through either cold-mode accretion or mergers, although its large rotational velocity and large content of cold gas remain challenging to reproduce with most numerical simulations7,8."
Using the cosmology calculators for the BB model, z = 4.2603 is 12.276E+9 light-time distance from Earth. The comoving radial distance is much farther away, http://www.astro.ucla.edu/~wright/CosmoCalc.html
I don't know the distribution in galaxy rotation curves, but due to their similar formation histories - gas clouds streaming along galactic filaments - galaxy peculiar velocities (when expansion is accounted for) is much the same. It is a similar phenomena to stars withing Milky Way due to the rotation, relatively few stars are accelerated by gravitational sling shots.
The rotation of the disk is decided by the rotation of the about one order of magnitude more massive dark matter halo it is embedded in, but at the same radius - Wolfe disk ~ 10^11 stars, Milky Way ~ 10^(11-12) stars - I would then expect about the same rotational speed.
Apparently galaxy histories are constrained by the cosmic filament flow, so they start out with gas rotating with rotation axis parallel to the filament "narrow" axis and the rotation decided by the filament radius at a guess. Again, with rather narrow distribution of filament width follows narrow distribution of rotation. As the galaxies stream towards the filament nodes, and the filament narrows due to that mass redistribution and due to gravitational clumping within, they collide and rotation axis tips over to become perpendicular to the filament axis. IIRC Milky Way, which is relatively calm - it has seen mergers but has a moderate star formation rate and a moderately calm super massive black hole - is in between the two states (not tipped over vs tipped over). Assuming random collisions I would expect a slight broadening of the rotational distribution.
I think the problem here is to account for the cold gas pathway. But it has been done, I take it:
"Modern simulations of structure formation make use of supercomputers to follow dark matter and gas over billions of years after the big bang. In effect, they create a virtual universe, based on the known physical laws, that allows scientists to analyze all phases of cosmic evolution.
Two recent simulations, the smaller-scale Auriga simulation of Milky-Way-like galaxies and the large-scale detailed TNG50-Simulation, opened up the possibility of an alternative mode of formation: Already cold gas flowing into galaxies, following the filaments of the dark matter network, avoiding the collisions that would heat the gas up, allows for the formation of massive disk galaxies at much earlier times than the collision-and-cooling scenario."
There are still problems in the computer simulations to explain such large, rotation velocities reported for a galaxy with z=4.2603 spinning at some 270 km/s. We have reports showing dark matter has problems with the Milky Way, dwarf galaxy counts in the computer simulations. 'Groupie' galaxies orbiting Milky Way tell us about dark matter, how galaxy formed, "...Scientists have also extracted information about the halos of dark matter that surround these galaxies, as well as a prediction that our home galaxy should host an additional 100 or so very faint satellite galaxies awaiting discovery..."
My comment - *awaiting discovery*. We have another report out on DM too showing DM is entering a crisis phase now apparently. Milky Way Dark Matter Signals in Doubt after Controversial New Papers, 'Existential Crisis' "We know it’s there, but we don’t know what it is: this invisible stuff is dark matter. Scientists are fairly certain it dominates the cosmos, yet its ingredients are unclear." Now there is the scalar DM model under review, Searching for scalar dark matter using compact mechanical resonators
"Researchers hypothesize that ultralight dark matter is extremely light, lighter even than neutrinos. If such dark matter particles existed, their density would be so large that they would be better viewed as a fluid that permeates the galaxy, producing a wavelike disturbance on normal matter. "The ultralight dark matter hypothesis is motivated by string-theory scenarios, and moreover, might explain some puzzling discrepancies between the predictions of more prosaic dark molecules and the distribution of dark matter on galactic scales," Daniel Grin, another researcher involved in the study, told Phys.org... Overall, the recent study carried out by Singh, Manley, Grin, Wilson and their colleagues highlights the potential of state-of-the-art mechanical systems at the cm-scale for detecting dark matter in previously unexplored regimes, with individual particle masses ranging from 10^-48 kg to 10^-42 kg. In the future, these resonators could thus play a crucial role in the search for dark matter, particularly that in the ultra-light regime."
My observation. It should be pointed out that without DM, the BB model fails to create structure in the universe as it expands, thus no galaxies, no stars, no planets. Computer simulations using any form of DM, are model dependent upon this critical input parameter to make the simulations work. Presently, clearly identifying what DM is (assuming it exists), remains challenging in cosmology. When I use my telescopes to study the Galilean moons moving around Jupiter, DM is not visible or altering their orbits at Jupiter :)
I don't know the cosmic simulations enough to know if they have problems with statistics - they may see large disks, but maybe not so early and/or soo frequently as the observations now imply - but I note that the order of discovery was the simulations discovered the cold-mode accretion before the observation. The galaxy and star studies is after all the new research edge after inflation as well as dark energy and dark matter has become the best theory out there http://www.sciencemag.org/news/2018/05/galaxy-simulations-are-last-matching-reality-and-producing-surprising-insights-cosmic ].
The link you point to on satellite galaxies and the dark matter parameters we can extract from observation of Milky Way's satellites I would take as showing that we have less problems with Milky Way especially and dark matter in general. They confirm our understanding of both. And as a direct rejection of the somewhat "moon shot" continued search for scalar, axion like mass, dark matter you link to as somehow telling on dark matter in general. Those particles are natural in string theory but not seen since dark matter would be "fuzzy" and wave like, not cold and particle like https://scitechdaily.com/is-dark-matter-warm-cold-or-fuzzy-new-simulations-provide-intriguing-insights/ ].
A simulation of early galaxy formation under three dark matter scenarios. In a universe filled with cold dark matter, early galaxies would first form in bright halos (far left). If dark matter is instead warm, galaxies would form first in long, tail-like filaments (center). Fuzzy dark matter would produce similar filaments, though striated (far right), like the strings of a harp. Credit: Image courtesy of the researchers
The amount of dark matter spread out in the whole solar system averages an asteroid mass worth, much likely settled inside the Sun to boot. Why would you expect to see that gravitationally? https://www.forbes.com/sites/startswithabang/2018/03/24/ask-ethan-if-dark-matter-is-everywhere-why-havent-we-detected-it-in-our-solar-system/ ]
Torbjorn statement about the Sun, "The amount of dark matter spread out in the whole solar system averages an asteroid mass worth, much likely settled inside the Sun to boot."
In the BB model, there are indeed dark stars possible, Dark stars: a review "Abstract Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only ≲ 0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars."
DM in the Sun could perhaps, change stellar evolution theory and the EOS for p-p chain fusion in the Sun. We also have current efforts to observe and document DM on Earth, so far nothing identified showing DM, https://www.space.com/hunting-dark-matter-inside-earth.html There is the problem of the long age rotation of the solar system in the galaxy and capture or ejection of DM from the solar system over the long rotation history. Consider the Sun must complete about 18-20 galactic rotations based upon the radiometric age of meteorites used. There will be periods of DM capture or possible ejection that can alter the amount of DM claimed by some calculations used to show we should not see DM at Jupiter's Galilean moons today. Capture and Ejection of Dark Matter by the Solar System, Comments on recent work on dark-matter capture in the Solar System
So here is my view on the subject. So far, all efforts to identify what DM is have failed, both near and far. The computer simulations use of DM is a free parameter that can be adjusted as needed to get the output desired. I think computer simulations with free parameters should be clearly pointed out to the public in reports and the consequence of DM failing to be identified and what happens to the simulations if DM is not real. The BB model collapses. Thus, much is at stake here it seems to me---Rod
Here is an example of an objective and more accurate report on DM in the solar system, Measuring the local Dark Matter density in the laboratory I note this from the arxiv report. "Introduction. - A self-gravitating fluid that does not emit or absorb radiation at any observable wavelength, Dark Matter (DM) is the only coherent explanation for a number of otherwise anomalous phenomena ...While the evidence for the existence of DM in the Universe and in our own galaxy is compelling, there is no direct indication of the presence of DM within a sphere of radius about one parsec around the Sun . More specifically, there is no astronomical tracer that can currently be used to directly probe the DM contribution to the Milky Way gravitational potential with sub-parsec resolution . Consequently, any statement about the properties of the DM flux through our planet relies heavily on the extrapolation of DM density estimates performed on much larger scales... Each of these methods comes with its own limitations as well systematic and statistical errors ..."