Posts Tagged ‘MOND kaput’

Galaxy Without Dark Matter Found: Another Proof of New Physics?

March 31, 2018

ASTRONOMERS OGLE GALAXY DEVOID OF DARK MATTER!

The newfound object NGC 1052-DF2, a vast, diffuse galaxy, defies conventional explanations. It is to be feared (just kidding!) that various breakthroughs are in the offing, including in fundamental physics (if I believe that what could be true, SQPR, a proposed new foundation for physics, is really true).

The “ultra-diffuse” galaxy NGC1052-DF2, seen here in an image from the Hubble Space Telescope, is the same size as our Milky Way but contains just 1 percent as many stars. It also appears to be empty of Dark Matter. And therein a big problem for Conventional Wisdom:

Yes, that’s a galaxy… Looks dark, but without DM… Nothing the LCDM model saw coming… Is resistance to the New Physics Futile?
NGC1052-DF2 doesn’t look like a typical spiral or elliptical galaxy, but rather a loosely connected glob of star-pocked gas and dust. If it contained an amount of Dark Matter typical for a galaxy of its size, the Dark Matter’s gravity would hasten the motions of several star clusters that orbit it. Instead, van Dokkum’s team found those star clusters moving languidly around NGC 1052-DF2… That suggests Dark Matter can decouple not only from regular, visible matter, but from entire galaxies—a phenomenon LCDM cosmologists claimed couldn’t happen.

Large galaxies, radiant agglomeration of stars, are tied up together by the gravitational pull of Dark Matter, a hidden material that is revealed and observed by its gravitational pull upon the shiny stars it seems to outmass by a factor of ten (we know this from the virial theorem, which basically say: v^2 ~ M/R, where M is the global gravitational mass, v the (“dispersion”) speed, and R the radius where the speed is measured; so the higher the speed of the orbiting stars, clusters, galaxies, at the greater distance, the higher the global mass M).

Dark Matter is considered to be as a defining feature of galaxies as stars and gas… and is thought in the reigning LCDM model, to provide the gravitational seeds from which galaxies assemble and grow (a top cosmologist Sean Carroll insisted on this point in correspondence with me). I strongly disagree with the latter point (in my model, Dark Matter is EMERGENT, a fruit of the Quantum Interaction).

A galaxy without Dark Matter—or without some bizarre, twisted deformation of gravity (such as MOND) that would mimic Dark Matter behavior, in some, only some, cases, and not in cases such as the Bullet Cluster —would contradict the religion of LCDM (Lambda Cold Dark Matter) and the sect of MOND, in other words, such a heretical galaxy would shred official thinking and its main alternative. Yet that is exactly what Yale University astronomer Pieter van Dokkum and his colleagues have found, they report in a study published Wednesday in Nature.

From the horse’s mouth:

A GALAXY LACKING DARK MATTER

(Pieter van Dokkum and Al.)

Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio Mhalo/Mstars has a minimum of about 30 for galaxies with stellar masses near that of the Milky Way (approximately 5 × 10^10 solar masses) and increases both towards lower masses and towards higher masses… Here we report the radial velocities of ten luminous globular-cluster-like objects in the ultra-diffuse galaxy NGC1052–DF2, which has a stellar mass of approximately 2 × 10^8 solar masses. We infer that its velocity dispersion is less than 10.5 kilometres per second with 90 per cent confidence, and we determine from this that its total mass within a radius of 7.6 kiloparsecs is less than 3.4 × 10^8 solar masses. This implies that the ratio Mhalo/Mstars is of order unity (and consistent with zero), a factor of at least 400 lower than expected. NGC1052–DF2 demonstrates that dark matter is not always coupled with baryonic matter on galactic scales.

The twelve (!) authors from Yale, Harvard, Heidelberg, Santa Cruz, who used the giant Keck observatory in Hawai’i, don’t shrink from the exciting consequences:

Regardless of the formation history of NGC1052–DF2, its existence has implications for the dark matter paradigm. Our results demonstrate that dark matter is separable from galaxies, which is (under certain circumstances) expected if it is bound to baryons through nothing but gravity. The ‘bullet cluster’ demonstrates that dark matter does not always trace the bulk of the baryonic mass, which in clusters is in the form of gas. NGC1052–DF2 enables us to make the complementary point that dark matter does not always coincide with galaxies either: it is a distinct ‘substance’ that may or may not be present in a galaxy. Furthermore, and paradoxically, the existence of NGC1052–DF2 may falsify alternatives to dark matter. In theories such as modified Newtonian dynamics (MOND) and the recently proposed  emergent gravity paradigm, a ‘dark matter’ signature should always be detected, as it is an unavoidable consequence of the presence of ordinary  matter. In fact, it had been argued previously that the apparent absence of  galaxies such as NGC1052–DF2 constituted a falsification of the standard cosmological model and offered evidence for modified  gravity. For a MOND acceleration scale of a0 = 3.7 × 103 km2 s−2 kpc−1, the expected28 velocity dispersion of NGC1052–DF2 is σM ≈  (0.05GMstarsa0)1/4 ≈ 20 km s−1, where G is the gravitational constant—a factor of two higher than the 90% upper limit on the observed dispersion.

So exit MOND, Modified Newtonian Dynamics, once again! How many times do we need to kill that vampire? MOND is philosophically ugly, as it is an ad hoc theory; strictly engineered to explain a peculiar feature that is observed… Whereas my own theory, SQPR, was invented for reasons which have strictly to do with the foundations of Quantum Theory, and Dark Matter, and, moreover, Dark Matter as it turns out to be, is just a particular consequence.

***

SQPR, Sub Quantum Patrice Reality Shines, Once Again:

In SQPR, Dark Matter is created by the Quantum Interaction, at particular cosmic distances from ordinary matter, and only then. The density of matter at cosmic distances needs to be just so, otherwise Dark Matter, Patrice’s way, will NOT decouple from normal matter. Instead the galaxy will not develop Dark Matter, just DELOCALIZED Matter.

So how did we get to the present situation, as found in NGC1052–DF2? Suppose the existence of an ultra diffuse gas, on a larger scale than the Milky Way, way back in time. Under its own gravity, the ultra diffuse gas, will gather, and form stars. What is the difference with LCDM? In LCDM, Dark Matter is present to start with, seeds and accelerates galaxy formation.

Whereas in my model, the universe, being much older, perhaps 100 billion years old, there is no need for Dark Matter to seed galaxies: in complete contrast with LCDM, there is plenty of time for ultra diffuse gas to gather into ultra diffuse galaxies…. So this is not just about Dark Matter: the way I see it, it’s the entire vision of cosmology and the Quantum, which is in question.

Patrice Aymé

***

Contextual Notes: 1) Only discovered in 2015, ultra-diffuse galaxies are thought cosmic laboratories for Dark Matter. Surely, astronomers thought, Dark Matter must provide severely needed mass to form these objects so devoid of normal stars. That thinking led van Dokkum and his colleagues to build the Dragonfly Telephoto Array, a telescope in New Mexico created for the express purpose of scrutinizing ultra-diffuse galaxies. The researchers initially used Dragonfly to study a different galaxy, which possesses an almost inconceivably gargantuan amount of dark matter, a “weird” result in and of itself. When van Dokkum and his team found NGC 1052-DF2, they expected to see something similar.

“Instead we saw the opposite, leading to this remarkable conclusion that there’s actually no room for dark matter at all in this thing,” van Dokkum says. “It’s not something we were looking for or expecting. At all. But you go in the directions the data takes you, even if it’s in contradiction to what you’ve found before.”

In Dragonfly images, NGC 1052-DF2 looked like a standard ultra-diffuse galaxy. But when the team compared them to a better image from the Sloan Digital Sky Survey, they found a surprising mismatch. What had seemed to be dim basic galactic structures in Dragonfly’s view appeared as point-like sources in the Sloan image. To resolve the discrepancy, the team scrutinized the galaxy with the Hubble Space Telescope, the W.M. Keck Observatory and the Gemini Observatory, the latter two on giant volcano Mauna Kea in Hawaii.

The point sources proved to be 10 globular clusters—compact and spherical groupings of stars orbiting the galaxy’s core. The researchers then set about measuring the movements of the clusters as a way to estimate the galaxy’s total mass. Simply put, the velocity at which clusters orbit a galaxy is related to the amount of matter—normal or dark—that a galaxy contains. Using information from the Keck telescopes, the team found the globular clusters were moving much more slowly than expected. And therefrom the tale above…

2) Without modifying vastly the age of the universe, as I boldly suggest, there are a few theories to explain how galaxies like NGC 1052-DF2 could come together without being seeded by Dark Matter (as LCDM necessarily has it). That would be a downer (for me!) but, in the interest of scientific fairness, let’s mention them.

It could be that NGC 1052-DF2 was once a glob of gas perturbed by another unseen (?) galaxy nearby, sparking DF2 star formation. Or, van Dokkum speculates, perhaps this ultra-diffuse, dark-matter-free galaxy arose from two streams of gas that collided and compressed to form a scattering of stars. Another idea, first proposed more than two decades ago by Yale astronomer Priyamvada Natarajan, suggests galaxies like NGC 1052-DF2 form from galaxy-sized globs of gas clumping together in jets ejected by supermassive black holes in large galaxies’ hearts. NGC1052-DF2 does reside in a region where such things could occur, as it lies near a giant elliptical galaxy, those are the largest galaxies, with a supermassive black hole at its heart.

Notice that, in any case, it looks bad for MOND… MOND has several variants, but, basically, says that, at the scale of 50,000 light years (say) gravity, as described by the French astronomer Ismael Bullaldius (Ismaël Boulliau), a notion picked up by Hookes, Newton, etc. and amply confirmed since on the scale of the Solar System, is actually false. Thus the virial theorem (see above), at the scale of R = 50,000 light years, should be false. But above, everybody (not just me, but also the honorable professional astronomers) assumed it was true! Not just that, but the pull of gravity was observed to be just as needed. MOND assumes it’s stronger! So MOND, in case there is indeed NO apparent Dark Matter in NGC 1052-DF2, predicts the existence of NEGATIVE mass (reference the movies Avatar? I presume?) Laughter, please!

In any case, time will tell… Paradigm shift, or overlooked subtleties? Big telescopes are coming soon to a desert near you…