Dark matter clue? Mysterious substance may be interacting with itself in nearby galaxy

[Admin]

A neighbor galaxy of the Milky Way could offer fresh clues in the 90-year-long quest to determine the nature of dark matter.

Dark matter clue? Mysterious substance may be interacting with itself in nearby galaxy : Read more

 

[Unclear Engineer]

I am left wondering why the Crater II galaxy is "unusual" if its features are caused by "Self Interacting Dark Matter" and "dark matter" is supposedly everywhere and 6 times the amount of regular matter.

Is the hypothesis that there are different kind of "dark matter" that cluster in different galaxies?

That seems like a weird concept for a cosmology based on the principle that the universe is the same everywhere, at least on a large scale.

Frankly, it seems like "cherry picking" the observations to support an hypothesis, rather than the discovery of some universal physics.

 

[Zdepthcharge]

Frankly, it seems like "cherry picking" the observations to support an hypothesis, rather than the discovery of some universal physics.

Throughout the 90s particulate dark matter seemed to be picking up a new superpower every time you turned around. Consistency is not a component of any particulate dark matter theory.

 

[Questioner]

"...its dark matter halo — a spherical, invisible structure surrounding Crater II ..."

That geometry fits with a single, if tremendously huge mass source.
As if that galaxy’s center had a 'flat' mass curve source extending far outward from its central black hole.

 

[Torbjorn Larsson]

The Crater II was flagged as extreme, cold and dark with dark matter dominating normal matter with a factor 100:1 in the center and more at the edges. Despite that I don't see that the new paper tried to fit a cold dark matter model with the original paper suggestions of how an expanded dark matter halo can result:

For example, star formation and subsequent supernova winds can give up gravitational energy to standard “cold” dark matter (CDM), lowering halo concentration as dark matter expands nonadiabatically (Pontzen & Governato 2014, and references therein).

So this single example of SIDS fit is dubious. Notably only one interaction strength gave a good fit, indicating lack of robustness, perhaps that model too would have benefitted from the above suggestions.

More generally, cold dark matter is evidenced in many different ways, so the new topic of extremely dilute dwarf galaxies is on the edge of an else well researched theory. And even if a particular SIDS would fit better, it would have to be tested on all those other cases.

Throughout the 90s particulate dark matter seemed to be picking up a new superpower every time you turned around. Consistency is not a component of any particulate dark matter theory.

Claims made without evidence can be dismissed without evidence.

But as it happens, Cold Dark Matter models have been consistent for half a century:

The theory of cold dark matter was originally published in 1982 by James Peebles;[ ... In the cold dark matter theory, structure grows hierarchically, with small objects collapsing under their self-gravity first and merging in a continuous hierarchy to form larger and more massive objects. Predictions of the cold dark matter paradigm are in general agreement with observations of cosmological large-scale structure. ... Since the late 1980s or 1990s, most cosmologists favor the cold dark matter theory (specifically the modern Lambda-CDM model) as a description of how the universe went from a smooth initial state at early times (as shown by the cosmic microwave background radiation) to the lumpy distribution of galaxies and their clusters we see today—the large-scale structure of the universe. Dwarf galaxies are crucial to this theory, having been created by small-scale density fluctuations in the early universe;[5] they have now become natural building blocks that form larger structures.

https://en.wikipedia.org/wiki/Cold_dark_matter