Acceleration as a function of radius in NGC 4455, one of the studied galaxies
Posted on 04/30/2019 8:34:49 PM PDT by ETL
Acceleration as a function of radius in NGC 4455, one of the studied galaxies
As fascinating as it is mysterious, dark matter is one of the greatest enigmas of astrophysics and cosmology
It is thought to account for 90 percent of the matter in the universe, but its existence has been demonstrated only indirectly, and has recently been called into question
New research conducted by SISSA removes the recent doubts on the presence of dark matter within galaxies, disproving the empirical relations in support of alternative theories.
The study, published in the Astrophysical Journal, also offers new insights into understanding the nature of dark matter and its relationship with ordinary matter.
From the expansion of the universe to the movement of stars in the galaxies, there are many phenomena that cannot be explained by the presence of baryonic matter alone.
The attractive force generated by matter is insufficient to explain observable gravitational effects. This had led to the theory of the existence of undetectable dark matter, and the idea that galaxies are embedded in its spherical halo.
"Three years ago, a few colleagues at Case Western Reserve University strongly questioned our understanding of the universe and the in-depth work of many researchers, casting doubt on the existence of dark matter in the galaxies," explains Chiara Di Paolo, a doctoral student of astrophysics at SISSA.
"Analyzing the rotation curves of 153 galaxies, principally the 'classical' spiral kind, they obtained an empirical relationship between total gravitational acceleration of the stars (observed) and the component which we would observe in the presence of only ordinary matter in the classical Newtonian theory.
This empirical relationship, which seemed valid in all the galaxies they analyzed and at any galactic radius, motivated the explanation of gravitational acceleration without necessarily calling into question dark matter, but involving, for example, theories of modified gravity such as modified Newtonian dynamics (MOND)."
Di Paolo and her collaborators wanted to verify this relationship, analyzing the rotation curves of galaxies other than the classical spiral kind—72 galaxies with low surface brightness (LSB) and 34 dwarf disc galaxies.
They produced more extended results, finding a relationship, which, besides total gravitational acceleration and its ordinary component, also involves the galactic radius and the morphology of the galaxies.
"We have studied the relationship between total acceleration and its ordinary component in 106 galaxies, obtaining different results from those that had been previously observed," explains Paolo Salucci, professor of astrophysics at SISSA and one of the research authors.
"This not only demonstrates the inexactness of the empirical relationship previously described but removes doubts on the existence of dark matter in the galaxies.
Furthermore, the new relationship found could provide crucial information on the understanding of the nature of this indefinite component."
Below is a link to an interesting related article on galaxy structure...
Why Aren’t Spiral Galaxies More Wound Up?
It’s rare to find a galaxy where the arms wrap around even a full 360 degrees. But after billions of years, why is that?
Amazing stuff! So amazing and complex that it is obvious an amazing, all-powerful God created this marvelous universe!
They believe dark matter exists BUT they have no idea what it is.
I kinda like the old term because it makes me think of fudge. :)
Another picture:
https://www.cnn.com/videos/world/2019/04/30/space-black-hole-plasma-clouds-wobble-icrar-lon-orig.cnn
I thought nothing can escape from black holes, but this shows plasma spewing out.
Oops, by the time I posted the link they changed it. now it shows a hedgehog.
I did not confuse a black hole with a hedgehog.
Thanks for posting.
Very interesting, but difficult to completely understand.
.
They’re trying to figure out the galaxy rotation curve problem.
The claim that this removes doubts about dark matter though is cultish in its ludicrousness.
> They believe dark matter exists BUT they have no idea what it is.
Dark matter is literally “presumed stuff where it would need to be to keep current theories intact”.
Used to be that the need to do something like this to keep the theory intact was considered enough to falsify the theory.
But if the theory is unfalsifiable by doctrine, you get nonsense like dark matter to make it work.
First time I have heard about it.
I know God exists or a Creator simply by seeing an attractive lady while grocery shopping. Duh!
I don’t need any fancy smancy advanced math for that one.
Sure, she just randomly evolved from nothing. Yah rrrriiiiggghhhttt. ;-)
Everything makes sense.
later
Thanks ETL.
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