Research team finds a universal law for galactic systems

Posted: February 17, 2017 by oldbrew in Astronomy, Astrophysics, research
Tags: ,

gr_prob
The research team thinks its results are ‘difficult to understand in terms of dark matter’, reports Phys.org. The study was earlier reported here.

The distribution of normal matter precisely determines gravitational acceleration in all common types of galaxies, a team led by Case Western Reserve University researchers reports.

The team has shown this radial acceleration relation exists in nearby high-mass elliptical and low-mass spheroidal galaxies, building on last year’s discovery of this relation in spiral and irregular galaxies.

This provides further support that the relation is tantamount to a new natural law, the researchers say.

“This demonstrates that we truly have a universal law for galactic systems,” said Federico Lelli, formerly an astronomy postdoctoral fellow at Case Western Reserve University and currently a fellow at the European Southern Observatory.

“This is similar to the Kepler law for planetary systems, which does not care about the specific properties of the planet. Whether the planet is rocky like Earth or gaseous like Jupiter, the law applies,” said Lelli, who led this investigation.

In this case, the observed acceleration tightly correlates with the gravitational acceleration from the visible mass, no matter the type of galaxy. In other words, if astronomers measure the distribution of normal matter, they know the rotation curve, and vice versa. “But it is still unclear what this relation means and what is its fundamental origin,” Lelli said.

The study is published online in Astrophysical Journal today. Co-authors are Stacy McGaugh, chair of the Department of Astronomy at Case Western Reserve, James Schombert, astronomy professor at the University of Oregon, and Marcel Pawlowski, former astronomy postdoctoral researcher at Case Western Reserve and current Hubble fellow at the University of California, Irvine.

The researchers found that in 153 spiral and irregular galaxies, 25 ellipticals and lenticulars, and 62 dwarf spheroidals, the observed acceleration tightly correlates with the gravitational acceleration expected from visible mass.

Observed deviations from this correlation are not related to any specific galaxy property but completely random and consistent with measurement errors, the team found.

The tightness of this relation is difficult to understand in terms of dark matter as it’s currently understood, the researchers said.

It also challenges the current understanding of galaxy formation and evolution, in which many random processes such as galaxy mergers and interactions, inflows and outflows of gas, star formation and supernovas, occur at the same time.

“Regularity must somehow emerge from this chaos,” Lelli said.

The report continues here.

Comments
  1. oldbrew says:

    Dark matter seems to be a theory in search of some facts.

  2. Paul Vaughan says:

    “[…] as it’s currently understood […] It also challenges the current understanding […]”

    It’s just like climate.

    “[…] as it’s currently misunderstood […] It also underscores current misrepresentation […]” [typos corrected]

  3. oldbrew says:

    “But it is still unclear what this relation means and what is its fundamental origin,” Lelli said.
    – – –
    More work for science to do. At least an observation (‘universal law’) has been made as a starting point.

  4. rishrac says:

    Do they rotate in the same direction ? If it’s universal then the dark matter would always cause a galaxy to spin in the same direction. And then there is the expansion problem. What fills the void as the universe expands? And as individual stars revolve around a core galactic center, some are moving faster than others. How is the expansion uniform in the presence of varying gravitational differences ? We know that there are ripples in the fabric of space when black holes merge, what’s to prevent it from tearing apart ?

  5. Jason Calley says:

    Dark matter has always seemed way too ad hoc to be good science.

    Do any of the regulars here have an opinion on this guy: http://physicsfromtheedge.blogspot.co.uk/
    He has a theory based on what I understand to be a sort of large scale version of the Casimir effect. It seems to explain all the dark matter stuff but does so from a much more fundamental, non-handwaving point of view. On the other hand, I may have simply missed some obvious problems. Any ideas or opinions?

  6. Sphene says:

    Just highly speculating here, if the observed galactic rotational curve really is the correct representation of gravity (with no dark matter), then should we be looking within planetary systems for a drag effect that is slowing orbits…?

  7. JB says:

    Tag: “baffled scientists” indeed. I hope that my grandkids when they arrive at my age now will have great belly-laughs over this, and other such absurdities, as “fabric” of space etc.

  8. JKrob says:

    oldbrew wrote –

    rishrac – re ‘Do they rotate in the same direction?’ – No.

    Well, isn’t kind of relative…depending on which ‘side’ of the galactic plane you are observing?

  9. oldbrew says:

    JK – not really, you would still see rotation in both directions.

  10. rishrac says:

    Old brew, I remember a discussion as to whether the universe had an up and down. If that unseen matter was uniform, then the galaxies would swirl in the same direction because there would have to be polarity. The push would always be from the same direction. … then it could be lumpy in places, like oatmeal . Caused by the expansion of the universe and the stretching of that space by the actually differential movement of strong gravitational centers. Something would have to decide which direction something would revolve or rotate sitting in that soup. Maybe something is bubbling through that so that one side of the object starts to move in that direction…

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