As explained in a Triton Station blog post, the MOND-like behavior of galaxies called the "radial acceleration relation" holds true for galaxies of all sizes and shapes.
The post notes that "an apparent offset between early type galaxies (ETGs, aka ellipticals) and late type galaxies (LTGs, aka spirals)" turns out to be a statistical artifact of analyzing the samples in an inconsistent manner.
Figure 3 from Mistele et al. (2024). The baryonic Tully–Fisher relation implied by weak lensing for the entire sample (yellow symbols, left column) and for ETGs and LTGs separately (red and blue symbols, right column). The Vflat values are weighted averages of the Vc values shown in Figure 1 for 50 kpc < R < 300 kpc (first row) and 50 kpc < R < 1000 kpc (second row). Vertical error bars represent a 0.1 dex systematic uncertainty on M*/L. For comparison, we also show the best fit to the kinematic data from Lelli et al. (2019; solid gray line) and the corresponding binned kinematic data (white diamonds).
We combine kinematic and gravitational lensing data to construct the Radial Acceleration Relation (RAR) of galaxies over a large dynamic range.
We improve on previous weak-lensing studies in two ways. First, we compute stellar masses using the same stellar population model as for the kinematic data. Second, we introduce a new method for converting excess surface density profiles to radial accelerations. This method is based on a new deprojection formula which is exact, computationally efficient, and gives smaller systematic uncertainties than previous methods.
We find that the RAR inferred from weak-lensing data smoothly continues that inferred from kinematic data by about 2.5 dex in acceleration. Contrary to previous studies, we find that early- and late-type galaxies lie on the same joint RAR when a sufficiently strict isolation criterion is adopted and their stellar and gas masses are estimated consistently with the kinematic RAR.
T. Mistele, S. McGaugh, F. Lelli, J. Schombert and P. Li, "Radial acceleration relation of galaxies with joint kinematic and weak-lensing data" Journal of Cosmology and Astroparticle Physics (April 4, 2024) (open access). DOI 10.1088/1475-7516/2024/04/020.
Other papers also establish that these dynamics are present in galaxies are early as they can be detected with the James Webb Space Telescope (JWST), which has an ability to see faint, highly redshifted objects that is unparalleled. This is true even in galaxies that are visible before the LambdaCDM model says that they should exist at all.
7 comments:
I would like to see a resolution of the wide binaries test
what is your preferred explanation for galaxies clusters – dark matter or another modify gravity for galaxies clusters
Andrew apologies for nitpicking, but you have misspelled "Radial Acceleration Relation" and called it "Radical...," which might confuse some readers.
Certainly appreciate all the effort you put in on this site!
@siriusactuary
No need to apologize. I appreciate you catching that. I can't afford a paid copyeditor for my blog.
@neo
My preferred explanation for galaxy clusters is gravitational, specifically, the geometric approach proposed by Deur.
Deur argues that the phenomena attributed to dark matter are really GR/quantum gravity effects differing from Newtonian gravity arising from the self-interaction of gravitational fields, which arise only to the extent that the source matter distribution is not spherically symmetric. In an elliptical galaxy this secondary effect is modest. In a spiral galaxy this approaches a 1/r self-interaction force rather than a 1/r^2 in the ideal of a perfect thin disk. In a cluster, the galaxies are approximately point-like and the pull between them approaches that of a QCD flux tube that is approximately constant without regard to distance.
@neo
"I would like to see a resolution of the wide binaries test"
So would I. Sooner or later, we'll get a better answer. Probably in my lifetime. But these things take time. The data being used to evaluate wide binaries right now is on the very fringe where it might be possible to detect an effect but there is a partial external field effect, so its muddy. The question might not be resolved until we can look at wide binary data with no external field effect.
So would I. Sooner or later, we'll get a better answer. Probably in my lifetime. But these things take time.
speaking of which just today
https://doi.org/10.3390/universe10070285 - 29 Jun 2024
Post a Comment