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This weird galaxy is missing all of its dark matter and scientists can't explain it


Oct 22, 2019
I note from the article, "This is, of course, what we thought and hoped for because it confirms our previous measurements," Mancera Piña said in a statement. "But now the problem remains that the theory predicts that there must be dark matter in AGC 114905, but our observations say there isn't. In fact, the difference between theory and observation is only getting bigger."

It is refreshing to see objective and *honest* statements about DM searches and observations. Another report on this DM problem is: https://phys.org/news/2021-12-evidence-emerges-dark-matter-free-galaxies.html

"An international team of astronomers led by researchers from the Netherlands has found no trace of dark matter in the galaxy AGC 114905, despite taking detailed measurements over a course of fourty hours with state-of-the-art telescopes."

Reference paper, No need for dark matter: resolved kinematics of the ultra-diffuse galaxy AGC 114905, https://arxiv.org/abs/2112.00017, 30-Nov-2021.

I note this in the phys.org report. "The prevailing idea is that all galaxies, and certainly ultra-diffuse dwarf galaxies, can only exist if they are held together by dark matter."

DM is needed if galaxies are moving and spinning for billions of years but dynamic time in galaxies may not reflect this, no need for DM. On page 2 of the 14 page arXiv paper, "2 DATA AND PROPERTIES OF AGC 114905 AGC 114905 (01:25:18.60, +07:21:41.11, J2000) lies at a (Hubble-flow) distance 𝐷 = 76 ± 5 Mpc (Leisman et al. 2017). The stellar distribution of AGC 114905, consists of an exponential disc with a disc scale length 𝑅d = 1.79±0.04 kpc." My note. 76 Mpc = 2.4787885E+08 LY or 248 million light years distance. My observation. One arcsecond angular resolution at 76 Mpc = 7.6000E+07 AU or 76 million AU diameter, 1.2018E+03 LY, 1201.8 light years. On page 4 of the arXiv paper, "3.2 Kinematic modelling With the position angle and inclination determined, we proceeded to perform our kinematic modelling with 3DBarolo, leaving as free parameters the systemic velocity (𝑉sys), the rotation velocity (𝑉rot), and the velocity dispersion (𝜎HI ). We fit an azimuthal model and we use a ring separation of 6 arcsec. This represents a minor oversampling of less than 10 percent with respect to the size of the beam along the major axis of the galaxy (6.5 arcsec), allowing us to trace the rotation curve of the galaxy with five, basically uncorrelated, resolution elements per galaxy side. We also check that the rotation velocities obtained using four or five rings (see below) are well consistent with each other." My note. 6.5 arcsec at 76 Mpc = 7.8114E+03 LY, 7811.4 light years diameter.