An international group of astronomers, led by a physicist at the University of St Andrews, has revived an alternative theory of gravity.
Led by Dr. Indranil Banik of the University of St Andrews School of Physics and Astronomy, said the study revealed estimates of the high rotational velocities of gas in the dwarf galaxy, consistent with an already debunked theory known as Milgromian Dynamics (MOND).
An earlier study of the speed of gas rotation in the dwarf galaxy AGC 114905 (Mancera Pena et al., 2022) found that the gas turned very slowly and thus claimed that the WORLD theory was dead.
These theories are important for understanding our universe because, according to known physics, galaxies are rotating so fast that they must diverge with each other. WORLD is a controversial alternative to general relativity, Einstein’s dominant understanding of the phenomenon of gravity. However, general relativity requires dark matter to hold galaxies together, whereas WORLD does not.
Since dark matter has never been found despite decades of very sensitive research, several theories have been proposed to explain what holds galaxies together. Enraged debate over the correct theory. Very low turning speeds are reported in the Mancera Pina et al study to meet expectations in a world governed by general relativity and large amounts of black matter.
Dr. Group Banks argues that the high rotational speed predicted in the WORLD’s theory of gravity is consistent with observations of whether the galaxy’s tilt is excessive.
The rotation of stars and gases in distant galaxies cannot be measured directly. Only on-line components of vision are known by accurate spectroscopic measurements. If galaxies were seen almost directly, most of them would orbit the celestial plane. This may mislead observers into thinking that galaxies are rotating very slowly, requiring them to exaggerate the slope between the cylinder and the celestial plane. This inclination is estimated from the way elliptical galaxies appear (see image).
The new study explores this important issue using detailed WORLD simulations of a similar disk galaxy AGC 114905 Created at the University of Bonn by Srikanth Nagesh and at the instigation of Pavel Kroupa, Professor at the University of Bonn and Charles University in Prague. The simulations show that it can appear a bit elliptical even when viewed directly. This is because the stars and gases in galaxies have gravity and can pull themselves into a somewhat non-circular shape. A similar process causes spiral arms to appear in disk galaxies, a feature so common that they are often called spiral galaxies.
As a result, the galaxy may be closer to confrontation than observers think. This could mean that the galaxy is spinning faster than reported, removing the strain from the MOD.
Dr. Banek, the lead author of the new study, said: “Our simulations suggest that the tilt of AGC 114905 may be much lower than previously reported, meaning that the galaxy is actually rotating faster than humans think, in line with predictions. WORLD. ”
Hongsheng Zhao, from the School of Physics and Astronomy at St Andrews University, said: this is apparent. ” .
The new study also argues that a similar “pseudo-tilt” effect is unlikely to reach the standard black matter approach because the galaxy is dominated by a halo of fine black matter. The star and gas contribute slightly to gravity, so the disk is not “self-gravity”.
This means that it is likely to appear very circular when viewed live, as confirmed by other group simulations (Selwood and Sanders, 2022). As a result, the observed ellipsoid must be caused by a significant tilt between the disc and the celestial level. The speed of the rotation will be very slow, meaning that the galaxy contains very little dark matter. In this context, an isolated dwarf galaxy is unlikely to contain a small amount of dark matter if given its mass of stars and gas.
Pavel Krupa, a professor at the University of Bonn and Charles University in Prague, said in the broader context of the following conclusions: ” in dwarf galaxies like AGC 114905 down to the cosmic scale, as many independent teams find. “
References: “Overtendency of the Milgromian Disc Galaxy: The Case of the Ultra-Wending Galaxy AGC 114905” by Indranil Banik, Srikanth T Nagesh, Hosein Haghi, Pavel Kroupa, Hongsheng Zhao, April 19, 2022, Monthly notice from the Royal Astronomical Society.
DOI: 10.1093 / mnras / stac1073
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