The core conclusion is actually decades old. But, the bottom line is that MOND is much closer to right when it comes to the time frame in which galaxies start to appear than the LambdaCDM Standard Model of Cosmology.
Studies of stellar populations in early-type galaxies (ETGs) show that the more massive galaxies form earlier and have a shorter star formation history (SFH). In this study, we investigate the initial conditions of ETG formation. The study begins with the collapse of non-rotating post-Big-Bang gas clouds in Milgromian (MOND) gravitation. These produce ETGs with star-forming timescales (SFT) comparable to those observed in the real Universe. Comparing these collapse models with observations, we set constraints on the initial size and density of the post-Big-Bang gas clouds in order to form ETGs. The effective-radius-mass relation of the model galaxies falls short of the observed relation. Possible mechanisms for later radius expansion are discussed. Using hydrodynamic MOND simulations this work thus for the first time shows that the SFTs observed for ETGs may be a natural occurrence in the MOND paradigm. We show that different feedback algorithms change the evolution of the galaxies only to a very minor degree in MOND. The first stars have, however, formed more rapidly in the real Universe than possible just from the here studied gravitational collapse mechanism.
Dark-matter-based cosmological structure formation simulations disagree with the observed SFTs at more than 5 sigma confidence.
Robin Eappen, Pavel Kroupa, Nils Wittenburg, Moritz Haslbauer, Benoit Famaey, "The formation of early-type galaxies through monolithic collapse of gas clouds in Milgromian gravity" arXiv:2209.00024 (August 31, 2022).
The first stars have, however, formed more rapidly in the real Universe than possible just from the here studied gravitational collapse mechanism. Dark-matter-based cosmological structure formation simulations disagree with the observed SFTs at more than 5 sigma confidence.
ReplyDeletesimulations :/