Can the ΛCDM model reproduce MOND-like behavior?

摘要

It is usually believed that MOND can describe the galactic rotational curves with only baryonic matterand without any dark matter very well, while the ΛCDM model is expected to have difficulty inreproducing MOND-like behavior. Here, we use EAGLE’s data to learn whether the ΛCDM model canreproduce MOND-like behavior. EAGLE’s simulation result clearly reproduces the MOND-like behaviorfor a_b⪆10~(−12) m/s~2 at z = 0, although the acceleration constant, a0, is a little larger than the observationaldata indicate. We find that a_0 increases with the redshift in a way different from what Milgrom proposed(a_0 ∝ H). Therefore, while galaxy rotation curves can be fitted by MOND’s empirical function in theΛCDM model, there is no clear connection between a_0 and the Hubble constant. We also find that a0 atz⪆1 is well separated from a0 at z = 0. Once we have enough galaxies observed at high redshifts, wewill be able to rule out the modified gravity model based on MOND-like empirical function witha z-independent a_0.