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Abstract: We tentatively look at anthropic constraints on the Cosmological ConstantCC \Lambda at galactic scales by investigating its influence on the motion ofthe Sun throughout the Milky Way MW for -4.5 <= t <=0 Gyr. In particular, welook at the Galactocentric distance at which the Sun is displaced at the end ofthe numerical integration of its equations of motion modified in order toinclude the effect of \Lambda as well. Values of it placing our star at itsbirth at more than 10 kpc from the Galactic center GC are to be consideredimplausible, according to the current views on the Galactic Habitable ZoneGHZ on the metallicity level needed for stars- formation. Also valuesyielding too close approaches to GC should be excluded because of the risks tolife-s evolution coming from too much nearby supernovae SN explosions andGamma Ray Bursts GRB. We investigate the impact on our results of theuncertainties on both the MW model-s parameters and the Sun-s initialconditions, in particular the Hubble parameter H 0 and the Local Standard RestLSR speed \Theta 0 accurate at 2% and 6.2% level, respectively. WhileH 0=70.1 km s^-1 Mpc^-1, \Theta 0=254 km s^-1 and \Lambda <= 10^-55 cm^-2locates the place of birth of the Sun at 19.6 kpc from GC, the same values forH 0 and \Lambda, and \Theta 0^max=270 km s^-1, places it at the plausibleGalactocentric distance of 8.5 kpc. \Lambda = 10^-54 cm^-2 and \Lambda = 10^-53cm^-2 place the Sun at 10.6 kpc and 18.7 kpc, respectively.



Author: Lorenzo Iorio

Source: https://arxiv.org/



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