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Case for axion origin of dark matter gains traction:
The existence of dark matter has been confirmed by several independent observations, but its true identity remains a mystery. According to this study, axion velocity provides a key insight into the dark matter puzzle. Previous research efforts have successfully accounted for the abundance of dark matter in the universe; however certain factors, such as the underproduction of axions with stronger ordinary matter interactions, remained unexplored.
By assigning a nonzero initial velocity to the axion field, the team discovered a mechanism—termed kinetic misalignment—producing far more axions in the early universe than conventional mechanisms. The motion, generated by breaking of the axion shift symmetry, significantly modifies the conventional computation of the axion dark matter abundance. Additionally, these dynamics allow axion dark matter to react more strongly with ordinary matter, exceeding the prediction of the conventional misalignment mechanism.
"The extensive literature on the axion was built upon the assumption that the axion field is initially static in the early universe," stated Keisuke Harigaya of the Institute for Advanced Study. "Instead, we discovered that the axion field may be initially dynamic as a consequence of theories of quantum gravity with axions."
Journal Reference:
Raymond T. Co, Lawrence J. Hall, Keisuke Harigaya. Axion Kinetic Misalignment Mechanism [open], Physical Review Letters (DOI: 10.1103/PhysRevLett.124.251802)
(Score: 2) by hendrikboom on Saturday June 27 2020, @12:37PM (3 children)
I do not understand what this summary could be saying.
What do the terms "initial velocity" and its apparent opposite, "static", even mean in a relativistic universe?
-- hendrik
(Score: 2) by Rupert Pupnick on Saturday June 27 2020, @01:05PM
And what does it mean for a “field” to have “velocity”? Certainly (as in EM theory) you can have waves within a field with velocity, but the field itself?
(Score: 3, Informative) by maxwell demon on Saturday June 27 2020, @01:10PM (1 child)
From a (very) quick look into the actual article, it seems that “velocity” here refers to the rate of change of field strength. “Static” then means the field does not change with time.
Relativity may affect how fast you perceive a field changing, but not whether it changes at all (well, there is an intermixing between spatial and temporal change, but I guess the static scenario also involved a spatially constant field)
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by hendrikboom on Sunday June 28 2020, @01:54AM
That make sense. Thank you.