Ciclo de Colóquios do PPGF

20/08/2019 @ 13:20 –

Ryo Namba (McGill University, Montreal,
Canada)
Title: Energy Injection into CMB from Axion-Gauge Field Dynamics

Data / Hora
20/08/2019
13:20

Localização
Sala de seminários João Salim Miguel – 3144 – bloco F – 3º andar.
Rio de Janeiro, RJ


Measurements of the cosmic microwave background (CMB) radiation in the last
half century have immensely advanced our knowledge and understanding of the history of our
universe. The precision of the CMB observations has enabled us to show the blackbody
nature of the spectrum of this remnant radiation with a great accuracy. However, any form of
energy injected into CMB at redshifts between 103 and 106 could cause deviation from the
perfect blackbody spectrum. Such a signature serves as a powerful probe of physical
processes in the universe during that period before the last scattering of photons. In this
context, we investigate the mechanism of production of massless spin-1 particles through
their coupling to axion-like fields. The (possibly abundant) presence of axions is generically
expected in any UV-complete theory, and they interact with gauge fields in a unique way due
to their symmetries. We consider the consequence of this interaction and show that coherent
oscillation of axions leads to copious production of gauge quanta in the early universe. The
produced energy can disturb the blackbody nature of the CMB spectrum before
recombination, resulting in spectral distortions. We evaluate the signals of this effect, in view
of forthcoming missions such as PIXIE that are expected to improve their spectral sensitivity
by as much as 3 orders of magnitude.