122 citations · 1k across the 49 of their papers we have counts for
6 papers · 1 filter
Axionic defects in the CMB: birefringence and gravitational waves
Ricardo Z. Ferreira, Silvia Gasparotto, Takashi Hiramatsu +2
The evidence for a non-vanishing isotropic cosmic birefringence in recent analyses of the CMB data provides a tantalizing hint for new physics. Domain wall (DW) networks have recen…
Can we explain cosmic birefringence without a new light field beyond Standard Model?
Yuichiro Nakai, Ryo Namba, Ippei Obata +2
The recent analysis of the Planck 2018 polarization data shows a nonzero isotropic cosmic birefringence (ICB) that is not explained within the CDM paradigm. We then explore the…
Parity-violating scalar trispectrum from a rolling axion during inflation
Tomohiro Fujita, Tomoaki Murata, Ippei Obata +1
We study a mechanism of generating the trispectrum (4-point correlation) of curvature perturbation through the dynamics of a spectator axion field and U(1) gauge field during infla…
Axion-Gauge Dynamics During Inflation as the Origin of Pulsar Timing Array Signals and Primordial Black Holes
Caner Unal, Alexandros Papageorgiou, Ippei Obata
We demonstrate that the recently announced signal for a stochastic gravitational wave background (SGWB) from pulsar timing array (PTA) observations, if attributed to new physics, i…
Cosmic birefringence tomography with polarized Sunyaev Zel'dovich effect
Toshiya Namikawa, Ippei Obata
We consider the polarized Sunyaev-Zel'dovich (pSZ) effect for a tomographic probe of cosmic birefringence, including all relevant terms of the pSZ effect in the cosmic microwave ba…
First results of axion dark matter search with DANCE
Yuka Oshima, Hiroki Fujimoto, Jun'ya Kume +7
Axions are one of the well-motivated candidates for dark matter, originally proposed to solve the strong CP problem in particle physics. Dark matter Axion search with riNg Cavity E…