Thermal Sunyaev-Zel'dovich effect in the intergalactic medium with primordial magnetic fields
Abstract
The presence of ubiquitous magnetic fields in the universe is suggested from observations of radiation and cosmic ray from galaxies or the intergalactic medium (IGM). One possible origin of cosmic magnetic fields is the magnetogenesis in the primordial universe. Such magnetic fields are called primordial magnetic fields (PMFs), and are considered to affect the evolution of matter density fluctuations and the thermal history of the IGM gas. Hence the information of PMFs is expected to be imprinted on the anisotropies of the cosmic microwave background (CMB) through the thermal Sunyaev-Zel'dovich (tSZ) effect in the IGM. In this study, given an initial power spectrum of PMFs as P (k )∝B1Mpc 2knB , we calculate dynamical and thermal evolutions of the IGM under the influence of PMFs, and compute the resultant angular power spectrum of the Compton y -parameter on the sky. As a result, we find that two physical processes driven by PMFs dominantly determine the power spectrum of the Compton y -parameter; (i) the heating due to the ambipolar diffusion effectively works to increase the temperature and the ionization fraction, and (ii) the Lorentz force drastically enhances the density contrast on small scale just after the recombination epoch. These facts result in making the anisotropies of the CMB temperature on small scales, and we find that the signal goes up to 10 μ K2 around ℓ∼106 with B1 Mpc=0.1 nG and nB=0.0 . Therefore, CMB measurements on such small scales may provide a hint for the existence of the PMFs.
- Publication:
-
Physical Review D
- Pub Date:
- December 2017
- DOI:
- 10.1103/PhysRevD.96.123525
- arXiv:
- arXiv:1705.10054
- Bibcode:
- 2017PhRvD..96l3525M
- Keywords:
-
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies;
- High Energy Physics - Phenomenology
- E-Print:
- 10 pages, 3 figures, 1 table, published in PRD