We compute the effect of local electrons on the CMB temperature anisotropics. The number density and distribution of free electrons in our Galaxy has been accurately measured from pulsar dispersion measurements. Because of their distribution, the dynamics of our Galaxy, and the Galaxy peculiar velocity with respect to the Hubble flow, these free electrons leave a frequency-independent imprint on the cosmic microwave background (CMB). In particular, the coherent motion of the free electrons with respect to us and to the CMB rest frame produce a kinetic Sunyaev-Zel'dovich signal. We compute this effect and we note that the large-scale antisymmetry of the signal gives it an angular power spectrum with a sawtooth pattern, where even multipoles are suppressed with respect to the odd ones. We find the signal to be small (&slim2 μK) and subdominant compared to the primary CMB and other foreground signals. However, since the parameters of this model are constrained by other independent astrophysical observations, it can be taken into account if more precise measurements of the primordial signal are required.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Cosmic microwave background
- Galaxy: kinematics and dynamics