= Kinetic Sunyaev-Zeldovich effect
{title2=$\Delta T/T=-\tau v_{\parallel}/c$}
Bulk motion of a scattering electron cloud relative to the <cosmic microwave background> gives a first-order Doppler <temperature> shift. With positive $v_{\parallel}$ directed away from the observer, the displayed sign applies, and $\tau$ is the <Thomson scattering> <optical depth>. In the nonrelativistic, single-scattering limit it has the spectrum of a small <blackbody> temperature change, unlike the <thermal Sunyaev-Zeldovich effect>.
Back to article page
