Microwave Background Anisotropies Due to the Kinematic Sunyaev-Zeldovich Effect of the Lyα Forest

Abstract

The Ly alpha absorption systems observed in the spectra of QSOs are likely to possess bulk peculiar velocities. The free electrons in these systems scatter the microwave background and distort its spectrum through the kinematic Sunyaev-Zeldovich effect. I calculate the temperature fluctuations of the microwave sky due to variations in the number of Ly alpha systems along different lines of sight throughout the universe. The known population of absorbers out to z approximate to 5 introduces anisotropies on angular scales less than or similar to 1' with an rms amplitude of order Delta T/T approximate to 10(-6)(Omega(Ly alpha)/0.05) <nu(400)(2)>(1/2), where Omega(Ly alpha) is the cosmological density parameter of ionized gas in Ly alpha absorption systems, and <nu(400)(2)>(1/2) is the rms line-of-sight peculiar velocity of these systems at z similar to 3 in units of 400 km s(-1). Detection of this signal will provide valuable information about the cosmic velocity held and the gas content of Ly alpha absorption systems at high redshifts.