Abstract
The Lyα 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 Lyα systems along different lines of sight throughout the universe. The known population of absorbers out to z ≈ 5 introduces anisotropies on angular scales 1' with an rms amplitude of order ΔT/T ≈ 10-6Lyα/0.05) v24001/2, where ΩLyα is the cosmological density parameter of ionized gas in Lyα absorption systems, and v24001/2 is the rms line-of-sight peculiar velocity of these systems at z ~ 3 in units of 400 km s-1. Detection of this signal will provide valuable information about the cosmic velocity field and the gas content of Lyα absorption systems at high redshifts.
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