Sunyaev-Zeldovich fluctuations from the first stars?
WMAP's detection of high electron-scattering optical depth τe suggests substantial star formation at high redshift z∼ 17 ± 5. On the other hand, the recovered σ8∼ 0.84 ± 0.04 argues against a cluster Sunyaev–Zeldovich (SZ) origin for the observed small-scale cosmic microwave background (CMB) fluctuation excess, which generally requires σ8∼ 1.1. Here we consider the effects of high-redshift star formation on the CMB. We derive a fairly model-independent relation between τₑ and the number of ionizing photons emitted per baryon Nᵧ, and use this to calibrate the amount of high-redshift supernova activity. The resulting supernova remnants Compton cool against the CMB creating a Compton y distortion y∼ few × 10⁻⁶ within observational bounds. However they also create small-scale SZ fluctuations, which could be comparable with SZ fluctuations from unresolved galaxy clusters. This raises the exciting possibility that we have already detected signatures of the first stars not just once, but twice, in the CMB.
Additional Information© 2003 RAS. Accepted 2003 April 11. Received 2003 April 16; in original form 2003 March 7. This work was supported by NASA NAG5-9821 and DoE DE-FG03-92-ER40701.
Published - 342-1-L20.pdf
Submitted - 0303007.pdf