First Star Signature in Infrared Background Anisotropies

(Abridged) Recent cosmic microwave background anisotropy results from theWilkinson Microwave Anisotropy Probe suggest that the universe was reionized ata redshift around 20. Such an early reionization could arise through theionizing radiation emitted by metal-free population III stars at redshifts of10 and higher. We discuss infrared background (IRB) surface brightness spatialfluctuations from such a generation of early star formation. We show that thespatial clustering of these stars at tens of arcminute scales generates acontribution to the angular power spectrum of the IRB anisotropies at the sameangular scales. This excess can be potentially detected when resolvedforeground galaxies out to a redshift of a few is removed from the clusteringanalysis. Additionally, assuming a population III stellar spectrum, we suggestthat the clustering excess related to the first generation of stars can beseparated from brightness fluctuations resulting from other foreground sourcesand galaxies using multifrequency observations in the wavelength range of ~ 1to 5 microns. In addition to removing the low-redshift galaxy population, themultifrequency data are essential to account for certain foregroundcontaminants such zodiacal light, which, if varying spatially over degreescales, can be a significant source of confusion for the proposed study. Usingvarious instruments, we study the extent to which spatial fluctuations of theIRB can be studied in the near future.Comment: 15 pages, 7 figures; Version to appear in the Astrophysical Journa