Detecting z > 10 objects through carbon, nitrogen, and oxygen emission lines

By redshift z = 10, star formation in the first objects should have produced considerable amounts of carbon, nitrogen, and oxygen. The submillimeter lines of C, N, and O redshift into the millimeter and centimeter bands (0.5 mm-1.2 cm), where they may be detectable. High spectral resolution observations could potentially detect inhomogeneities in C, N, and O emission, and see the first objects forming at high redshift. We calculate expected intensity fluctuations and discuss frequency and angular resolution required to detect them. For C II emission, we estimate the intensity using two independent methods: the line-emission coefficient argument and the luminosity-density argument. We find they are in good agreement. At 1 + z ∼ 10, the typical protogalaxy has a velocity dispersion of 30 km s^-1 and an angular size of 1″. If C II is the dominant coolant, then we estimate a characteristic line strength of ∼0.1 K km s^-1. We also discuss other atomic lines and estimate their signal. Observations with a frequency resolution of 10^-3 can detect moderately nonlinear fluctuations of amplitude 2 × 10^-5 times the microwave background. If the intensity fluctuations are detected, they will probe matter density inhomogeneity, chemical evolution, and ionization history at high redshifts.