The 21cm bispectrum as a probe of non-Gaussianities due to X-ray heating

Understand

We present analysis of the normalised 21-cm bispectrum from fully-numerical simulations of intergalactic-medium heating by stellar sources and high-mass X-ray binaries (HMXB) during the cosmic dawn.

• Lyman-$\alpha$ coupling is assumed to be saturated, we therefore probe the nature of non-Gaussianities produced by X-ray heating processes.
• We find the evolution of the normalised bispectrum to be very different from that of the power spectrum.
• It exhibits a turnover whose peak moves from large to small scales with decreasing redshift, and corresponds to the typical separation of emission regions.