Center for Theoretical Physics of the Universe (CTPU-PTC)

Cosmological Particle Productions and Pairwise Hotspots on the CMB

by Jeong Han Kim (Chungbuk National University)

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When heavy particles are pair produced during inflation via couplings to the inflaton, the particle mass modifies the surrounding curvature perturbation in a time-dependent manner and generates a non-trivial curvature profile in position space at the end of inflation. Even if the heavy particles no longer exist, the modified curvature perturbations are preserved before horizon re-entry and will generate localized hot or cold spots on the CMB. By studying the signals of pairwise spots, we can probe extremely heavy particles with masses comparable to the inflationary energy scale. We explore the phenomena by assuming the heavy particle to be produced by a scalar field that couples to inflaton. We study the non-adiabatic particle production of the heavy particle during the inflation and show that the resulting temperature profile generates pairwise hotspots (PHS) on the CMB map from a combination of the induced curvature perturbation and the transfer function of ΛCDM fluids. When the heavy scalar has an O(1) coupling to the inflaton, we show that in an idealized situation where the dominant background of the PHS signal comes from the CMB fluctuations, a position space search based on the temperature and number density cuts of the hotspot signals can be sensitive to heavy scalar masses M0 being comparable to inflaton’s kinetic energy and M0/H∗ = O(100) for the Hubble H∗ during inflation. The corresponding PHS signal also modified the CMB power spectra and bispectrum, although the corrections are below the sensitivity of current measurements.