Speaker: Anoma Ganguly, Tata Institute of Fundamental Research, Mumbai, India
Date/Time: December 1, 2023 / 12 noon central.
Location: NCSA, 1040.
Zoom: https://illinois.zoom.us/j/82318062756?pwd=M3g1MFF6cytsOWFEbmU0UW1XWVoxQT09
Title: Rich cosmological signatures of composite dark matter.
Abstract: We propose a new method to search for dark matter using dark forest/absorption features across the full electromagnetic spectrum, especially in the bands where there is a desert i.e. regions where no strong lines from baryons are expected. These unique signatures can arise for dark matter models with a composite nature and internal electromagnetic transitions. In the presence of a background source, such as a quasar, such interactions in the dark matter halos can produce a series of closely spaced absorption lines, which we call the dark forest. The dark forest feature is a sensitive probe of the dark matter self-interactions and the halo mass function, especially at the low mass end. There is a large volume of parameter space where dark forest is more sensitive compared to the best current and proposed direct detection experiments. Further, the electromagnetic transitions in dark matter due to CMB photons can give rise to unique features in the spectrum of the CMB. In particular, dark matter transition energies ~10^{-4} eV can produce a global absorption signal in the CMB which is consistent with the anomalous absorption feature detected by the EDGES collaboration.
