A novel approach for measuring the escape of ionizing radiation from Lyman Alpha emitting galaxies

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2023-12

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How the bulk, intergalactic gas of the universe came to be nearly fully ionized after its earlier neutral state following the Epoch of Recombination remains an open investigation. That this (re)ionization took place between roughly z ∼ 15 and z ∼ 6 via photoionization is well accepted, but the main sources of the ionizing photons is actively debated. Star-forming galaxies are frequently suggested as the most likely driver. However, direct measurements of ionizing radiation from such galaxies in the Epoch of Reionization is not possible and existing surveys of what are thought to be similar, lower redshift galaxies have inconsistent or incompatible results due partly to their necessary methodologies and comparatively small sample sizes. In this work, I seek to address these issues. This dissertation represents an exploratory work to determine if it is possible to algorithmically identify large numbers of Lyman Alpha Emitting galaxies from the many millions of untargeted, low resolution spectra from the Hobby-Eberly Telescope Dark Energy Experiment survey and through spectral stacking measure the average escaping Lyman Continuum flux and various other physical properties of those galaxies. These small, rapidly star-forming, low-metallicity, z ∼ 3 galaxies can then be used as better proxies for higher redshift, Epoch of Reionization analogs and determine what role they may have played in the reionization of the universe.

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