Reionization marks the last major phase transition of matter in the Universe and its completion had crucial impact on the formation of the smallest galaxies. While reionization roughly encapsulated the first Gyr of cosmic time, the precise timing, topology and the sources of ionizing photons are unknown. In my talk, I will mainly present results on the spectroscopic properties of galaxies in...
A key unknown in our understanding of cosmic reionization is the feedback mechanisms that enabled Lyman continuum (LyC) to escape in the earliest starbursts. One clue comes from Green Pea (GP) galaxies, the largest class of local (z ~ 0.3) LyC emitters. Most GPs show broad nebular emission-line wings of unknown origin, reaching 200-1000 km/s. The broad-wing velocity has been shown to correlate...
The Sunburst Arc (z~2.37) is a confirmed Lyman continuum leaker galaxy and has been uniquely lensed where its single leaking region is imaged 12 times over four separate arcs. Using HST/WFC3 UVIS G280 grism observations, we extracted the spectra of the leaking region to determine the shape of the stellar continuum from 600-900Å (produced by young, massive O and B stars) for the first time. The...
The opacity of the intergalactic medium does not allow a direct measurement of Lyman continuum (LyC) emission at redshifts exceeding 4.5. Consequently, we are increasingly relying on indirect indicators of LyC emission that are well tested at low and intermediate redshift. In this study, we use several such indirect indicators, based on parameters like UV-beta slope, E(B-V), UV magnitude, and...
Low mass galaxies are one of the main sources of Lyman continuum (LyC) photons, which ionized the intergalactic medium during cosmic reionization. However, the escape fraction of LyC photons from these galaxies depends on the properties and dynamics of the neutral gas that surrounds the star-forming regions. Galactic mergers can affect both the star formation rate and the gas distribution...
Measurements of the ionizing background and the mean free path (MFP) at the end of reionization offer valuable insights into the first generation of sources that ionized the universe. With increasing observational data from this epoch, a better theoretical understanding is imperative to interpret the data accurately.
The CROC simulations are uniquely poised to interpret observational data,...
The Epoch of Reionisation (EoR) was the period of the Universe during which the neutral hydrogen present in the intergalactic medium (IGM) was ionised by Ultraviolet radiation from sources inside early galaxies. Significant progress has been made in modelling cosmic reionisation through numeric and semi-numeric codes. However, the end of reionisation has been studied less. In radiative...
