Abstract:
One of the outstanding problems of current observational cosmology is to understand the nature of sources that produced the ionizing radiation after the Cosmic Dark Age. Due to the steep decline of intergalactic medium transmission, direct detection of these reionization sources is difficult at high redshift. The FUV band of the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat with rest-frame Lyman limit of hydrogen at 912 Å from z ∼ 0.97, is ideally suited for such detections. In this presentation, I will talk about the Lyman continuum (LyC) emitters detected at redshift z ~ 1.2-1.6 in the Astrosat Ultradeep Deep Field North (AUDFn) using UVIT. This was the first coherent sample of LyC leakers at z ∼1-2 as there were no direct detections at z ∼ 0.5 - 3 earlier. This research bridges the gap between GALEX and Cosmic Origins Spectrograph (COS) at low-z, and HST WFC3 at high-z and stands crucial in understanding the evolution of LyC leakers. These sources emitting Extreme Ultraviolet radiation at a rest-frame wavelength of ~600 Å would be essential in constraining the shape of the ionization spectrum. I will discuss the properties of the LyC leakers sample as obtained from the Spectral Energy Distribution fitting and spectroscopic analysis, particularly the UV continuum slopes (β) and rest-frame optical emission-line diagnostics to probe the physical conditions governing LyC leakage.
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