| Authors Affiliation: | Soumil Maulick, Kanak Saha (Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Post Bag 4, Pune 411007, India)
Akio K. Inoue (Faculty of Science and Engineering, Waseda Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555,
Japan)
Akio K. Inoue (Faculty of Science and Engineering, Department of Physics, School of Advanced Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo
169-8555, Japan) |
| Abstract : | We report the tentative detection (greater than 3 sigma significance) of LyC photons from the edge of cosmic reionization. The signal is detected on a stack of seven redshift greater than 6 objects, six of which are confirmed Lyman-alpha emitters (LAEs), with the stacking analysis being carried out in the near-ultraviolet (1700-3050A) N242W band of the UVIT telescope on AstroSat. In the rest-frame, this corresponds to a detection of extreme-UV (EUV) photons at a rest-frame wavelength of about 330A. Using available JWST and MUSE spectroscopic data in conjunction with the N242W signal, we provide the first direct constraint on the escape fraction of ionizing photons at this redshift, while keeping in mind possible ramifications of detection at rest-frame wavelength of 330A, rather than at 900A, which is typically used for LyC studies in the literature. We estimate that at least 24-44 percent of ionizing photons are able to escape these objects and can contribute to the ionization of the inter-galactic medium (IGM). This is larger than typically measured escape fraction values at lower redshifts and than what is predicted using either indirect tracers or as inputs in simulations. We find that current IGM models pose a challenge in explaining such a detection because of the high optical depth such photons are expected to face.
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