AstroSat detection of Lyman Continuum emission from a z=1.42 galaxy

Kanak Saha, Shyam N. Tandon, Charlotte Simmonds, Anne Verhamme, Abhishek Paswan, Daniel Schaerer, Michael Rutkowski, Anshuman Borgohain, Bruce Elmegreen, Akio K. Inoue, Francoise Combes, Debra Elmegreen, Mieke Paalvast

Research output: Contribution to journalArticlepeer-review


One of the outstanding problems of current observational cosmology is to understand the nature of sources that produced the bulk of the ionizing radiation after the Cosmic Dark Age. Direct detection of these reionization sources1 is practically infeasible at high redshift due to the steep decline of intergalactic medium transmission2,4. However, a number of low-redshift analogs emitting Lyman continuum at 900Å restframe are now detected at z < 0.4 [5, 6, 7, 8, 9] and there are detections in the range 2.5 < z < 3.5 [10, 11, 12, 13, 14, 15] also. Here, we report the detection of Lyman continuum emission with a high escape fraction (¿20%) from a low-mass clumpy galaxy at z=1.42, in the middle of the redshift range where no detection has been made before and near the peak of the Cosmic Star-formation history16. The observation was made in the Hubble Extreme Deep field17 by the wide-field Ultra-Violet-Imaging Telescope18 on-board AstroSat19. This is the first detection of Extreme Ultraviolet radiation from a distant galaxy at a rest-frame wavelength of 600, and it opens up a new window to constrain the shape of the ionization spectrum. Further observations with AstroSat should significantly increase the sample of Lyman continuum leaking galaxies at Cosmic Noon.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - 2020 Aug 26

ASJC Scopus subject areas

  • General

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