Publication Date:
2015-07-18
Description:
Strong gravitational lensing provides some of the deepest views of the Universe, enabling studies of high-redshift galaxies only possible with next-generation facilities without the lensing phenomenon. To date, 21-cm radio emission from neutral hydrogen has only been detected directly out to z ~ 0.2, limited by the sensitivity and instantaneous bandwidth of current radio telescopes. We discuss how current and future radio interferometers such as the Square Kilometre Array (SKA) will detect lensed H i emission in individual galaxies at high redshift. Our calculations rely on a semi-analytic galaxy simulation with realistic H i discs (by size, density profile and rotation), in a cosmological context, combined with general relativistic ray tracing. Wide-field, blind H i surveys with the SKA are predicted to be efficient at discovering lensed H i systems, increasingly so at z 2. This will be enabled by the combination of the magnification boosts, the steepness of the H i luminosity function at the high-mass end, and the fact that the H i spectral line is relatively isolated in frequency. These surveys will simultaneously provide a new technique for foreground lens selection and yield the highest redshift H i emission detections. More near term (and existing) cm-wave facilities will push the high-redshift H i envelope through targeted surveys of known lenses.
Print ISSN:
1745-3925
Electronic ISSN:
1745-3933
Topics:
Physics
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