Schematic Pictures of An Analysis Scheme (IMAGE)
Caption
Schematic pictures of an analysis scheme of previous work (left) and a new method (right). In the previous approach, basically a single background light source (quasar) can be used in a searched area. On the other hand, with the new scheme, it is easier to spatially resolve the neutral hydrogen gas density by using many normal galaxies in a searched area as background light sources. In the new scheme, absorption strength by the neutral hydrogen gas is estimated by measuring how much flux of the background galaxies becomes dimmed in the narrow-band image, not by using spectrum. By combining this scheme with the wide-area imaging ability of the Subaru Telescope, Mawatari, et al. made the most-extensive map of neutral hydrogen gas ever created.
Credit
Credit: Osaka Sangyo University / NAOJ
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