Correlating Non-linear Structure in 21cm Intensity Maps with Photometric Surveys

Albert Stebbins (Fermilab)

Correlating Non-linear Structure in 21cm Intensity Maps with Photometric Surveys


Hydrogen Intensity Mapping Surveys should provide maps of the neutral hydrogen over verylarge cosmological volumed out to redshifts of 2 or greater. These surveys will typically have very poor angular resolution (say 10’), but can have superb redshift resolution. In contrast, photometric galaxy surveys such as LSST have superb angular resolution but relatively poor redshift resolution, without spectroscopic follow-up. Can one combine the two in order to find precise redshift of individual galaxies or galaxy groups discovered by LSST? While a naive linear theory analysis says no, if one integrates long enough, the HI surveys will reveal non-linear structures which can be
associated with structures found in photometric redshift surveys, giving them a precise redshift, but with limited confidence.

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