Alonso, DavidFerreira, Pedro G.Jarvis, MattMoodley, Kavilan2017-09-272017-09-272017Alonso, D. et al. (2017). Calibrating photometric redshifts with intensity mapping observations. Physical Review D, 96: 0435152470-0010http://dx.doi.org/10.1103/PhysRevD.96.043515http://hdl.handle.net/10566/3210Imaging surveys of galaxies will have a high number density and angular resolution yet a poor redshift precision. Intensity maps of neutral hydrogen (HI) will have accurate redshift resolution yet will not resolve individual sources. Using this complementarity, we show how the clustering redshifts approach, proposed for spectroscopic surveys can also be used in combination with intensity mapping observations to calibrate the redshift distribution of galaxies in an imaging survey and, as a result, reduce uncertainties in photometric redshift measurements. We show how the intensity mapping surveys to be carried out with the MeerKAT, HIRAX and SKA instruments can improve photometric redshift uncertainties to well below the requirements of DES and LSST. The effectiveness of this method as a function of instrumental parameters, foreground subtraction and other potential systematic errors is discussed in detail.enThis is the pre-print version of the article published online at: http://dx.doi.org/10.1103/PhysRevD.96.043515Photometric redshiftsIntensity mappingGalaxiesMeerKATHIRAXSKAArticle