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UBC Theses and Dissertations

Improving optical photo-𝒛 estimates using submillimetre photometry Tanouri, Pouya


Estimating the redshifts of distant galaxies is critical for determining their intrinsic properties, as well as for using them as cosmological probes. Measuring redshift spectroscopically is accurate, but expensive in terms of telescope time. Hence it has become common to use “photometric redshifts”, which are fits to photometry taken in a number of filters, using templates of galaxy spectral energy distributions. However, most methods rely on photometry only in the optical and near-IR wavebands, neglecting longer wavelength data. Since the ultimate goal is to obtain redshift estimates for all galaxies, it is important to improve photo-𝒛s for the sources where optical/NIR fits fail to produce reliable results. For specific subsets of galaxies, in particular dusty starbursts, it can be particularly hard to obtain good photo-𝒛 estimates, while these same galaxies are often bright at longer wavelengths. Here we describe how to add information from far-IR to millimetre photometry to help improve the photo-𝒛 estimates for the dustiest and most actively star-forming galaxies.

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