star shades, data-driven redshifts

In a day limited by health issues, I had a useful conversation with Leslie Greengard and Alex Barnett (SCDA, Dartmouth) about star-shades for nulling starlight in future exoplanet missions. They had ideas about how the electromagnetic field might be calculated, and issues with what might be being done with current calculations of this. These calculations are hard, because the star-shades under discussion for deployment at L1 are many times 107 wavelengths in diameter, and millions of diameters away from the telescope!

I also talked to Boris Leistedt about galaxy and quasar cosmology using imaging (and a tiny bit of spectroscopy), in which the three-dimensional mapping is performed with photometric redshifts, or more precisely models of the source spectral energy distributions that are modeled simultaneously with the density field and so on. We are working on a first paper with recommendations for LSST. The idea is that a small amount of spectroscopy and an enormous amount of imaging ought to be sufficient to build a model that returns a redshift and spectral energy distribution for every source.

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