Day 1351

Wednesday.

1712.03986
Can gravitational microlensing detect extragalactic exoplanets?  Self-lensing models of the Small Magellanic Cloud
Mroz, Poleski

Use 3D distributions of classical Cepheids and RR Lyrae stars in SMC to model the stellar density distribution of a young and old stellar population in that galaxy.  Use these models to estimate the microlensing self-lensing optical depth to the SMC, which is in excellent agreement with the observations.  Thus, estimate the total stellar mass of the SMC of about 1.0e9Msun under assumption that all microlensing events toward this galaxy are caused by self-lensing.  Also calculate the expected event rates and estimate that future large-scale surveys, like the LSST, will be able to detect up to a few dozen microlensing events in the SMC annually.  If the planet frequency in the SMC is similar to that in the MW, a few extragalactic planets can be detected over the course of the LSST survey, provided significant changes in the SMC observing strategy are devised.  A relatively small investment of LSST resources can give a unique probe of the population of extragalactic exoplanets.


1712.03997
The extended Baryon Oscillation Spectroscopic Survey (eBOSS): testing a new approach to measure the evolution of the structure growth
Ruggeri, Percival, Mueller, Gil-Marin, Zhu, Padmanabhan, Zhao

eBOSS is one of the first of a new generation of galaxy z surveys that will cover a large range in z with sufficient resolution to measure the BAO signal.  For surveys covering a large redshift range, cosmological evolution can no longer be ignored, meaning that either the z shells analyzed have to be significantly narrower than the survey, or averaging over evolving quantities must be allowed.  Both have the potential to remove signal: analyzing small volumes increases the size of the Fourier window function, reducing the large-scale information, while averaging over evolving quantities can, if not performed carefully, remove differential information.  It will be important to measure cosmo evolution from these surveys to explore and discriminate between models.  Apply a method to optimally extract this differential information to mock catalogues designed to mimic the eBOSS quasar sample.  By applying a set of weights to extract z space distortion measurements as a function of z, demonstrate an analysis that does not invoke the problems discussed above.  Show that the estimator gives unbiased constraints.