Day 1271

Thursday.


1706.04201
Formation of hypervelocity stars in AGN outflows
Wang, Loeb

Study SF within outflows driven by AGN as a new source of hypervelocity stars (HVSs).  Recent observations revealed active SF inside a galactic outflow at a rate of ~15 Msun/yr.  Show that the shells swept up by an AGN outflow are capable of cooling and fragmentation into cold clumps embedded in a hot tenuous gas via thermal instabilities.  As a result, stars are produced along outflow's path, endowed with the outflow speed at their formation site.  These HVSs travel through the galactic halo and eventually escape into the IGM.  The expected instantaneous rate of SF inside the outflow is ~4-5 orders of magnitude greater than the average rate associated with previously proposed mechanisms for producing HVSs, such as the Hills mechanism and 3-body interaction between a star and a BH binary.


1706.04583
Cosmological constraints from a joint analysis of cosmic microwave background and large-scale structure
Doux, et al

The standard model of cosmology, LCDM, is the simplest model that matches the current observations, but relies on 2 hypothetical components, to wit, dark matter and dark energy.  Further galaxy surveys and CMB experiments will independently shed light on these components, but a joint analysis that includes cross-correlations will be necessary to extract as much information as possible from the observations.  In this paper, aim at developing the methods needed to perform such an analysis, and test it on publicly available data sets.  In particular, use CMB temperature anisotropies and CMB lensing observations from Planck, and the spectroscopic galaxy and quasar samples of SDSS-III/BOSS.  Build a likelihood to simultaneously analyze the auto and cross spectra of the CMB lensing and the galaxy overdensity maps before running MCMC to assess the constraining power of the combined analysis.  Then add CMB temperature information and run MCMCs to test the LCDM model.  Present constraints on cosmo parameter and galaxy biases, and demonstrate that the joint analysis can additionally constrain the mass of neutrinos as well as the DE EoS.  Finally, discuss several difficulties regarding the analysis itself and the theoretical precision of the models, which will require additional work to properly analyse the observations of the next generation of cosmo experiments.