Monday, 3:10 PM — MP1318A

The presence of liquid water has been hypothesized as an important ingredient for planet habitability. A sub-Neptune mass planet with a liquid water ocean below a hydrogen-rich envelope is an intriguing prospect. If the planet transits, its atmosphere could be amenable to characterization with transmission spectroscopy. A practical method to assess whether a transiting sub-Neptune planet could potentially harbour a liquid water ocean is needed. With interior structure models, I explore the conditions needed to reach pressures and temperatures conducive to liquid water at the planet surface. I apply this approach to constrain the prospects for liquid water oceans on GJ1214b and Kepler-22b.

Thursday, 11:10 AM — MP1318A

Colgate and White (1966) were the first to propose that core-collapse supernovae may be neutrino-driven and per formed the first numerical simulations of such events, launching more than four decades of research that continues to this day. In the time since, many authors have explored the impact of moving beyond the spherically-symmetric assumptions of Colgate & White (cf. Nordhaus et al. 2011) by performing simulations in 2 and 3 dimensions. Neutrino transport and spatial dimensionality continue to be among the primary limitations on physical fidelity in core-collapse supernova simulations, even on today's petascale platforms. We have recently conducted a series of numerical experiments to examine the effects of several approximations used in multidimensional core-collapse supernova simulations. I will describe some of the results of these studies, including what approximations seem unrealistic and which are required for any future simulations if they hope to be definitive in any sense.

Thursday, 3:10 PM — MP1318A

The isotropy of CMB is one of the important tests of the modern cosmology. I am going to discuss the current and prospective tests of statistical anisotropy in the CMB:
(1) “Copi etal. (2009)” have been arguing that the lack of large angular correlations of the CMB temperature field provides strong evidence against the standard, statistically isotropic, LCDM cosmology. I am going to argue that the “ad-hoc” discrepancy is due to the sub-optimal estimator of the low-l multipoles, and a posteriori statistics, which exaggerates the statistical significance. Therefore there is no actually lack of angular correlation in the CMB.
(2) I construct simple quadratic estimators to reconstruct asymmetry in the primordial power-spectrum from CMB temperature and polarization data and verify their accuracy using simulations with quadrupole power asymmetry. I show that the Planck mission, with its millions of signal dominated modes of the temperature anisotropy, should be able to constrain the amplitude of any spherical multipole of a scale-invariant quadrupole asymmetry at the 0.01 level (2 sigma).
(3) LCDM model also predict the existence of primordial gravitational wave, for which B-mode polarization will be a powerful tool to distinguish different models of the early Universe.

In addition, I will discuss the Planck mission launched by European Space Agency in May/2012 to observe the CMB anisotropy, and its prospective scientific impact on precision cosmology.