Day 652

Saturday.

1401.6456
A rapid evolving region in the galactic center: why S-stars thermalize and more massive stars are missing
Chen, Amaro-Seoane

The observed population of "S-stars" within a distance of 1" from SgrA* contradicts the understanding of star formation, due to the forbiddingly violent environment.  A suggested possibility is that these stars form far and have been brought by some fast dynamical process, since they are young.  Nonetheless, all conjectured mechanisms either fail to reproduce their eccentricities -- without resorting to extra ingredients, which render the models more complicated -- or cannot explain the problem of "inverse mass segregation" at the Galactic Center: the fact that lighter stars are closer to the center (the S-stars) and more massive ones, WR and O-stars, father out.  In this Letter, put forward the idea that the responsible for both, the distribution of the eccentricities and the paucity of massive stars, in an induced Kozai-Lidov-like resonance exerted by the observed disk on the stars populating the innermost 1" region, considering that the disk probably extended to smaller radius in the past.

1401.6459
The Local Void: for or against $\Lambda$CDM?
Xie, Gao, Guo

The emptiness of the Local Void has been put forward as a serious challenge to the current standard paradigm of structure formation in LCDM.  Use a high resolution cosmological N-body sim, the Millennium-II run, combined with a sophisticated SAM, to explore statistically whether the local void is allowed within the current knowledge of galaxy formation in LCDM.  Find that about 15% of the LG analogue systems (11 of 77) in the simulation are associated with nearby low density regions having size and 'emptiness' similar to those of the observed Local Void.  This suggests that, rather than a crisis of the LCDM, the emptiness of the Local Void is indeed a success of the standard LCDM theory.  The paucity of faint galaxies in such voids results from a combination of two factors: a lower amplitude of the halo mass function in the voids than in the field, and a lower galaxy formation efficiency in void haloes due to halo assembly bias effects.  While the former is the dominating factor, the latter also plays a sizable role.  The halo assembly bias effect results in a stellar mass fraction 25% lower for void galaxies when compared to field galaxies with the same halo mass.

1401.6842
3d cosmic shear: cosmology from CFHTLenS
Kitching et al

Present the first application of 3d cosmic shear to a wide-field WL survey.  3d cosmic shear is a technique that analyses WL in 3d using a spherical harmonic approach, and does not bin data in the redshift direction.  This is applied to CFHTLenS, a 154 square degree imaging survey wit ha median redshift of 0.7 and an effective number density of 11 galaxies per square arc minute usable for WL.  To account for survey masks, apply a 3d pseudo-Cl approach on WL data, and to avoid uncertainties in the highly NL regime, separately analyze radial wave numbers k<=1.5h/Mpc and k>=5.0h/Mpc, and angular wave numbers l~400-5000.  Show how one can recover 2d and tomographic PS from the full 3d cosmic shear PS and present a measurement of the 2d cosmic shear power spectrum, and measurements of a set of 2-bin and 6-bin cosmic shear tomographic PS; in doing so, find that using the 3d power in the calculation of such 2d and tomographic PS from data naturally accounts for a minimum scale in the matter PS.  Use 3d cosmic shear to constrain cosmologies with parameters OmegaM, OmegaB, sigma8, h, ns, w0, wa.  For a non-evolving DE EoS, and assuming a flat cosmology, lensing combined with WMAP7 results in h=0.78pm0.12, OmeagM=0.252pm0.079, sigma8=0.88pm0.23, and w=-1.16pm0.38 using only scales k<=1.5h/Mpc.  Also present results of lensing combined with first year Planck results, where no tension is found with the results form this analysis, but also find no significant improvement over the Planck results alone.  Find evidence of a suppression of power compared to LCDM on small scales 1.5<k<=5.0h/Mpc in the lensing data, which is consistent with predictions of the effect of baryonic feedback on the matter PS.