Day 355

Sunday.

1212.2985
First astroseismic limits on the nature of dark matter
Casanellas, Lopes

Weakly interacting low-mass DM particle constraints; the additional energy transport mechanism due to accumulated asymmetric DM particles modifies the central temperature and density of low-mass stars and suppresses the convective core expected in 1.1-1.3 Ms stars even for an environmental DM density as low as the expected in the solar neighborhood.  Compare to a few stars modeled astroseismically, rule out region of DM parameter space mass vs. spin-dependent DM-proton scattering cross section comparable with present experimental constraints.

1212.3082
The Planck Sunyaev-Zel'dovich vs. the X-ray view of the Coma cluster
Fusco-Femiano, Lapi, Cavaliere

Planck directly gauged the e- pressure profile in intracluster plasma from SZ effect, of Coma cluster.  This quantity may also be derived by combining the density and temperature provided by X-ray observations of the thermal bremsstrahlung radiation emitted by the plasma.  Find a model-independent tension between the SZ and the X-ray pressure, with the SZ one being definitely lower by 15-20%.  Propose that such a challenging tension can be resolved in terms of an additional, non-thermal support to the gravitational equilibrium of the intracluster plasma.  Possible origins of the nonthermal component include CR protons, ongoing turbulence, and relativistic electrons; given the existing observational constraints on the first two options, we focus on the third.  For this to be effective, find that the e- population must include not only an energetic tail accelerated to gamma>1e3 responsible for the Coma radio halo, but also many more, lower energy electrons.  The e- acceleration is to be started by merging events similar to hose which provided the very high central entropy of the thermal intracluster plasma in Coma.

1212.3207
The evolution of galaxy sizes
Poggianti, et al

Galaxies with radii and masses comparable to high-z massive and compact galaxies represent 4.4% of all galaxies more massive that 3e10Msun in the field.  Such galaxies are 3x more frequent in clusters than in the field.  Most of them are early-type galaxies with intermediate to old stellar populations.  There is a trend of smaller radii for older luminosity-weighted ages at fixed galaxy mass.  Show the relation between size and luminosity-weighted age for galaxies of different stellar masses and in different environments.  Compare with high- z data to quantify the evolution of galaxy sizes.  Find that, once the progenitor bias due to the relation between galaxy size and stellar age is removed, the average amount of size evolution of individual galaxies between high- and low-z is mild, of the order of 1.6x.  

1212.3230
Quasi-periodical features in the distribution of luminous red galaxies
Ryabinkov, Kaurov, Kaminker

LRG statistical analysis from SDSS DR7 with 0.16<z<0.47 carried out.  Find that the radial distribution incorporates a few quasi-periodical components relative to eta, the dimensionless line-of-sight comoving distance calculated for the LCDM cosmological model.  101 h/Mpc period dominant and represent BAO, 135 h/Mpc period also exists, which differs for LRG samples of different characteristic (luminosity).  Caveat: show that estimations of the significance levels of the peaks strongly depend on a smoothed radial function as well as characteristics of random fluctuations.

1212.3273
Earth and Mars crater size frequence distribution and impact rates: theoretical and observational analysis
Bruckman, Ruiz, Ramos

1 megaton one every 3 years for Mars; 10 megaton one every century for Earth, according to the model.  Model allows the derivation of an expression that gives the number of craters observed today as a function of D (crater diameter) and age.  The application of this expression to the Earth's crater data shows a remarkable agreement between theory and observations.