Friday, September 24, 2010

Structure Formation with Decaying Neutrinos

Structure Formation with Decaying Neutrinos

White, Gelmini, & Silk (1994)

http://arxiv.org/abs/astro-ph/9411098




This CDM model has been ruled out by WMAP but is still interesting from an educational perspective.

Gauge

Solar and Atmospheric Neutrinos: Limitations for Direct Dark Matter Searches

From Solar and Atmospheric Neutrinos: Limitations for Direct Dark Matter Searches, by Gütlein et al.

Solar and atmospheric neutrinos limit our ability to detect dark matter

Friday, September 17, 2010

An equivalence principle for scalar forces

[arxiv:1009.2520] "An equivalence principle for scalar forces" by Lam Hui and Alberto Nicolis.
 The authors try to find some sort of equivalence principle for the interaction between scalar fields and other fields given stress-energy conservation alone. They suggest a coupling \[phi T_m\] I don't think they've found a real general result but it is an interesting question.


Also, in the spirit of last week:
Robust limit on a varying proton-to-electron mass ratio from a single H2 system by Wendt and Molaro link

Coherent Combination of BAO and Peculiar Velocity Measurements from Redshift Survey: arXiv:1009.2753

Same as the paper Jun-Z brought to the Journal Club this morning.
I'll briefly explain why this boring looking contours are actually interesting.

Friday, September 10, 2010

Evidence for spatial variation of the fine structure constant

I think this is probably non-sense... but it's perhaps interesting if true.
http://arxiv.org/abs/1008.3907

Existence of collisional trajectories of Mercury, Mars and Venus with the Earth

Nature 459, 817-819 (11 June 2009)
Existence of collisional trajectories of Mercury, Mars and Venus with the Earth
J. Laskar & M. Gastineau

Amazing sensitivity to initial conditions!


Evolution of the maximum eccentricity of Mercury (computed over 1-Myr intervals) over 5 Gyr. a, Pure Newtonian model without the contribution of the Moon, for 201 solutions with initial conditions that differ by only 3.8 cm in the semi-major axis of Mercury. b, Full Solar System model with relativistic and lunar contributions, for 2,501 solutions with initial conditions that differ by only 0.38 mm in the semi-major axis of Mercury.

Friday, September 3, 2010

The Matter Power Spectrum Suppressed by Warm Dark Matter

The clustering properties of the first galaxies

The clustering properties of the first galaxies

Stiavelli & Trenti, http://arxiv.org/abs/0911.3368

These authors suggest the idea that the very first galaxies that are most highly clustered may not be not be as primordial in chemical composition as naively expected. This is because the high clustering implies rapid enrichment. Metal-free galaxies may therefore best be searched for in less-custered underdense regions. Hence, primordial galaxies may be second (in terms of chronological order).