Natural Neutrino Dark Energy

A new class of neutrino dark energy models is presented. The new models are characterized by the lack of exotic particles or couplings that violate the standard model symmetry. It is shown that these models lead to several concrete predictions for the dark energy equation of state, as well as possible effects on the cosmic structure formation. These predictions, can be verified (or disproved) with future experiments. At this point, the strongest constraints on these models are obtained from big bang nucleosynthesis, and lead to new bounds on the mass of the lightest neutrino.Comment: 14 pages, 6 figure

Unified Brane Gravity: Cosmological Dark Matter from Scale Dependent Newton Constant

We analyze, within the framework of unified brane gravity, the weak-field perturbations caused by the presence of matter on a 3-brane. Although deviating from the Randall-Sundrum approach, the masslessness of the graviton is still preserved. In particular, the four-dimensional Newton force law is recovered, but serendipitously, the corresponding Newton constant is shown to be necessarily lower than the one which governs FRW cosmology. This has the potential to puzzle out cosmological dark matter. A subsequent conjecture concerning galactic dark matter follows.Comment: 6 pages, to be published in Phys. Rev.

Hollowgraphy Driven Holography: Black Hole with Vanishing Volume Interior

Hawking-Bekenstein entropy formula seems to tell us that no quantum degrees of freedom can reside in the interior of a black hole. We suggest that this is a consequence of the fact that the volume of any interior sphere of finite surface area simply vanishes. Obviously, this is not the case in general relativity. However, we show that such a phenomenon does occur in various gravitational theories which admit a spontaneously induced general relativity. In such theories, due to a phase transition (one parameter family degenerates) which takes place precisely at the would have been horizon, the recovered exterior Schwarzschild solution connects, by means of a self-similar transition profile, with a novel 'hollow' interior exhibiting a vanishing spatial volume and a locally varying Newton constant. This constitutes the so-called 'hollowgraphy' driven holography.Comment: Honorable Mention Essay - Gravity Research Foundation (2010

Fermi-bubble bulk and edge analysis reveals dust, cooling breaks, and cosmic-ray diffusion, facilitating a self-consistent model

The full, radio to $\gamma$-ray spectrum of the Fermi bubbles is shown to be consistent with standard strong-shock electron acceleration at the bubble edge, without ad-hoc energy cutoffs, if the ambient interstellar radiation is strong; the $\gamma$-ray cooling break should then have a microwave counterpart, undetected until now. Indeed, a broadband bubble-edge analysis uncovers a pronounced downstream dust component, which masked the anticipated $\sim35$ GHz spectral break, and the same overall radio softening consistent with Kraichnan diffusion previously reported in $\gamma$-rays.Comment: 6 pages, 3 figures, SI; comments welcom

Holographic Entropy Packing inside a Black Hole

If general relativity is spontaneously induced, the black hole limit is governed by a phase transition which occurs precisely at the would have been horizon. The exterior Schwarzschild solution then connects with a novel core of vanishing spatial volume. The Kruskal structure, admitting the exact Hawking imaginary time periodicity, is recovered, with the conic defect defused at the origin, rather than at the horizon. The entropy stored inside \textbf{any} interior sphere is universal, equal to a quarter of its surface area, thus locally saturating the 't Hooft-Susskind holographic bound. The associated Komar mass and material energy functions are non-singular.Comment: [V3] accepted to PRL (version shortened, a paragraph on singularity structure added); 10 pages, no figure