Quantum Interference to Measure Spacetime Curvature: A Proposed Experiment at the Intersection of Quantum Mechanics and General Relativity

An experiment in Low Earth Orbit (LEO) is proposed to measure components of the Riemann curvature tensor using atom interferometry. We show that the difference in the quantum phase $\Delta\phi$ of an atom that can travel along two intersecting geodesics is given by $mR_{0i0j}/\hbar$ times the spacetime volume contained within the geodesics. Our expression for $\Delta\phi$ also holds for gravitational waves in the long wavelength limit.Comment: 7 pages LaTeXed with RevTeX 4.0, 2 figures. Submitted to the 2003 Gravity Research Foundation Essay Contes

A Shell of Thermal X-ray Emission Associated with the Young Crab-like Remnant 3C58

Deep X-ray imaging spectroscopy of the bright pulsar wind nebula 3C58 confirms the existence of an embedded thermal X-ray shell surrounding the pulsar PSR J0205+6449. Radially resolved spectra obtained with the XMM-Newton telescope are well-characterized by a power-law model with the addition of a soft thermal emission component in varying proportions. These fits reproduce the well-studied increase in the spectral index with radius attributed to synchrotron burn-off of high energy electrons. Most interestingly, a radially resolved thermal component is shown to map out a shell-like structure ~6' in diameter. The presence of a strong emission line corresponding to the Ne IX He-like transition requires an overabundance of ~3 x [Ne/Ne(sun)] in the Raymond-Smith plasma model. The best-fit temperature kT ~ 0.23 keV is essentially independent of radius for the derived column density of N_H = (4.2 +/- 0.1)E21 per cm squared. Our result suggests that thermal shells can be obscured in the early evolution of a supernova remnant by non-thermal pulsar wind nebulae emission; the luminosity of the 3C58 shell is more than an order of magnitude below the upper limit on a similar shell in the Crab Nebula. We find the shell centroid to be offset from the pulsar location. If this neutron star has a velocity similar to that of the Crab pulsar, we derive an age of 3700 yr and a velocity vector aligned with the long axis of the PWN. The shell parameters and pulsar offset add to the accumulating evidence that 3C58 is not the remnant of the supernova of CE 1181.Comment: 7 pages, 8 figures, 2 tables, Latex emulateapj style. To appear in the Astrophysical Journa

Observation of an energetic radiation burst from mountain-top thunderclouds

During thunderstorms on 2008 September 20, a simultaneous detection of gamma rays and electrons was made at a mountain observatory in Japan located 2770 m above sea level. Both emissions, lasting 90 seconds, were associated with thunderclouds rather than lightning. The photon spectrum, extending to 10 MeV, can be interpreted as consisting of bremsstrahlung gamma rays arriving from a source which is 60 - 130 m in distance at 90% confidence level. The observed electrons are likely to be dominated by a primary population escaping from an acceleration region in the clouds.Comment: 12 pages, 3 figures, accepted for publication in Physical Review Letter

Abelian Higgs Hair for AdS-Schwarzschild Black Hole

We show that the Abelian Higgs field equations in the background of the four dimensional AdS-Schwarzschild black hole have a vortex line solution. This solution, which has axial symmetry, is a generalization of the AdS spacetime Nielsen-Olesen string. By a numerical study of the field equations, we show that black hole could support the Abelian Higgs field as its Abelian hair. Also, we conside the self gravity of the Abelian Higgs field both in the pure AdS spacetime and AdS-Schwarzschild black hole background and show that the effect of string as a black hole hair is to induce a deficit angle in the AdS-Schwarzschild black hole.Comment: 19 pages, 33 figure

Thermal-Fluid Flow Transport Phenomenon over Slot-Perforated Flat Plates Placed in Narrow Channel

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76151/1/AIAA-25872-119.pd

Do naked singularities generically occur in generalized theories of gravity?

A new mechanism for causing naked singularities is found in an effective superstring theory. We investigate the gravitational collapse in a spherically symmetric Einstein-Maxwell-dilaton system in the presence of a pure cosmological constant "potential", where the system has no static black hole solution. We show that once gravitational collapse occurs in the system, naked singularities necessarily appear in the sense that the field equations break down in the domain of outer communications. This suggests that in generalized theories of gravity, the non-minimally coupled fields generically cause naked singularities in the process of gravitational collapse if the system has no static or stationary black hole solution.Comment: 4 pages including 2 eps figures, to be published in Physical Review Letter

Perturbations of global monopoles as a black hole's hair

We study the stability of a spherically symmetric black hole with a global monopole hair. Asymptotically the spacetime is flat but has a deficit solid angle which depends on the vacuum expectation value of the scalar field. When the vacuum expectation value is larger than a certain critical value, this spacetime has a cosmological event horizon. We investigate the stability of these solutions against the spherical and polar perturbations and confirm that the global monopole hair is stable in both cases. Although we consider some particular modes in the polar case, our analysis suggests the conservation of the "topological charge" in the presence of the event horizons and violation of black hole no-hair conjecture in asymptotically non-flat spacetime.Comment: 11 pages, 2 figures, some descriptions were improve

HESS J1616-508: likely powered by PSR J1617-5055

HESS J1616-508 is one of the brightest emitters in the TeV sky. Recent observations with the IBIS/ISGRI telescope on board the INTEGRAL spacecraft have revealed that a young, nearby and energetic pulsar, PSR J1617-5055, is a powerful emitter of soft gamma-rays in the 20-100 keV domain. In this paper we present an analysis of all available data from the INTEGRAL, Swift, BeppoSAX and XMM-Newton telescopes with a view to assessing the most likely counterpart to the HESS source. We find that the energy source that fuels the X/gamma-ray emissions is derived from the pulsar, both on the basis of the positional morphology, the timing evidence and the energetics of the system. Likewise, the 1.2% of the pulsar's spin down energy loss needed to power the 0.1-10 TeV emission is also fully consistent with other HESS sources known to be associated with pulsars. The relative sizes of the X/gamma-ray and VHE sources are consistent with the expected lifetimes against synchrotron and Compton losses for a single source of parent electrons emitted from the pulsar. We find that no other known object in the vicinity could be reasonably considered as a plausible counterpart to the HESS source. We conclude that there is good evidence to assume that the HESS J1616-508 source is driven by PSR J1617-5055 in which a combination of synchrotron and inverse Compton processes combine to create the observed morphology of a broad-band emitter from keV to TeV energies.Comment: 7 pages, including 5 figures and 1 table. Accepted for publication in MNRA

Spacetime structure of static solutions in Gauss-Bonnet gravity: neutral case

We study the spacetime structures of the static solutions in the $n$-dimensional Einstein-Gauss-Bonnet-$\Lambda$ system systematically. We assume the Gauss-Bonnet coefficient $\alpha$ is non-negative. The solutions have the $(n-2)$-dimensional Euclidean sub-manifold, which is the Einstein manifold with the curvature $k=1,~0$ and -1. We also assume $4{\tilde \alpha}/\ell^2\leq 1$, where $\ell$ is the curvature radius, in order for the sourceless solution (M=0) to be defined. The general solutions are classified into plus and minus branches. The structures of the center, horizons, infinity and the singular point depend on the parameters $\alpha$, $\ell^2$, $k$, $M$ and branches complicatedly so that a variety of global structures for the solutions are found. In the plus branch, all the solutions have the same asymptotic structure at infinity as that in general relativity with a negative cosmological constant. For the negative mass parameter, a new type of singularity called the branch singularity appears at non-zero finite radius $r=r_b>0$. The divergent behavior around the singularity in Gauss-Bonnet gravity is milder than that around the central singularity in general relativity. In the $k=1,~0$ cases the plus-branch solutions do not have any horizon. In the $k=-1$ case, the radius of the horizon is restricted as $r_h\sqrt{2\tilde{\alpha}}$) in the plus (minus) branch. There is also the extreme black hole solution with positive mass in spite of the lack of electromagnetic charge. We briefly discuss the effect of the Gauss-Bonnet corrections on black hole formation in a collider and the possibility of the violation of third law of the black hole thermodynamics.Comment: 19 pages, 11 figure