Centrally extended symmetry algebra of asymptotically Goedel spacetimes

We define an asymptotic symmetry algebra for three-dimensional Goedel spacetimes supported by a gauge field which turns out to be the semi-direct sum of the diffeomorphisms on the circle with two loop algebras. A class of fields admitting this asymptotic symmetry algebra and leading to well-defined conserved charges is found. The covariant Poisson bracket of the conserved charges is then shown to be centrally extended to the semi-direct sum of a Virasoro algebra and two affine algebras.Comment: 12 pages, sign mistake corrected in the central charge, takes precedence over published versio

Solar-powered Water Purification and Community Development in Haiti\u27s Artibonite Valley

In May 2017, the Project Haiti team of two faculty and eleven students from Embry-Riddle Aeronautical University, Daytona Beach, Florida, working together with a professor and translator from the Universite d’Etat d’Haiti, designed and installed a solar-powered water purification system in the village of Drouin, Artibonite Department, Haiti. This region has been at the epicenter of the post-2010 cholera epidemic that has infected hundreds of thousands and killed many thousands. There has been no reliably safe drinking water in the region. The Haitian operators were empowered with ongoing maintenance and operation of the system, as well as the micro-business operations. Partnership with Haitians and the long-term partnering NGO (non-governmental organization) is a critical enabling aspect that improves sustainability of this community development effort

Microscopics of Extremal Kerr from Spinning M5 Branes

We show that the spinning magnetic one-brane in minimal five-dimensional supergravity admits a decoupling limit that interpolates smoothly between a self-dual null orbifold of AdS_3 \times S^2 and the near-horizon limit of the extremal Kerr black hole times a circle. We use this interpolating solution to understand the field theory dual to spinning M5 branes as a deformation of the Discrete Light Cone Quantized (DLCQ) Maldacena-Stominger-Witten (MSW) CFT. In particular, the conformal weights of the operators dual to the deformation around AdS_3 \times S^2 are calculated. We present pieces of evidence showing that a CFT dual to the four-dimensional extremal Kerr can be obtained from the deformed MSW CFT.Comment: 5 page

Central Charges in Extreme Black Hole/CFT Correspondence

The Kerr/CFT correspondence has been recently broadened to the general extremal black holes under the assumption that the central charges from the non-gravitational fields vanish. To confirm this proposal, we derive the expression of the conserved charges in the Einstein-Maxwell-scalar theory with topological terms in four and five dimensions and check that the above assumption was correct. Combining the computed central charge with the expected form of the temperature, the Bekenstein-Hawking entropy of the general extremal black holes in four and five dimensions can be reproduced by using the Cardy formula.Comment: 20 pages, v2:references added, published in JHE

A General Black String and its Microscopics

Using G2(2) dualities we construct the most general black string solution of minimal five-dimensional ungauged supergravity. The black string has five independent parameters, namely, the magnetic one-brane charge, smeared electric zero-brane charge, boost along the string direction, energy above the BPS bound, and rotation in the transverse space. In one extremal limit it reduces to the three parameter supersymmetric string of five-dimensional minimal supergravity; in another extremal limit it reduces to the three parameter non-supersymmetric extremal string of five-dimensional minimal supergravity. It also admits an extremal limit when it has maximal rotation in the four-dimensional transverse space. The decoupling limit of our general black string is a BTZ black hole times a two sphere. The macroscopic entropy of the string is reproduced by the Maldacena-Strominger-Witten CFT in appropriate ranges of the parameters. When the pressureless condition is imposed, our string describes the infinite radius limit of the most general class of black rings of minimal supergravity. We discuss implications our solution has for extremal and non-extremal black rings of minimal supergravity.Comment: 35 pages; 3 figures; v2 section 4.1.1 rewritten + minor changes + ref adde

The relativistic fluid dual to vacuum Einstein gravity

We present a construction of a (d+2)-dimensional Ricci-flat metric corresponding to a (d+1)-dimensional relativistic fluid, representing holographically the hydrodynamic regime of a (putative) dual theory. We show how to obtain the metric to arbitrarily high order using a relativistic gradient expansion, and explicitly carry out the computation to second order. The fluid has zero energy density in equilibrium, which implies incompressibility at first order in gradients, and its stress tensor (both at and away from equilibrium) satisfies a quadratic constraint, which determines its energy density away from equilibrium. The entire dynamics to second order is encoded in one first order and six second order transport coefficients, which we compute. We classify entropy currents with non-negative divergence at second order in relativistic gradients. We then verify that the entropy current obtained by pulling back to the fluid surface the area form at the null horizon indeed has a non-negative divergence. We show that there are distinct near-horizon scaling limits that are equivalent either to the relativistic gradient expansion we discuss here, or to the non-relativistic expansion associated with the Navier-Stokes equations discussed in previous works. The latter expansion may be recovered from the present relativistic expansion upon taking a specific non-relativistic limit.Comment: 29 pages, 1 figure; v2: added comments and references, published versio

A Microcosm of Sustainable Practices: Honors Program and Project Haiti Partnership with Derbyshire Community Garden

The Embry-Riddle Honors Program has been partnering with and growing the Derbyshire Community Garden consistently/perpetually for the past two years, playing an increasingly managerial role. We emphasize regenerative practices, from planting a wide variety of heirloom organic seeds; to vermicomposting; to fully avoiding any chemical fertilizers, herbicides, and pesticides; to operating a Saturday produce market on site, supporting local residents in this food-insecure neighborhood with fresh, organic, nutrient-rich foods. Partnering with ERAU’s Project Haiti, the Haiti team has diverted some of its Ford Campus Community Challenge grant award (due to the team’s inability to travel to Haiti, chiefly due to social/political instability) to install an 18 panel ground-mounted solar array inside the Garden space, providing all of the power needed for Garden operation…plus reducing the electrical grid reliance of the adjoining Derbyshire Community Center by an estimated 25% monthly. We are moving closer to “closed loop system,” overall. This involvement and partnership highlights the following: Localized, high-caliber, individualized food production versus full reliance on long, complex (and vulnerable) supply chains Regenerative, organic agricultural practices versus “Green Revolution” industrialized, chemical-intensive agriculture Biodiversity and seed-saving/sharing versus the narrowing range of seed made available via large-scale, industrial agriculture/monoculture Attention to building healthy soil as a key to overall health, versus the extractive practices commonly in place Clean, sustainable sources of energy and the link between solar and agriculture (agrivoltaics) Re/invigorating community connections across generational, gender, racial, national, and economic “boundaries” Combined, these now-established features at Derbyshire open many further opportunities for on-site education regarding localized management and control, environmental stewardship, community impact and engagement, and environmental and human health