` Jácome Armas `

my research focuses on describing black hole objects in higher dimensional gravity and string theory. in particular i work on effective descriptions of black holes as materials: wiggling them results in fluid motion while bending results in solid elastic behaviour. the interesting thing is that in the end ordinary black holes seem to be characterized by certain properties like viscosities, young modulus and piezoelectric moduli as a normal piece of wood (solid) or water flows (fluid). my aim is to be able to shine some light on particle physics through holographic dualities and to study the behaviour of quark and neutron stars.

you can find popular science reviews of my latest research here and here.

and here a complete list of my publications in theoretical physics.

relativistic elasticity of stationary fluid branes

this is a demonstration that any relativistic fluid in stationary motion confined to a surface behaves like a solid when the surface is deformed. infinitely extended black holes can be described as fluids confined to a surface and hence will behave like elastic solids. an elasticity theory for materials bent in time as well as in space is first developed.

black branes as piezoelectrics

when you bend a piece of wood there will be a higher concentration of matter in the inner region and a lower in the outer region. the same happens for black branes. in addition if the material is charged it will create an electric field and the material is said to be piezoelectric. this property is quantified here.

published in prl | article in arxiv.

thermal giant gravitons

giant gravitons are gravitons inflated into branes due to their uniform motion around a great circle of a spherical space. in this case we analyze the situation where it is moving on a anti-de sitter space times a sphere background. we consider giants at finite temperature but along the way a new zero temperature giant graviton is uncovered.

published in jhep | article in arxiv.

domain structure of space-times with a cosmological constant

black holes in higher dimensions are harder to characterize and their uniqueness difficult to evaluate. here it is provided a set of topologic and geometric invariants for black holes in (anti)-de sitter spacetimes. this is the first step for a uniqueness theorem in higher dimensions for non-trivial spacetimes.

published in prd | article in arxiv.

the young modulus of black strings and the fine structure of blackfolds

a connection between the physics of elastic materials and einstein's gravity is first made. black strings when bent can be seen as elastic solids which are characterized by a young modulus. this response coeffcient is first measured here for materials that are bent in time as well as in space.

published in jhep | article in arxiv.

blackfolds in (anti)-de sitter backgrounds

there are many black holes in higher dimensions but almost all of them are not analytically known. a systematic scan for new topologies in (anit)-de sitter spacetimes is initiated using the blackfold approach. odd-spheres, even-balls and helical rings are found. the kerr-(anti) de sitter black hole is shown to suffer from a gregory-laflamme instability.

published in prd | article in arxiv.

maximal analytic extension and hidden symmetries of the dipole black ring

what is the spacetime structure behind the horizon of a dipole black ring? pretty much the same as if it was a reissner-nordstrøm black hole. that is the main result found here but along the way the hidden symmetries of the charged ring are uncovered.

published in cqg | article in arxiv.

uniqueness theorem for black hole space-times with multiple disconnected horizons

already in five dimensions black holes can have many topologies and can have disconnected horizons like black saturns. a uniqueness theorem for black holes in minimal supergravity is proven given the rod structure and local charges as well as magnetic and chern-simmons fluxes.