282 research outputs found
The holographic supersymmetric Renyi entropy in five dimensions
We compute the supersymmetric Renyi entropy across an entangling three-sphere
for five-dimensional superconformal field theories using localization. For a
class of USp(2N) gauge theories we construct a holographic dual 1/2 BPS black
hole solution of Euclidean Romans F(4) supergravity. The large N limit of the
gauge theory results agree perfectly with the supergravity computations.Comment: 19 page
Localization on Three-Manifolds
We consider supersymmetric gauge theories on Riemannian three-manifolds with
the topology of a three-sphere. The three-manifold is always equipped with an
almost contact structure and an associated Reeb vector field. We show that the
partition function depends only on this vector field, giving an explicit
expression in terms of the double sine function. In the large N limit our
formula agrees with a recently discovered two-parameter family of dual
supergravity solutions. We also explain how our results may be applied to prove
vortex-antivortex factorization. Finally, we comment on the extension of our
results to three-manifolds with non-trivial fundamental group.Comment: 34 pages; v2: discussion of vortex factorization added; v3: minor
correction
A New Infinite Class of Sasaki-Einstein Manifolds
We show that for every positive curvature Kahler-Einstein manifold in
dimension 2n there is a countably infinite class of associated Sasaki-Einstein
manifolds X_{2n+3} in dimension 2n+3. When n=1 we recover a recently discovered
family of supersymmetric AdS_5 x X_5 solutions of type IIB string theory, while
when n=2 we obtain new supersymmetric AdS_4 x X_7 solutions of D=11
supergravity. Both are expected to provide new supergravity duals of
superconformal field theories.Comment: 12 pages. v2: minor typos corrected, comment on generalisation to
product base manifold
Supersymmetric solutions to Euclidean Romans supergravity
We study Euclidean Romans supergravity in six dimensions with a non-trivial
Abelian R-symmetry gauge field. We show that supersymmetric solutions are in
one-to-one correspondence with solutions to a set of differential constraints
on an SU(2) structure. As an application of our results we (i) show that this
structure reduces at a conformal boundary to the five-dimensional rigid
supersymmetric geometry previously studied by the authors, (ii) find a general
expression for the holographic dual of the VEV of a BPS Wilson loop, matching
an exact field theory computation, (iii) construct holographic duals to
squashed Sasaki-Einstein backgrounds, again matching to a field theory
computation, and (iv) find new analytic solutions.Comment: 31 pages; v2: published version (with reference added
Supersymmetric gauge theories on squashed five-spheres and their gravity duals
We construct the gravity duals of large N supersymmetric gauge theories
defined on squashed five-spheres with SU(3) x U(1) symmetry. These five-sphere
backgrounds are continuously connected to the round sphere, and we find a
one-parameter family of 3/4 BPS deformations and a two-parameter family of
(generically) 1/4 BPS deformations. The gravity duals are constructed in
Euclidean Romans F(4) gauged supergravity in six dimensions, and uplift to
massive type IIA supergravity. We holographically renormalize the Romans
theory, and use our general result to compute the renormalized on-shell actions
for the solutions. The results agree perfectly with the large N limit of the
dual gauge theory partition function, which we compute using large N matrix
model techniques. In addition we compute BPS Wilson loops in these backgrounds,
both in supergravity and in the large N matrix model, again finding precise
agreement. Finally, we conjecture a general formula for the partition function
on any five-sphere background, which for fixed gauge theory depends only on a
certain supersymmetric Killing vector.Comment: 63 pages, no figures; v2: minor corrections and reference adde
Supersymmetric gauge theories on five-manifolds
We construct rigid supersymmetric gauge theories on Riemannian
five-manifolds. We follow a holographic approach, realizing the manifold as the
conformal boundary of a six-dimensional bulk supergravity solution. This leads
to a systematic classification of five-dimensional supersymmetric backgrounds
with gravity duals. We show that the background metric is furnished with a
conformal Killing vector, which generates a transversely holomorphic foliation
with a transverse Hermitian structure. Moreover, we prove that any such metric
defines a supersymmetric background. Finally, we construct supersymmetric
Lagrangians for gauge theories coupled to arbitrary matter on such backgrounds.Comment: 35 pages: v2: minor corrections and references added. Published
versio
The large N limit of M2-branes on Lens spaces
We study the matrix model for N M2-branes wrapping a Lens space L(p,1) =
S^3/Z_p. This arises from localization of the partition function of the ABJM
theory, and has some novel features compared with the case of a three-sphere,
including a sum over flat connections and a potential that depends
non-trivially on p. We study the matrix model both numerically and analytically
in the large N limit, finding that a certain family of p flat connections give
an equal dominant contribution. At large N we find the same eigenvalue
distribution for all p, and show that the free energy is simply 1/p times the
free energy on a three-sphere, in agreement with gravity dual expectations.Comment: 28 pages, 4 figure
The Mid-Infrared Emission of M87
We discuss Subaru and Spitzer Space Telescope imaging and spectroscopy of M87
in the mid-infrared from 5-35 um. These observations allow us to investigate
mid-IR emission mechanisms in the core of M87 and to establish that the
flaring, variable jet component HST-1 is not a major contributor to the mid-IR
flux. The Spitzer data include a high signal-to-noise 15-35 m spectrum of
the knot A/B complex in the jet, which is consistent with synchrotron emission.
However, a synchrotron model cannot account for the observed {\it nuclear}
spectrum, even when contributions from the jet, necessary due to the degrading
of resolution with wavelength, are included. The Spitzer data show a clear
excess in the spectrum of the nucleus at wavelengths longer than 25 um, which
we model as thermal emission from cool dust at a characteristic temperature of
55 \pm 10 K, with an IR luminosity \sim 10^{39} {\rm ~erg ~s^{-1}}. Given
Spitzer's few-arcsecond angular resolution, the dust seen in the nuclear
spectrum could be located anywhere within ~5'' (390 pc) of the nucleus. In any
case, the ratio of AGN thermal to bolometric luminosity indicates that M87 does
not contain the IR-bright torus that classical unified AGN schemes invoke.
However, this result is consistent with theoretical predictions for
low-luminosity AGNsComment: 9 pages, 7 figures, ApJ, in pres
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Evaluating the structure and magnitude of the ash plume during the initial phase of the 2010 Eyjafjallajökull eruption using lidar observations and NAME simulations
The Eyjafjallajökull volcano in Iceland erupted explosively on 14 April 2010, emitting a plume of ash into the atmosphere. The ash was transported from Iceland toward Europe where mostly cloud-free skies allowed ground-based lidars at Chilbolton in England and Leipzig in Germany to estimate the mass concentration in the ash cloud as it passed overhead. The UK Met Office's Numerical Atmospheric-dispersion Modeling Environment (NAME) has been used to simulate the evolution of the ash cloud from the Eyjafjallajökull volcano during the initial phase of the ash emissions, 14–16 April 2010. NAME captures the timing and sloped structure of the ash layer observed over Leipzig, close to the central axis of the ash cloud. Relatively small errors in the ash cloud position, probably caused by the cumulative effect of errors in the driving meteorology en route, result in a timing error at distances far from the central axis of the ash cloud. Taking the timing error into account, NAME is able to capture the sloped ash layer over the UK. Comparison of the lidar observations and NAME simulations has allowed an estimation of the plume height time series to be made. It is necessary to include in the model input the large variations in plume height in order to accurately predict the ash cloud structure at long range. Quantitative comparison with the mass concentrations at Leipzig and Chilbolton suggest that around 3% of the total emitted mass is transported as far as these sites by small (<100 μm diameter) ash particles
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