189 research outputs found
The Spin-Orbit Evolution of GJ 667C System: The Effect of Composition and Other Planet's Perturbations
Potentially habitable planets within the habitable zone of M-dwarfs are
affected by tidal interaction. We studied the tidal evolution in GJ 667C using
a numerical code we call TIDEV. We reviewed the problem of the dynamical
evolution focusing on the effects that a rheological treatment, different
compositions and the inclusion of orbital perturbations, have on the spin-down
time and the probability to be trapped in a low spin-orbit resonance.
Composition have a strong effect on the spin-down time, changing, in some
cases, by almost a factor of 2 with respect to the value estimated for a
reference Earth-like model. We calculated the time to reach a low resonance
value (3:2) for the configuration of 6 planets. Capture probabilities are
affected when assuming different compositions and eccentricities variations. We
chose planets b and c to evaluate the probabilities of capture in resonances
below 5:2 for two compositions: Earth-like and Waterworld planets. We found
that perturbations, although having a secular effect on eccentricities, have a
low impact on capture probabilities and noth- ing on spin-down times. The
implications of the eccentricity variations and actual habitability of the GJ
667C system are discussed.Comment: 15 pages, 9 figures, 4 tables. Accepted for publication in MNRAS - V
Ultrafast control of Rabi oscillations in a polariton condensate
We report the experimental observation and control of space and time-resolved
light-matter Rabi oscillations in a microcavity. Our setup precision and the
system coherence are so high that coherent control can be implemented with
amplification or switching off of the oscillations and even erasing of the
polariton density by optical pulses. The data is reproduced by a fundamental
quantum optical model with excellent accuracy, providing new insights on the
key components that rule the polariton dynamics.Comment: 5 pages, 3 figures, supplementary 7 pages, 4 figures. Supplementary
videos:
https://drive.google.com/folderview?id=0B0QCllnLqdyBNjlMLTdjZlNhbTQ&usp=sharin
Mass and pressure constraints on galaxy clusters from interferometric SZ observations
Following on our previous study of an analytic parametric model to describe
the baryonic and dark matter distributions in clusters of galaxies with
spherical symmetry, we perform an SZ analysis of a set of simulated clusters
and present their mass and pressure profiles. The simulated clusters span a
wide range in mass, 2.0 x 10^14 Msun < M200 < 1.0 x 10^15Msun, and observations
with the Arcminute Microkelvin Imager (AMI) are simulated through their
Sunyaev- Zel'dovich (SZ) effect. We assume that the dark matter density follows
a Navarro, Frenk and White (NFW) profile and that the gas pressure is described
by a generalised NFW (GNFW) profile. By numerically exploring the probability
distributions of the cluster parameters given simulated interferometric SZ data
in the context of Bayesian methods, we investigate the capability of this model
and analysis technique to return the simulated clusters input quantities. We
show that considering the mass and redshift dependency of the cluster halo
concentration parameter is crucial in obtaining an unbiased cluster mass
estimate and hence deriving the radial profiles of the enclosed total mass and
the gas pressure out to r200.Comment: 5 pages, 2 tables, 3 figure
The Evolution of K* and the Halo Occupation Distribution since z=1.5: Observations vs. Simulations
We study the evolution of the K-band luminosity function (LF) and the Halo
Occupation Distribution (HOD) using Subaru observations of 15 X-ray clusters at
z=0.8-1.5 and compare the results with mock clusters (0<z<1.3) extracted from
the Millennium Simulation and populated with galaxies using the semi-analytic
model (SAM) of Bower et al., matched in mass to our observed sample. We find
that the characteristic luminosity K* defined by a Shechter LF is consistent
with SAM predictions, which mimic well the evolution of K* in z>1 rich
clusters. However, we cannot distinguish between this model and a simple
stellar population synthesis model invoking passive evolution with a formation
redshift z~5 - consistent with the presence of an old red galaxy population
ubiquitous in rich clusters at z=1.5. We also see a small difference (\Delta
K*~0.5) between our clusters and studies of the field population at similar
redshifts, suggesting only a weak dependence of the luminous (L>L*) part of the
LF on environment. Turning to our HOD study, we find that within R_{500},
high-z clusters tend to host smaller numbers of galaxies to a magnitude K*+2
compared to their low-z counterparts. This behavior is also seen in the mock
samples and is relatively insensitive to the average mass of the cluster
haloes. In particular, we find significant correlations of the observed number
of member cluster galaxies (N) with both z and cluster mass:
.
Finally, we examine the spatial distribution of galaxies and provide a new
estimate of the concentration parameter for clusters at high z
(). Our result is consistent with predictions from
both our SAM mock clusters and literature's predictions for dark matter haloes.
The mock sample predictions rise slowly with decreasing redshift reaching
at z=0.Comment: 17 pages, 3 tables, 12 Figures. Accepted for publications in MNRAS.
Version 2: modified Figs. 4, 8 and 1
Quantum correlations between two distant cavity QED systems coupled by a mechanical resonator
Achieving quantum correlations between two distant systems is a desirable
feature for quantum networking. In this work, we study a system composed of two
quantum emitter-cavity subsystems spatially separated. A mechanical resonator
couples to either both quantum emitters or both cavities leading to quantum
correlations between both subsystems such as non-local light-matter dressed
states and cavity-cavity normal mode splitting. These indirect couplings can be
explained by an effective Hamiltonian for large energy detuning between the
mechanical resonator and the atoms/cavities. Moreover, it is found optimal
conditions for the physical parameters of the system in order to maximize the
entanglement of such phonon-mediated couplings
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