scholarly journals Closure phase studies toward direct detection of light from hot Jupiters

2007 ◽  
Vol 3 (S249) ◽  
pp. 71-77
Author(s):  
Ming Zhao ◽  
John D. Monnier ◽  
Theo ten Brummelaar ◽  
Ettore Pedretti ◽  
Nathalie Thureau
Keyword(s):  
High Precision ◽  
Test Object ◽  
Direct Detection ◽  
Phase Measurements ◽  
Hot Jupiters ◽  
Long Baseline ◽  
Optical Interferometers ◽  
Phase Study ◽  
Chara Array ◽  
Very High

AbstractPrecision closure phase measurements obtained with ground-based long baseline optical interferometers is a promising way to directly detect light from nearby hot Jupiters. Here we present our closure phase simulations for the CHARA array for several bright hot Jupiters, υ And b, 51 Peg b, and τ Boo b. The maximum possible closure phase signals from these hot Jupiters are very small, for example, only ∼0.17 degrees for υ And b, requiring very high precision and stable closure phase measurements. We present preliminary results of a closure phase study on test object β Tau and hot Jupiter system υ And, both obtained with the MIRC instrument at the CHARA array. We demonstrate that directly detecting the light from hot Jupiters is feasible using high precision closure phase measurements obtained by CHARA-MIRC along with its sub-milli-arcsecond resolution, although challenges remain.

scholarly journals Toward Direct Detection of Hot Jupiters with Precision Closure Phase: Calibration Studies and First Results from the CHARA Array

2011 ◽  
Vol 123 (906) ◽  
pp. 964-975 ◽  
Author(s):  
M. Zhao ◽  
J. D. Monnier ◽  
X. Che ◽  
E. Pedretti ◽  
N. Thureau ◽  
...  
Keyword(s):  
Direct Detection ◽  
Hot Jupiters ◽  
First Results ◽  
Phase Calibration ◽  
Chara Array

Very high precision orbit of Capella by long baseline interferometry

1994 ◽  
Vol 107 ◽  
pp. 1859 ◽  
Author(s):  
C. A. Hummel ◽  
J. T. Armstrong ◽  
A. Quirrenbach ◽  
D. F. Buscher ◽  
D. Mozurkewich ◽  
...  
Keyword(s):  
High Precision ◽  
Long Baseline ◽  
Very High

scholarly journals Separate Universe calibration of the dependence of halo bias on cosmic web anisotropy

2020 ◽  
Vol 499 (3) ◽  
pp. 4418-4431 ◽  
Author(s):  
Sujatha Ramakrishnan ◽  
Aseem Paranjape
Keyword(s):  
Dark Matter ◽  
High Precision ◽  
Gaussian Distribution ◽  
Initial Perturbation ◽  
Analytical Framework ◽  
Web Environment ◽  
Wide Range ◽  
Galaxy Assembly ◽  
Very High ◽  
Good Agreement

ABSTRACT We use the Separate Universe technique to calibrate the dependence of linear and quadratic halo bias b1 and b2 on the local cosmic web environment of dark matter haloes. We do this by measuring the response of halo abundances at fixed mass and cosmic web tidal anisotropy α to an infinite wavelength initial perturbation. We augment our measurements with an analytical framework developed in earlier work that exploits the near-lognormal shape of the distribution of α and results in very high precision calibrations. We present convenient fitting functions for the dependence of b1 and b2 on α over a wide range of halo mass for redshifts 0 ≤ z ≤ 1. Our calibration of b2(α) is the first demonstration to date of the dependence of non-linear bias on the local web environment. Motivated by previous results that showed that α is the primary indicator of halo assembly bias for a number of halo properties beyond halo mass, we then extend our analytical framework to accommodate the dependence of b1 and b2 on any such secondary property that has, or can be monotonically transformed to have, a Gaussian distribution. We demonstrate this technique for the specific case of halo concentration, finding good agreement with previous results. Our calibrations will be useful for a variety of halo model analyses focusing on galaxy assembly bias, as well as analytical forecasts of the potential for using α as a segregating variable in multitracer analyses.

scholarly journals Equipartition principle for Wigner matrices

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhigang Bao ◽  
László Erdős ◽  
Kevin Schnelli
Keyword(s):  
High Precision ◽  
Quantum Systems ◽  
Wigner Matrices ◽  
Very High

Abstract We prove that the energy of any eigenvector of a sum of several independent large Wigner matrices is equally distributed among these matrices with very high precision. This shows a particularly strong microcanonical form of the equipartition principle for quantum systems whose components are modelled by Wigner matrices.

Formation flying for very high precision astrometry: NEAT and micro-NEAT mission concepts

2014 ◽  
Vol 2 (1) ◽  
pp. 3 ◽  
Author(s):  
Fabien Malbet ◽  
Alexis Brandeker ◽  
Alain Léger ◽  
Bjorn Jakobsson ◽  
Renaud Goullioud ◽  
...  
Keyword(s):  
High Precision ◽  
Formation Flying ◽  
Very High ◽  
Precision Astrometry

Gravitational waves: Some less discussed intriguing issues

2015 ◽  
Vol 24 (12) ◽  
pp. 1544023 ◽  
Author(s):  
C. Sivaram
Keyword(s):  
Gravitational Waves ◽  
Strong Field ◽  
Direct Detection ◽  
Recent Observation ◽  
High Redshift ◽  
Nonlinear Effects ◽  
Resonant Absorption ◽  
Compact Objects ◽  
The Waves ◽  
Very High

Attempts to detect gravitational waves is actively in progress with sophisticated devices like LIGO setup across continents. Despite being predicted almost 100 years ago, there has so far been no direct detection of these waves. In this work, we draw attention to some of the less discussed but subtle aspects arising, for example, from high orbital eccentricities, where emission near periastron could be millions of times more than that in the distant parts of the orbit. The strong field nonlinear effects close to the compact objects can substantially slow down and deflect the waves in the last (few) orbit(s) where much of the intensity is expected. Spin–orbit and other forces could be significant. There would also be plasma like resonant absorption (of kilohertz radiation) during the collapse. Recent observation of supermassive black holes at high redshift implies cluster collapse, where the gravitational wave intensity depends on very high powers of the mass. Any unambiguous claim of detection should perhaps consider several of these effects.

scholarly journals Performance of Multibeam Very High Throughput Satellite Systems Based on FSO Feeder Links with HPA Nonlinearity

2020 ◽  
Author(s):  
Emna Zedini ◽  
Abla Kammoun ◽  
Mohamed-Slim Alouini
Keyword(s):  
Outage Probability ◽  
High Throughput ◽  
Direct Detection ◽  
Satellite Communications ◽  
Ergodic Capacity ◽  
Heterodyne Detection ◽  
High Signal ◽  
Free Space Optical ◽  
Asymptotic Results ◽  
Very High

Due to recent advances in laser satellite communications technology, free-space optical (FSO) links are presented as an ideal alternative to the conventional radio frequency (RF) feeder links of the geostationary satellite for next generation very high throughput satellite (VHTS) systems. In this paper, we investigate the performance of multibeam VHTS systems that account for nonlinear high power amplifiers at the transparent fixed gain satellite transponder. Specifically, we consider the forward link of such systems, where the RF user link is assumed to follow the shadowed Rician model and the FSO feeder link is modeled by the Gamma-Gamma distribution in the presence of beam wander and pointing errors where it operates under either the intensity modulation with direct detection or the heterodyne detection. Moreover, zero-forcing precoder is employed to mitigate the effect of inter-beam interference caused by the aggressive frequency reuse in the user link. The performance of the system under study is evaluated in terms of the outage probability, the average bit-error rate (BER), and the ergodic capacity that are derived in exact closed-forms in terms of the bivariate Meijer's G function. Simple asymptotic results for the outage probability and the average BER are also obtained at high signal-to-noise ratio.

A HIGHLY ACCURATE BOOTSTRAPPING ALGORITHM FOR WORD SENSE DISAMBIGUATION

2001 ◽  
Vol 10 (01n02) ◽  
pp. 5-21 ◽  
Author(s):  
RADA F. MIHALCEA ◽  
DAN I. MOLDOVAN
Keyword(s):  
High Precision ◽  
Word Sense Disambiguation ◽  
Original Text ◽  
Word Sense ◽  
New Words ◽  
Input Text ◽  
Ambiguous Words ◽  
Sense Disambiguation ◽  
Very High

In this paper, we present a bootstrapping algorithm for Word Sense Disambiguation which succeeds in disambiguating a subset of the words in the input text with very high precision. It uses WordNet and a semantic tagged corpus, for the purpose of identifying the correct sense of the words in a given text. The bootstrapping process initializes a set of ambiguous words with all the nouns and verbs in the text. It then applies various disambiguation procedures and builds a set of disambiguated words: new words are sense tagged based on their relation to the already disambiguated words, and then added to the set. This process allows us to identify, in the original text, a set of words which can be disambiguated with high precision; 55% of the verbs and nouns are disambiguated with an accuracy of 92%.

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