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In this paper, we study the degeneracies among several cosmological parameters in detail and discuss their impacts on the determinations of these parameters from the current and future observations. By combining the latest data sets,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Hong Li , Jun-Qing Xia

The increasing number of spectra gathered by spectroscopic sky surveys and transiting exoplanet follow-up has pushed the community to develop automated tools for atmospheric stellar parameters determination. Here we present a novel approach…

Solar and Stellar Astrophysics · Physics 2017-06-28 Luca Malavolta , Christophe Lovis , Francesco Pepe , Christopher Sneden , Stephane Udry

Context: L-type ultra-cool dwarfs and brown dwarfs have cloudy atmospheres that could host weather-like phenomena. The detection of photometric or spectral variability would provide insight into unresolved atmospheric heterogeneities, such…

We study the consistency of the physical properties of galaxies retrieved from SED-fitting as a function of spectral resolution and signal-to-noise ratio (SNR). Using a selection of physically motivated star formation histories, we set up a…

About 70-80% of stars in our solar and galactic neighborhood are M dwarfs. They span a range of low masses and temperatures relative to solar-type stars, facilitating molecule formation throughout their atmospheres. Standard stellar…

Solar and Stellar Astrophysics · Physics 2023-02-22 Aishwarya R. Iyer , Michael R. Line , Philip S. Muirhead , Jonathan J. Fortney , Ehsan Gharib-Nezhad

Various strategies for extracting or constraining the weak phase gamma with controlled theoretical uncertainties are reviewed. Measurements of the rates for the hadronic decays B^+- -> pi K provide largely model-independent information on…

High Energy Physics - Phenomenology · Physics 2007-05-23 Matthias Neubert

The mid-infrared spectrum contains rich diagnostics to probe the physical properties of galaxies, among which the pervasive emission features from polycyclic aromatic hydrocarbons (PAHs) offer a promising means of estimating the star…

Astrophysics of Galaxies · Physics 2020-12-23 Lulu Zhang , Luis C. Ho , Yanxia Xie

The Sandage-Loeb (SL) test directly measures the expansion rate of the universe in the redshift range of $2\lesssim z\lesssim 5$ by detecting redshift drift in the spectra of Lyman-$\alpha$ forest of distant quasars. We discuss the impact…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-11 Jia-Jia Geng , Jing-Fei Zhang , Xin Zhang

We study degeneracies between cosmological parameters and measurement errors from cosmic shear surveys using a principal component analysis of the Fisher matrix. We simulate realistic survey topologies with non-uniform sky coverage, and…

Astrophysics · Physics 2009-11-13 Dipak Munshi , Martin Kilbinger

Very metal-poor (VMP, [Fe/H]<-2.0) stars offer a wealth of information on the nature and evolution of elemental production in the early galaxy and universe. The upcoming China Space Station Telescope (CSST) will provide us with a large…

Solar and Stellar Astrophysics · Physics 2023-02-23 Tianmin Wu , Yude Bu , Jianhang Xie , Junchao Liang , Wei Liu , Zhenping Yi , Xiaoming Kong , Meng Liu

We have obtained infrared (1 to 2.5 micron) spectroscopy for 42 halo and disk dwarfs with spectral type M1 to M6.5. These data are compared to synthetic spectra generated by the latest model atmospheres of Allard & Hauschildt. Photospheric…

Astrophysics · Physics 2009-05-29 S. K. Leggett , F. Allard , Conard Dahn , P. H. Hauschildt , T. H. Kerr , J. Rayner

We present the first models allowing one to explore in a consistent way the influence of changes in the alpha-element-to-iron abundance ratio on the high-resolution spectral properties of evolving stellar populations. The models cover the…

Astrophysics · Physics 2008-01-08 P. Coelho , G. Bruzual , S. Charlot , A. Weiss , B. Barbuy , J. Ferguson

We present an analysis of mock X-ray spectra and light curves of magnetic cataclysmic variables using an upgraded version of the 3D CYCLOPS code. This 3D representation of the accretion flow allows us to properly model total and partial…

We report an independent spectral classification of a sample of poorly studied M-dwarf candidate stars observed with the OSIRIS instrument at GTC. Our project was carried out as an independent test of the spectral classification. It is…

Solar and Stellar Astrophysics · Physics 2019-12-24 Cristina Cabello , Géza Csörnyei , Jaroslav Merc , Verónica Ferreirós Lopez , Peter Pessev

We present a unified framework to derive fundamental stellar parameters by combining all available observational and theoretical information for a star. The algorithm relies on the method of Bayesian inference, which for the first time…

Solar and Stellar Astrophysics · Physics 2015-06-18 Ralph Schönrich , Maria Bergemann

M subdwarfs are low-metallicity M dwarfs that typically inhabit the halo population of the Galaxy. Metallicity controls the opacity of stellar atmospheres; in metal poor stars, hydrostatic equilibrium is reached at a smaller radius, leading…

We consider the problem of downlink channel estimation for millimeter wave (mmWave) MIMO-OFDM systems, where both the base station (BS) and the mobile station (MS) employ large antenna arrays for directional precoding/beamforming. Hybrid…

Information Theory · Computer Science 2016-11-02 Zhou Zhou , Jun Fang , Linxiao Yang , Hongbin Li , Zhi Chen , Rick S. Blum

A library of 211 echelle spectra taken with ELODIE at the Observatoire de Haute-Provence is presented. It provides a set of spectroscopic standards covering the full range of gravities and metallicities in the effective temperature interval…

Astrophysics · Physics 2009-10-30 C. Soubiran , D. Katz , R. Cayrel

This paper concerns a spectral estimation problem in which we want to find a spectral density function that is consistent with estimated second-order statistics. It is an inverse problem admitting multiple solutions, and selection of a…

Optimization and Control · Mathematics 2019-08-08 Bin Zhu
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