A wavelet analysis of QSO spectra
نویسندگان
چکیده
The temperature of the intergalactic medium (IGM) is an important factor in determining the line-widths of the absorption lines in the Lyα forest. We present a method to characterise the line-widths distribution using a decomposition of a Lyα spectrum in terms of discrete wavelets. Such wavelets form an orthogonal basis so the decomposition is unique. We demonstrate using hydrodynamic simulations that the mean and dispersion of the wavelet amplitudes is strongly correlated with both the temperature of the absorbing gas and its dependence on the gas density. Since wavelets are also localised in space, we are able to analyse the temperature distribution as a function of position along the spectrum. We illustrate how this method could be used to identify fluctuations in the IGM temperature which might result from late reionization or local effects.
منابع مشابه
A WAVELET-BASED PROCEDURE FOR MINING OF PULSE-LIKE GROUND MOTIONS FEATURES ON RESPONSE SPECTRA
The main objective of this paper is to present a wavelet-based procedure to characterize principle features of a special class of motions called pulse-like ground motions. Initially, continues wavelet transform (CWT) which has been known as a powerful technique both in earthquake engineering and seismology field is applied easily in automated detecting of strong pulse of earthquakes. In this pr...
متن کاملIsogeometric analysis: vibration analysis, Fourier and wavelet spectra
This paper presents the Fourier and wavelet characterization of vibratio...
متن کاملSpectroscopic detection of quasars in the 2dF Galaxy Redshift Survey
The 100,000 spectra from the 2 degree Field Galaxy Redshift Survey (2dFGRS) in the 100k Public Data Release represent the largest single compilation of galaxy spectra available. By virtue of its sheer size and the properties of the photometric catalogue that defines the sample, the 2dFGRS is expected to contain a number of potentially interesting objects other than galaxies. A search of the spe...
متن کاملDetecting the non-Gaussian Spectrum of QSO’s Lyα Absorption Line Distribution
We present an analysis of the non-Gaussianity in the distribution of Lyα forest lines in the QSO absorption spectra. Statistical tests performed on this data indicate that there may be large scale structure even though the power spectrum of the Lyα line distribution on large scales is found to be flat. It is apparent that higher (than two) order statistics are crucial in quantifying the cluster...
متن کاملRemoval of Methylene Blue, Malachite Green and Rhodamine B in a Ternary System by Pistachio Hull; Application of Wavelet Neural Network Modeling and Doehlert Design
Most of previous papers in the field of dye removal used one dye or dyes with nearly separate spectra that simplifies dyes concentration determination by Beer's law at different λmax. In many real situations, dyes with highly overlapped spectra exist and their concentrations can be determined by multivariate analysis methods. In this study, principal component-wavelet neural network (PC-WNN) wa...
متن کامل