School of Astronomy (SoA) - Weekly Seminar

Different Methods of Determining Quasar Continuum in the Lyman-alpha Forest  

It is believed that most of the ordinary baryonic matter, at high redshift, is found  in the Inter-Galactic Medium (IGM). The IGM and its physical properties can be studied using the imprint left in the spectra of background quasars, the so-called Lyman-alpha forest. The main goal in studying the Lyman-alpha forest in quasar spectra is to determine the underlying matter distribution in the IGM. One of the key parameters is the total amount of absorption by neutral Hydrogen. In order to measure this absorption we must first determine the quasar continuum in the Lyman-alpha forest. This is not obvious especially at low spectral resolution and high redshift where there is little unabsorbed continuum remaining in the Lyman-alpha forest. After reviewing the subject, I will represent some reports on our recent efforts to determine the quasar continuum in the Lyman-alpha forest with different methods, including Principal Component Analysis, Artificial Neural Network, and Wavelet Analysis methods. 

IPM Larak Building, School of Astronomy