Abstract: QSOSIM uses a set of basic parameters (the magnitude, the redshift, and the spectral index) to simulate realistic high-resolution quasar spectra. The simulated spectra include physical effects seen in the real data: the power-law quasar continuum, the narrow and broad emission lines, absorption by neutral hydrogen (HI) in the Lyman alpha forest, and heavy element transitions along the line of sight. The code uses empirical HI column density, redshift, and b-parameter distributions to simulate absorption in the Lyman alpha forest. All absorbers with column densities larger than log [N(HI)/cm<sup>2</sup>]>17 have heavy element absorption, for which the column densities are calculated using the plasma simulation code CLOUDY and the radiative transfer code CUBA. The code also simulates the clustering of the intergalactic medium along the line of sight, the proximity effect of the quasar, and the effect of the cosmic ultraviolet background. Each simulated spectrum is saved in a single FITS file in as a noiseless R=100000 spectrum, as well as a spectrum convolved with Sloan Digital Sky Survey resolution (R=10000) and realistic noise.
Credit: Milakovic, Dinko; Webb, John K.