MEAN-FLUX-REGULATED PRINCIPAL COMPONENT ANALYSIS CONTINUUM FITTING OF SLOAN DIGITAL SKY SURVEY Lyα FOREST SPECTRA

Continuum fitting is an important aspect of Lyman-alpha forest science, since errors in the estimated optical depths scale with the fractional continuum error. However, traditional methods of estimating continua in noisy and moderate-resolution spectra (S/N 5. The residual Fourier power in the continuum is decreased by a factor of a few in comparison with dividing by the mean continuum, enabling Lyman-alpha flux power spectrum measurements to be extended to ~2x larger scales. Using this new technique, we make available continuum fits for 12,069 z>2.3 Lyman-alpha forest spectra from SDSS DR7 for use by the community. This technique is also applicable to future releases of the ongoing BOSS survey, which is obtaining spectra for ~ 150,000 Lyman-alpha forest spectra at low signal-to-noise (S/N ~ 2).