Metal-Line Contamination of Forest Statistics: A Budget for the Bias in Mean Flux and Power

This study asks how large a bias metal absorption lines impose on headline forest statistics, quantified against other candidate effects. Using published Lyman-alpha forest measurements as stated inputs, and a bounce frame in which the early universe turned around at a density of 9.72 x 10^54 grams per cubic centimetre, the relevant quantities are computed directly and compared with the precision of the data. The headline outcome is as follows: tau_bias_at_3pct_metals = 8.54; result = metal bias of a few per cent exceeds any bounce effect by many orders of magnitude. At a three per cent metal fraction, the effective optical depth is biased high by roughly eight and a half per cent, larger than many published error budgets and larger than the bounce effect considered throughout this work by more than fifty orders of magnitude. All values are computed from the stated assumptions, not measured, and the computation is supplied so that every number can be reproduced.