Accelerating BAO scale fitting using Taylor series

ABSTRACT The Universe is currently undergoing accelerated expansion driven by dark energy. Dark energy’s essential nature remains mysterious: one means of revealing it measuring the Universe’s size at different redshifts. This may be done using baryon acoustic oscillation (BAO) feature, a standard ruler in galaxy two-point correlation function (2PCF). In order to measure distance scale, dilates and contracts template for 2PCF fiducial cosmology, scaling factor ?. method finding best-fitting ? compute likelihood over grid roughly 100 values it. approach slow; this work, we propose significantly faster way. Our writes as polynomial Taylor-expanding about = 1, exploiting that know cosmology sufficiently well within few per cent unity. resulting from then analytically solved 48–85× than directly comparable which numerically minimize ?, ?12 000× iterative method. work will highly enabling upcoming large-scale structure redshift surveys such Energy Spectroscopic Instrument.