부산대학교 도서관

As a test of the time symmetry of forbidden-line emission processes, we measured the [OIII] λ λ 4959 and 5007 emission lines of more than 12,000 galaxies from the Sloan Digital Sky Survey DR8 to examine the [OIII] λ λ 4959,5007 flux ratio as a function of redshift z. Using two different approaches, we fitted each line with a Gaussian curve and rejected any spectrum not conforming to requirements of line symmetry, S/N levels, and continuum fit. We found the variance in the ratio of flux to be between 4.7 and −3.3% for 0 < z < 0.433 which is consistent with no change. After correcting for systematic effects of noise, we found the mean value of the [OIII] λ λ 4959,5007 flux ratio to be 2.98 ± 0.01 which is consistent with theory and previous studies using AGN spectra. We also used these data to estimate an upper limit on the time dependence of the fine structure constant α of Δ α / α (0) < 1.4 × 10 − 5 for galaxies within the same redshift range. This corresponds to | α − 1 d α / d t | < 2 × 10 − 15 yr − 1 , which is also in line with previous estimates from SDSS QSO data. [ABSTRACT FROM AUTHOR]