Age-dating luminous red galaxies observed with the Southern African Large Telescope

作者：Ratsimbazafy, A. L.^*; Loubser, S. I.^*; Crawford, S. M.^*; Cress, C. M.; Bassett, B. A.; Nichol, R. C.; Vaisanen, P.

来源：Monthly Notices of the Royal Astronomical Society, 2017, 467(3): 3239-3254.

DOI：10.1093/mnras/stx301

• galaxies: elliptical and lenticular
• cD-galaxies: evolution
• cosmological parameters
• cosmology: observations

We measure a value for the cosmic expansion ofH(z)= 89 +/- 23(stat) +/- 44(syst) kms(-1) Mpc(-1) at a redshift of z similar or equal to 0.47 based on the differential age technique. This technique, also known as cosmic chronometers, uses the age difference between two redshifts for a passively evolving population of galaxies to calculate the expansion rate of the Universe. Our measurement is based on the analysis of high-quality spectra of luminous red galaxies obtained with the Southern African Large Telescope in two narrow redshift ranges of z similar or equal to 0.40 and 0.55 as part of an initial pilot study. Ages were estimated by fitting single stellar population models to the observed spectra. This measurement presents one of the best estimates of H(z) via this method at z similar to 0.5 to date.

• 出版日期2017-6
• 单位西北大学