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

A. L. Ratsimbazafy; S. I. Loubser; S. M. Crawford; C. M. Cress; B. A. Bassett; R. C. Nichol; P. Väisänen

doi:10.1093/mnras/stx301

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

A. L. Ratsimbazafy, S. I. Loubser, S. M. Crawford, C. M. Cress, B. A. Bassett, R. C. Nichol, P. Väisänen

Institute of Cosmology & Gravitation

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Abstract

We measure a value for the cosmic expansion of H(z)=89±23(stat) ± 44(syst) km s⁻¹ Mpc⁻¹ at a redshift of z≃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 analysis of high quality spectra of Luminous Red Galaxies (LRGs) obtained with the Southern African Large Telescope (SALT) in two narrow redshift ranges of z≃0.40 and z≃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∼0.5 to date.

Original language	English
Pages (from-to)	3239-3254
Number of pages	16
Journal	Monthly Notices of the Royal Astronomical Society
Volume	467
Issue number	3
DOIs	https://doi.org/10.1093/mnras/stx301
Publication status	Published - 6 Feb 2017

Keywords

galaxies: elliptical and lenticular, cD
galaxies: evolution
cosmological parameters
cosmology: observations

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10.1093/mnras/stx301

Age-dating luminous red galaxies
This article has been accepted for publication in MNRAS ©: 2017 A. L. Ratsimbazafy et al. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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Cite this

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title = "Age-dating luminous red galaxies observed with the Southern African Large Telescope",

abstract = "We measure a value for the cosmic expansion of H(z)=89±23(stat) ± 44(syst) km s−1 Mpc−1 at a redshift of z≃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 analysis of high quality spectra of Luminous Red Galaxies (LRGs) obtained with the Southern African Large Telescope (SALT) in two narrow redshift ranges of z≃0.40 and z≃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∼0.5 to date.",

keywords = "galaxies: elliptical and lenticular, cD, galaxies: evolution, cosmological parameters, cosmology: observations",

author = "Ratsimbazafy, {A. L.} and Loubser, {S. I.} and Crawford, {S. M.} and Cress, {C. M.} and Bassett, {B. A.} and Nichol, {R. C.} and P. V{\"a}is{\"a}nen",

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doi = "10.1093/mnras/stx301",

language = "English",

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T1 - Age-dating luminous red galaxies observed with the Southern African Large Telescope

AU - Ratsimbazafy, A. L.

AU - Loubser, S. I.

AU - Crawford, S. M.

AU - Cress, C. M.

AU - Bassett, B. A.

AU - Nichol, R. C.

AU - Väisänen, P.

PY - 2017/2/6

Y1 - 2017/2/6

N2 - We measure a value for the cosmic expansion of H(z)=89±23(stat) ± 44(syst) km s−1 Mpc−1 at a redshift of z≃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 analysis of high quality spectra of Luminous Red Galaxies (LRGs) obtained with the Southern African Large Telescope (SALT) in two narrow redshift ranges of z≃0.40 and z≃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∼0.5 to date.

AB - We measure a value for the cosmic expansion of H(z)=89±23(stat) ± 44(syst) km s−1 Mpc−1 at a redshift of z≃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 analysis of high quality spectra of Luminous Red Galaxies (LRGs) obtained with the Southern African Large Telescope (SALT) in two narrow redshift ranges of z≃0.40 and z≃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∼0.5 to date.

KW - galaxies: elliptical and lenticular, cD

KW - galaxies: evolution

KW - cosmological parameters

KW - cosmology: observations

U2 - 10.1093/mnras/stx301

DO - 10.1093/mnras/stx301

M3 - Article

SN - 0035-8711

VL - 467

SP - 3239

EP - 3254

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 3

ER -

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

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Keywords

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