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The Age-Redshift Relationship of Old Passive Galaxies | | Jun-Jie Wei
; Xue-Feng Wu
; Fulvio Melia
; Fa-Yin Wang
; Hai Yu
; | | Date: |
28 May 2015 | | Abstract: | We use 32 age measurements of passively evolving galaxies as a function of
redshift to test and compare the standard model ($Lambda$CDM) with the $R_{
m
h}=ct$ Universe. We show that the latter fits the data with a reduced
$chi^2_{
m dof}=0.435$ for a Hubble constant $H_{0}= 67.2_{-4.0}^{+4.5}$ km
$
m s^{-1}$ $
m Mpc^{-1}$. By comparison, the optimal flat $Lambda$CDM
model, with two free parameters (including $Omega_{
m
m}=0.12_{-0.11}^{+0.54}$ and $H_{0}=94.3_{-35.8}^{+32.7}$ km $
m s^{-1}$ $
m
Mpc^{-1}$), fits the age-emph{z} data with a reduced $chi^2_{
m dof}=0.428$.
Based solely on their $chi^2_{
m dof}$ values, both models appear to account
for the data very well, though the optimized $Lambda$CDM parameters are only
marginally consistent with those of the concordance model ($Omega_{
m
m}=0.27$ and $H_{0}= 70$ km $
m s^{-1}$ $
m Mpc^{-1}$). Fitting the age-$z$
data with the latter results in a reduced $chi^2_{
m dof}=0.523$. However,
because of the different number of free parameters in these models, selection
tools, such as the Akaike, Kullback and Bayes Information Criteria, favour
$R_{
m h}=ct$ over $Lambda$CDM with a likelihood of $sim 66.5\%-80.5\%$
versus $sim 19.5\%-33.5\%$. These results are suggestive, though not yet
compelling, given the current limited galaxy age-$z$ sample. We carry out Monte
Carlo simulations based on these current age measurements to estimate how large
the sample would have to be in order to rule out either model at a $sim
99.7\%$ confidence level. We find that if the real cosmology is $Lambda$CDM, a
sample of $sim 45$ galaxy ages would be sufficient to rule out $R_{
m h}=ct$
at this level of accuracy, while $sim 350$ galaxy ages would be required to
rule out $Lambda$CDM if the real Universe were instead $R_{
m h}=ct$. | | Source: | arXiv, 1505.7671 | | Services: | Forum | Review | PDF | Favorites | |
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