THE AGE–REDSHIFT RELATIONSHIP OF OLD PASSIVE GALAXIES

Persistent Link:
http://hdl.handle.net/10150/615092
Title:
THE AGE–REDSHIFT RELATIONSHIP OF OLD PASSIVE GALAXIES
Author:
Wei, Jun-Jie; Wu, Xue-Feng; Melia, Fulvio; Wang, Fa-Yin; Yu, Hai
Affiliation:
The University of Arizona
Issue Date:
2015-07-07
Publisher:
IOP PUBLISHING LTD
Citation:
THE AGE–REDSHIFT RELATIONSHIP OF OLD PASSIVE GALAXIES 2015, 150 (1):35 The Astronomical Journal
Journal:
The Astronomical Journal
Rights:
© 2015. The American Astronomical Society. All rights reserved.
Collection Information:
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.
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 $R_{\rm h}=ct$ Universe. We show that the latter fits the data with a reduced $\chi^2_{\rm dof}=0.435$ for a Hubble constant $H_{0}= 67.2_{-4.0}^{+4.5}$ km $\rm s^{-1}$ $\rm Mpc^{-1}$. By comparison, the optimal flat $\Lambda$CDM model, with two free parameters (including $\Omega_{\rm m}=0.12_{-0.11}^{+0.54}$ and $H_{0}=94.3_{-35.8}^{+32.7}$ km $\rm s^{-1}$ $\rm Mpc^{-1}$), fits the age-\emph{z} data with a reduced $\chi^2_{\rm dof}=0.428$. Based solely on their $\chi^2_{\rm dof}$ 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 ($\Omega_{\rm m}=0.27$ and $H_{0}= 70$ km $\rm s^{-1}$ $\rm Mpc^{-1}$). Fitting the age-$z$ data with the latter results in a reduced $\chi^2_{\rm dof}=0.523$. However, because of the different number of free parameters in these models, selection tools, such as the Akaike, Kullback and Bayes Information Criteria, favour $R_{\rm h}=ct$ 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 $R_{\rm h}=ct$ at this level of accuracy, while $\sim 350$ galaxy ages would be required to rule out $\Lambda$CDM if the real Universe were instead $R_{\rm h}=ct$. This difference in required sample size reflects the greater number of free parameters available to fit the data with $\Lambda$CDM.
ISSN:
1538-3881
DOI:
10.1088/0004-6256/150/1/35
Version:
Final accepted manuscript
Additional Links:
http://stacks.iop.org/1538-3881/150/i=1/a=35?key=crossref.fd206a847a507970772890ba98a1a896

Full metadata record

DC FieldValue Language
dc.contributor.authorWei, Jun-Jieen
dc.contributor.authorWu, Xue-Fengen
dc.contributor.authorMelia, Fulvioen
dc.contributor.authorWang, Fa-Yinen
dc.contributor.authorYu, Haien
dc.date.accessioned2016-06-29T19:30:03Z-
dc.date.available2016-06-29T19:30:03Z-
dc.date.issued2015-07-07-
dc.identifier.citationTHE AGE–REDSHIFT RELATIONSHIP OF OLD PASSIVE GALAXIES 2015, 150 (1):35 The Astronomical Journalen
dc.identifier.issn1538-3881-
dc.identifier.doi10.1088/0004-6256/150/1/35-
dc.identifier.urihttp://hdl.handle.net/10150/615092-
dc.description.abstractWe use 32 age measurements of passively evolving galaxies as a function of redshift to test and compare the standard model ($\Lambda$CDM) with the $R_{\rm h}=ct$ Universe. We show that the latter fits the data with a reduced $\chi^2_{\rm dof}=0.435$ for a Hubble constant $H_{0}= 67.2_{-4.0}^{+4.5}$ km $\rm s^{-1}$ $\rm Mpc^{-1}$. By comparison, the optimal flat $\Lambda$CDM model, with two free parameters (including $\Omega_{\rm m}=0.12_{-0.11}^{+0.54}$ and $H_{0}=94.3_{-35.8}^{+32.7}$ km $\rm s^{-1}$ $\rm Mpc^{-1}$), fits the age-\emph{z} data with a reduced $\chi^2_{\rm dof}=0.428$. Based solely on their $\chi^2_{\rm dof}$ 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 ($\Omega_{\rm m}=0.27$ and $H_{0}= 70$ km $\rm s^{-1}$ $\rm Mpc^{-1}$). Fitting the age-$z$ data with the latter results in a reduced $\chi^2_{\rm dof}=0.523$. However, because of the different number of free parameters in these models, selection tools, such as the Akaike, Kullback and Bayes Information Criteria, favour $R_{\rm h}=ct$ 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 $R_{\rm h}=ct$ at this level of accuracy, while $\sim 350$ galaxy ages would be required to rule out $\Lambda$CDM if the real Universe were instead $R_{\rm h}=ct$. This difference in required sample size reflects the greater number of free parameters available to fit the data with $\Lambda$CDM.en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/1538-3881/150/i=1/a=35?key=crossref.fd206a847a507970772890ba98a1a896en
dc.rights© 2015. The American Astronomical Society. All rights reserved.en
dc.titleTHE AGE–REDSHIFT RELATIONSHIP OF OLD PASSIVE GALAXIESen
dc.typeArticleen
dc.contributor.departmentThe University of Arizonaen
dc.identifier.journalThe Astronomical Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal accepted manuscripten
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