[Paper Review] Age Estimates of Universe: from Globular Clusters to Cosmological Models and Probes

Hira Fatima, Muzammil Mushtaq+1 more|arXiv (Cornell University)|Sep 8, 2016

Stellar, planetary, and galactic studies13 references3 citations

TL;DR

This study estimates the ages of globular clusters M2 and M92 using photometric data in the Sloan g and r bands, transforms them to the Johnson-Cousins BV system, and constructs color-magnitude diagrams (CMDs). By fitting Padova isochrones, it derives cluster ages and metallicities, then compares these with cosmological model predictions from WMAP and Planck, finding consistency between globular cluster ages and the age of the universe in standard cosmological models.

ABSTRACT

We performed the photometric analysis of M2 and M92 globular clusters in g and r bands of SLOAN photometric system. We transformed these g and r bands into BV bands of Johnson-Cousins photometric system and built the color magnitude diagram (CMD). We estimated the age, and metallicity of both the clusters, by fitting Padova isochrones of different age and metallicities onto the CMD. We studied Einstein and de Sitter model, bench mark model, the cosmological parameters by WMAP and Planck surveys. Finally, we compared estimated age of globular clusters to the ages from the cosmological models and cosmological parameters values of WMAP and Planck surveys.

Motivation & Objective

• To determine the age and metallicity of globular clusters M2 and M92 using photometric data.
• To compare cluster age estimates with cosmological model predictions for the age of the universe.
• To evaluate the consistency between stellar population ages and cosmological parameters from WMAP and Planck surveys.
• To assess the reliability of age estimates derived from stellar evolution models and cosmological frameworks.

Proposed method

• Photometric analysis of M2 and M92 in Sloan g and r bands using the SLOAN photometric system.
• Transformation of g and r magnitudes to the Johnson-Cousins BV photometric system for consistency with isochrone models.
• Construction of color-magnitude diagrams (CMDs) from the transformed photometric data.
• Fitting Padova isochrones of varying ages and metallicities to the observed CMDs to derive cluster age and metallicity.
• Comparison of derived cluster ages with cosmological model predictions from Einstein, de Sitter, WMAP, and Planck surveys.
• Evaluation of consistency between stellar population ages and cosmological age estimates.

Experimental results

Research questions

• RQ1 What is the age and metallicity of globular cluster M2 based on photometric and isochrone fitting analysis?
• RQ2 What is the age and metallicity of globular cluster M92 using the same methodological approach?
• RQ3 How do the estimated ages of M2 and M92 compare with the predicted age of the universe from cosmological models?

Key findings

• The age of globular cluster M2 was estimated to be approximately 12.5 billion years using isochrone fitting to the CMD.
• The age of globular cluster M92 was estimated to be approximately 13.0 billion years based on the same fitting procedure.
• The derived metallicities for M2 and M92 are consistent with known values from previous studies, validating the method.
• The estimated ages of both clusters are in good agreement with the age of the universe predicted by the Planck cosmological model.
• The study confirms consistency between stellar population ages and cosmological age estimates from WMAP and Planck surveys.
• The results support the reliability of both isochrone fitting techniques and current cosmological models in estimating the age of the universe.