Comparative studies of Population Synthesis Models in the frame work of   modified Str\"{o}mgren filters
  Evolutionary models form a vital part of stellar population research to understand their evolution, but despite their long history of development, they often misrepresent and misinterpret the properties of stellar population observed through broadband and spectroscopic measurements. With the growing numbers of these synthesis models, model comparison becomes an important analysis to choose a suitable model for upgrade. Along with the model comparison, we reinvestigate the technique of modified Str\"omgren photometry to measure reliable parameter-sensitive colours and estimate precise model ages and metallicities. The assessment of Rakos/Schulz models with GALEV and Worthey's Lick/IDS model find smaller colour variation: \Delta(uz-vz) $\leq$ 0.056, \Delta(bz-yz) $\leq$ -0.05 and \Delta(vz-yz) $\leq$ 0.061. The study conveys a good agreement of GALEV models with the modified Str\"omgren colours but with poor UV model predictions with the observed globular cluster data, while the spectroscopic models perform badly due to the use of older isochrone and stellar spectral libraries with inaccurate/insufficient knowledge of various stellar phases and their treatment. Overall, the assessment finds modified Str\"omgren photometry well suited to study different types stellar populations by mitigating the effects of the age-metallicity degeneracy. 
Yuvraj Harsha Sreedhar, Karl Rakos, Gerhard Hensler
astro-ph.GA