Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı



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Estimation of Luminosity Functıon with Photometric Redshıft Method

Obtaining redshifts of galaxies plays an important role in cosmology studies. With help of redshift values, radial velocities of galaxies and galaxy clusters can be found. This leads to the expanding velocity of the universe. This is one of the most important subjects in observational cosmology. Expanding velocity of the universe gives us information about matter density which affect the fate of the universe. Therefore, estimating redshift values with a high accuracy is very important issue in cosmology.

In this thesis, photometric redshift estimation method as one of the methods for redshift estimation was described. After a brief history and development, application of the method was described. Advantages and disadvantages of the method were given comparing to the spectroscopic method.

Photometric data of Abell 2040 galaxy cluster are taken from Sloan Digital Sky Survey (SDSS) and using Le PHARE software photometric redshifts of the cluster are calculated. Comparing the results in the literature, redshift of the cluster is estimated with an error of Δz=0,051. According to this redshift, distance of the Abell 2040 is found as 424,3 Mpc.

Luminosity function of the cluster could be constructed up to Mg = -20,5 magnitude completely. Obtained luminosity function of the cluster is in well agreement with luminosity functions in the literature. Number of galaxies increase towards faint magnitudes can be seen clearly in the graphs. At the bright end of luminosity function of the cluster there is one galaxy which is probably the central dominated galaxy of the cluster. In Dressler’s (1980) list this galaxy was listed as the D type galaxy which is very concordant with this thought.
GÜNEŞ Orhan
Danışman : Doç.Dr. Yüksel KARATAŞ

Anabilim Dalı : Astronomi ve Uzay Bilimleri

Mezuniyet Yılı : 2008

Tez Savunma Jürisi : Doç.Dr. Yüksel KARATAŞ

Prof.Dr. H. Gökmen TEKTUNALI

Prof.Dr. H. Hüseyin MENTEŞE

Doç.Dr. A. Talat SAYGAÇ,

Yard.Doç.Dr. Saffettin YILDIRIM





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