• Chemical evolution of the high redshift galaxies

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    • Keywords


      High redshift galaxies; chemical evolution; Lyman limitsystems; CIV absorption systems; diffuse UV radiation background

    • Abstract


      We have tried to determine the rate of chemical evolution of high redshift galaxies from the observed redshift distribution of the heavy element absorption systems in the spectra of QSOs, taking into account the evolution in the intensity of the metagalactic UV ionizing radiation background, the radius and/or the co-moving number density of, and the fraction of mass in the form of gas in, the absorbers. The data for both the Lyman limit systems and the C IV systems have been fitted simultaneously. It seems that the abundance of carbon has possibly increased by about a factor of 5 to 20 from the cosmic time corresponding to the redshift ≃ 4 to 2. The data also suggest that either the radius or the co-moving number density of the galaxies increased with redshift up to z = 2.0 and decreased slowly thereafter. The total mass of the halo gas was higher in the past, almost equal to the entire mass of the galaxy at z = 4. The hydrogen column density distribution for Lyman limit systems predicted by the model is in agreement with the observed distribution.

    • Author Affiliations


      Pushpa Khare1 2 N. C. Rana1

      1. Inter University Centre for Astronomy and Astrophysics, Ganeshkhind, Post Bag 4, Pune - 411 007
      2. Physics Department, Utkal University, Bhubaneswar - 751004
    • Dates

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