Abstract
We present the results of spectroscopic analysis of seven new H2-bearing damped Ly- systems in redshift range z=2.5 − 3. These systems were originally selected from SDSS catalog using a direct search for H2 and followed up with X-SHOOTER spectrograph at 8-m Very Large Telescope observatory. We measured the column densities of HI, H2 on various rotational levels, and metals species in different ionization stages and excitation levels. We used the rotational excitation of H2 molecules together with the fine-structure levels of neutral carbon to constrain the physical conditions in the associated medium. We found typical values for the kinetic temperature T ∼ 80 − 120 K, hydrogen density nH ∼ 30 − 400 cm−3 and UV radiation field ξUV ∼ 0.4 − 5 times of the Draine field. These values along with estimated thermal pressure are in agreement with expected values from the theoretical calculation of the cold neutral interstellar medium.
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