2016MNRAS.459.3234S -
Mon. Not. R. Astron. Soc., 459, 3234-3250 (2016/July-1)
Physical conditions in three high-z H2-bearing DLAs: implications for grain size.
SHAW G., RAWLINS K. and SRIANAND R.
Abstract (from CDS):
We present results of our numerical simulation of three H2-bearing damped Lyman α absorbers (DLAs) in the redshift interval ∼ 2-3. The systems we have modelled are the DLAs at zabs=2.3377 towards the quasar LBQS 1232 + 0815, at zabs=2.418 37 towards SDSS J143912.04 + 111740.5 and at zabs=2.6265 towards FBQS J081240.6 + 320808. We have used the spectral synthesis code cloudy to simulate the physical environment of these DLAs, and constrain the density, radiation field, geometry and dust-grain properties of the DLAs self-consistently based on the observed column densities of various atomic and molecular species such as H i, fine structure lines of C i and the rotational level population of H2. In our models, we explore the effect of grain size distribution on the predicted column densities of different species. Within the allowed uncertainties in the inferred dust-to-gas ratio, both models with standard interstellar medium grains and smaller sized grains reproduce the observations equally well. Improved constraints on dust-to-gas ratio and line-of-sight extinction are important for probing the grain size distribution in high-z DLAs. We find the H2-bearing clouds to have line-of-sight thickness in the range 1-6 pc, consistent with what has been found using partial coverage or 21-cm observations in some high-z DLAs.
Abstract Copyright:
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
methods: numerical - dust extinction - ISM: molecules - intergalactic medium - quasars: absorption lines - quasars: absorption lines
Simbad objects:
6
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