Absorption Line Signatures of Gas in Mini Dark Matter Halos

Abstract

Recent observations and theoretical calculations suggest that some QSO absorption line systems may be due to gas in small dark matter halos with circular velocities on the order of 30 km/s. Additional observational evidence suggests that, in general, many absorption line systems may also be multi-phase in nature. Thus, computing the absorption lines of mini-halos, in addition to providing signatures of small halos, is a natural way to explore multi-phase behavior. The state of gas in mini-halos is strongly affected by the background UV radiation field. To address this issue a code was developed that includes many of the chemical and radiative processes found in CLOUDY and also incorporates spherically symmetric multi-wavelength radiative transfer of an isotropic field, non-equilibrium chemistry, heating, cooling and self-consistent quasi hydro-static equilibrium gas dynamics. With this code detailed simulations were conducted of gas in mini-halos using different types of background spectra. From these simulations the absorption line signatures of the gas were computed and compared with a variety of observations: high redshift metal lines, He lines and low redshift metal line systems. Based on these results the mini-halo model absorption line signatures appear to be consistent with many current observations given a sufficiently soft spectrum.

37 pages, 16 figures, accepted to the Astronomical Journal

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• Adaptive Ray Tracing for Radiative Transfer around Point Sources
• Physical Properties and Baryonic Content of Low-Redshift Intergalactic Ly-alpha and O VI Absorption Systems: The PG1116+215 Sight Line
• The Impact of Inhomogeneous Reionization on the Satellite Galaxy Population of the Milky Way
• MAGIICAT III. Interpreting Self-Similarity of the Circumgalactic Medium with Virial Mass using MgII Absorption
• Discovery of a Primitive Damped Lyman alpha Absorber Near an X-ray Bright Galaxy Group in the Virgo Cluster
• Numerical Simulations of High Redshift Star Formation in Dwarf Galaxies
• Metal-Ion Absorption in Conductively Evaporating Clouds
• Are Compact High-Velocity Clouds Extragalactic Objects?
• Damped Lyman alpha systems and galaxy formation models - II. High ions and Lyman limit systems
• A Limit on the Metallicity of Compact High Velocity Clouds
• Patchy He II reionization and the physical state of the IGM
• A Kennicutt-Schmidt Law for Intervening Absorption Line Systems
• Photoionized Gas in Dark-Matter Minihalos in the Galactic Halo and Local Group