Can Cooling and Heating Functions be Modeled with Homogeneous Radiation Fields?

Kavli Affiliate: Nickolay Y. Gnedin

| First 5 Authors: David Robinson, Camille Avestruz, Nickolay Y. Gnedin, ,

| Summary:

Cooling and heating functions describe how radiative processes impact the
thermal state of a gas as a function of its temperature and other physical
properties. In a most general case the functions depend on the detailed
distributions of ionic species and on the radiation spectrum. Hence, these
functions may vary on a very wide range of spatial and temporal scales. In this
paper, we explore cooling and heating functions between $5leq z leq10$ in
simulated galaxies from the Cosmic Reionization On Computers (CROC) project. We
compare three functions. First, the actual cooling and heating rates of
hydrodynamic cells as a function of cell temperature. Second, the median
cooling and heating functions computed using median interstellar medium (ISM)
properties (median ISM). Last, the median of the cooling and heating functions
of all gas cells (instantaneous). We find that the median ISM and instantaneous
approaches to finding a median cooling and heating function give identical
results within the spread due to cell-to-cell variation. However, the actual
cooling (heating) rates experienced by the gas at different temperatures in the
simulations do not correspond to either summarized cooling (heating) functions.
In other words, the thermodynamics of the gas in the simulations cannot be
described by a single set of a cooling plus a heating function with a spatially
constant radiation field that could be computed with common tools, such as
Cloudy.

| Search Query: ArXiv Query: search_query=au:”Nickolay Y. Gnedin”&id_list=&start=0&max_results=10

Read More