%0 Generic %1 finlator2014reionisation %A Finlator, K. %A Thompson, R. %A Huang, S. %A Davé, R. %A Zackrisson, E. %A Oppenheimer, B. D. %D 2014 %K carbon reionisation simulation %T The Reionisation of Carbon %U http://arxiv.org/abs/1412.4810 %X Observations suggest that CII was more abundant than CIV in the intergalactic medium towards the end of the hydrogen reionisation epoch. This transition provides a unique opportunity to study the enrichment history of intergalactic gas and the growth of the ionising background (UVB) at early times. We study how carbon absorption evolves from z=10-5 using a cosmological hydrodynamic simulation that includes a self-consistent multifrequency UVB as well as a well-constrained model for galactic outflows to disperse metals. Our predicted UVB is within 2-4 times that of Haardt & Madau (2012), which is fair agreement given the uncertainties. Nonetheless, we use a calibration in post-processing to account for Lyman-alpha forest measurements while preserving the predicted spectral slope and inhomogeneity. The UVB fluctuates spatially in such a way that it always exceeds the volume average in regions where metals are found. This implies both that a spatially-uniform UVB is a poor approximation and that metal absorption is not sensitive to the epoch when HII regions overlap globally even at column densites of 10^12 cm^-2. We find, consistent with observations, that the CII mass fraction drops to low redshift while CIV rises owing the combined effects of a growing UVB and continued addition of carbon in low-density regions. This is mimicked in absorption statistics, which broadly agree with observations at z=6-3 while predicting that the absorber column density distributions rise steeply to the lowest observable columns. Our model reproduces the large observed scatter in the number of low-ionisation absorbers per sightline, implying that the scatter does not indicate a partially-neutral Universe at z=6.

@misc{finlator2014reionisation, abstract = {Observations suggest that CII was more abundant than CIV in the intergalactic medium towards the end of the hydrogen reionisation epoch. This transition provides a unique opportunity to study the enrichment history of intergalactic gas and the growth of the ionising background (UVB) at early times. We study how carbon absorption evolves from z=10-5 using a cosmological hydrodynamic simulation that includes a self-consistent multifrequency UVB as well as a well-constrained model for galactic outflows to disperse metals. Our predicted UVB is within 2-4 times that of Haardt & Madau (2012), which is fair agreement given the uncertainties. Nonetheless, we use a calibration in post-processing to account for Lyman-alpha forest measurements while preserving the predicted spectral slope and inhomogeneity. The UVB fluctuates spatially in such a way that it always exceeds the volume average in regions where metals are found. This implies both that a spatially-uniform UVB is a poor approximation and that metal absorption is not sensitive to the epoch when HII regions overlap globally even at column densites of 10^{12} cm^{-2}. We find, consistent with observations, that the CII mass fraction drops to low redshift while CIV rises owing the combined effects of a growing UVB and continued addition of carbon in low-density regions. This is mimicked in absorption statistics, which broadly agree with observations at z=6-3 while predicting that the absorber column density distributions rise steeply to the lowest observable columns. Our model reproduces the large observed scatter in the number of low-ionisation absorbers per sightline, implying that the scatter does not indicate a partially-neutral Universe at z=6.}, added-at = {2014-12-17T09:29:31.000+0100}, author = {Finlator, K. and Thompson, R. and Huang, S. and Davé, R. and Zackrisson, E. and Oppenheimer, B. D.}, biburl = {https://www.bibsonomy.org/bibtex/2dabb4420e20a5260472cd3b3b4f6698b/miki}, description = {[1412.4810] The Reionisation of Carbon}, interhash = {8c0007a1b1eaa7342154fd6e2abce986}, intrahash = {dabb4420e20a5260472cd3b3b4f6698b}, keywords = {carbon reionisation simulation}, note = {cite arxiv:1412.4810Comment: 16 pages, 14 figures, accepted to MNRAS}, timestamp = {2014-12-17T09:29:31.000+0100}, title = {The Reionisation of Carbon}, url = {http://arxiv.org/abs/1412.4810}, year = 2014 }