%0 Generic %1 howard2017simulating %A Howard, Corey S. %A Pudritz, Ralph E. %A Harris, Bill E. %A Klessen, Ralf S. %D 2017 %K GMC UV escape fraction %T Simulating the UV Escape Fractions from Molecular Cloud Populations in Star-forming Dwarf and Spiral Galaxies %U http://arxiv.org/abs/1710.04283 %X The escape of ultraviolet photons from the densest regions of the interstellar medium (ISM) --- Giant Molecular Clouds (GMCs) --- is a poorly constrained parameter which is vital to understanding the ionization of the ISM and the intergalactic medium. We characterize the escape fraction, f$_esc,GMC$, from a suite of individual GMC simulations with masses in the range 10$^4-6$ M$_ødot$ using the adaptive-mesh refinement code FLASH. We find significantly different f$_esc,GMC$ depending on the GMC mass which can reach $>$90\% in the evolution of 5$\times$10$^4$ and 10$^5$ M$_ødot$ clouds or remain low at $\sim$5\% for most of the lifetime of more massive GMCs. All clouds show fluctuations over short, sub-Myr timescales produced by flickering HII regions. We combine our results to calculate the total escape fraction (f$_esc,tot$) from GMC populations in dwarf starburst and spiral galaxies by randomly drawing clouds from a GMC mass distribution (dN/dM$\propto$M$^\alpha$, where $\alpha$ is either -1.5 or -2.5) over fixed time intervals. We find typical f$_esc,tot$ values of 8\% for both the dwarf and spiral models. The fluctuations of f$_esc,tot$, however, are much larger for the dwarf models with values as high as 90\%. The photons escaping from the 5$\times$10$^4$ and 10$^5$ M$_ødot$ GMCs are the dominant contributors to f$_esc,tot$ in all cases. We also show that the accompanying star formation rates (SFRs) of our model ($\sim$2$\times$10$^-2$ and 0.73 M$_ødot$yr$^-1$) are consistent with observations of SFRs in dwarf starburst and spiral galaxies, respectively.

@misc{howard2017simulating, abstract = {The escape of ultraviolet photons from the densest regions of the interstellar medium (ISM) --- Giant Molecular Clouds (GMCs) --- is a poorly constrained parameter which is vital to understanding the ionization of the ISM and the intergalactic medium. We characterize the escape fraction, f$_{\text{esc,GMC}}$, from a suite of individual GMC simulations with masses in the range 10$^{4-6}$ M$_{\odot}$ using the adaptive-mesh refinement code FLASH. We find significantly different f$_{\text{esc,GMC}}$ depending on the GMC mass which can reach $>$90\% in the evolution of 5$\times$10$^4$ and 10$^{5}$ M$_{\odot}$ clouds or remain low at $\sim$5\% for most of the lifetime of more massive GMCs. All clouds show fluctuations over short, sub-Myr timescales produced by flickering HII regions. We combine our results to calculate the total escape fraction (f$_{\text{esc,tot}}$) from GMC populations in dwarf starburst and spiral galaxies by randomly drawing clouds from a GMC mass distribution (dN/dM$\propto$M$^{\alpha}$, where $\alpha$ is either -1.5 or -2.5) over fixed time intervals. We find typical f$_{\text{esc,tot}}$ values of 8\% for both the dwarf and spiral models. The fluctuations of f$_{\text{esc,tot}}$, however, are much larger for the dwarf models with values as high as 90\%. The photons escaping from the 5$\times$10$^4$ and 10$^{5}$ M$_{\odot}$ GMCs are the dominant contributors to f$_{\text{esc,tot}}$ in all cases. We also show that the accompanying star formation rates (SFRs) of our model ($\sim$2$\times$10$^{-2}$ and 0.73 M$_{\odot}$yr$^{-1}$) are consistent with observations of SFRs in dwarf starburst and spiral galaxies, respectively.}, added-at = {2017-10-13T10:24:19.000+0200}, author = {Howard, Corey S. and Pudritz, Ralph E. and Harris, Bill E. and Klessen, Ralf S.}, biburl = {https://www.bibsonomy.org/bibtex/28bca455c993e8d93c47b8845aeecb427/miki}, description = {[1710.04283] Simulating the UV Escape Fractions from Molecular Cloud Populations in Star-forming Dwarf and Spiral Galaxies}, interhash = {eb9eef3defbf6a4d0b0d700394d4ffe7}, intrahash = {8bca455c993e8d93c47b8845aeecb427}, keywords = {GMC UV escape fraction}, note = {cite arxiv:1710.04283Comment: 14 pages, 7 figures, submitted to MNRAS}, timestamp = {2017-10-13T10:24:19.000+0200}, title = {Simulating the UV Escape Fractions from Molecular Cloud Populations in Star-forming Dwarf and Spiral Galaxies}, url = {http://arxiv.org/abs/1710.04283}, year = 2017 }