%0 Generic %1 accurso2016radiative %A Accurso, Gioacchino %A Saintonge, Amélie %A Bisbas, Thomas. G. %A Viti, Serena %D 2016 %K [CII] origin radiative transfer %T Radiative Transfer meets Bayesian statistics: where does your Galaxy's CII come from? %U http://arxiv.org/abs/1607.03488 %X The CII 158$\mu$m emission line can arise in all phases of the ISM, therefore being able to disentangle the different contributions is an important yet unresolved problem when undertaking galaxy-wide, integrated CII observations. We present a new multi-phase 3D radiative transfer interface that couples Starburst99, a stellar spectrophotometric code, with the photoionisation and astrochemistry codes Mocassin and 3D-PDR. We model entire star forming regions, including the ionised, atomic and molecular phases of the ISM, and apply a Bayesian inference methodology to parametrise how the fraction of the CII emission originating from molecular regions, $f_CII,mol$, varies as a function of typical integrated properties of galaxies in the local Universe. The main parameters responsible for the variations of $f_CII,mol$ are specific star formation rate (sSFR), gas phase metallicity, HII region electron number density ($n_e$), and dust mass fraction. For example, $f_CII,mol$ can increase from 60% to 80% when either $n_e$ increases from 10$^1.5$ to 10$^2.5$cm$^-3$, or SSFR decreases from $10^-9.6$ to $10^-10.6$ yr$^-1$. Our model predicts for the Milky Way that $f_CII,mol$$=75.8\pm5.9$%, in agreement with the measured value of 75%. When applying the new prescription to a complete sample of galaxies from the Herschel Reference Survey (HRS), we find that anywhere from 60 to 80% of the total integrated CII emission arises from molecular regions.

@misc{accurso2016radiative, abstract = {The [CII] 158$\mu$m emission line can arise in all phases of the ISM, therefore being able to disentangle the different contributions is an important yet unresolved problem when undertaking galaxy-wide, integrated [CII] observations. We present a new multi-phase 3D radiative transfer interface that couples Starburst99, a stellar spectrophotometric code, with the photoionisation and astrochemistry codes Mocassin and 3D-PDR. We model entire star forming regions, including the ionised, atomic and molecular phases of the ISM, and apply a Bayesian inference methodology to parametrise how the fraction of the [CII] emission originating from molecular regions, $f_{[CII],mol}$, varies as a function of typical integrated properties of galaxies in the local Universe. The main parameters responsible for the variations of $f_{[CII],mol}$ are specific star formation rate (sSFR), gas phase metallicity, HII region electron number density ($n_e$), and dust mass fraction. For example, $f_{[CII],mol}$ can increase from 60% to 80% when either $n_e$ increases from 10$^{1.5}$ to 10$^{2.5}$cm$^{-3}$, or SSFR decreases from $10^{-9.6}$ to $10^{-10.6}$ yr$^{-1}$. Our model predicts for the Milky Way that $f_{[CII],mol}$$=75.8\pm5.9$%, in agreement with the measured value of 75%. When applying the new prescription to a complete sample of galaxies from the Herschel Reference Survey (HRS), we find that anywhere from 60 to 80% of the total integrated [CII] emission arises from molecular regions.}, added-at = {2016-07-14T10:53:36.000+0200}, author = {Accurso, Gioacchino and Saintonge, Amélie and Bisbas, Thomas. G. and Viti, Serena}, biburl = {https://www.bibsonomy.org/bibtex/2c2064000de3ca3013d84bfdc785a8e23/miki}, description = {[1607.03488] Radiative Transfer meets Bayesian statistics: where does your Galaxy's [CII] come from?}, interhash = {ae2f66e507256dc30b1a94d2aec359a5}, intrahash = {c2064000de3ca3013d84bfdc785a8e23}, keywords = {[CII] origin radiative transfer}, note = {cite arxiv:1607.03488Comment: 17 pages including appendices, 15 figures, 3 tables, submitted to MNRAS}, timestamp = {2016-07-14T10:53:36.000+0200}, title = {Radiative Transfer meets Bayesian statistics: where does your Galaxy's [CII] come from?}, url = {http://arxiv.org/abs/1607.03488}, year = 2016 }