%0 Generic %1 vallini2015ciisfr %A Vallini, L. %A Gallerani, S. %A Ferrara, A. %A Pallottini, A. %A Yue, B. %D 2015 %K alma cii high redshift relation sfr %T On the CII-SFR relation in high redshift galaxies %U http://arxiv.org/abs/1507.00340 %X After two ALMA observing cycles, only a handful of CII $158\,m$ emission line searches in z>6 galaxies have reported a positive detection, questioning the applicability of the local CII-SFR relation to high-z systems. To investigate this issue we use the Vallini et al. 2013 (V13) model, based on high-resolution, radiative transfer cosmological simulations to predict the CII emission from the interstellar medium of a z~7 (halo mass $M_h=1.17\times10^11M_ødot$) galaxy. We improve the V13 model by including (a) a physically-motivated metallicity (Z) distribution of the gas, (b) the contribution of Photo-Dissociation Regions (PDRs), (c) the effects of Cosmic Microwave Background on the CII line luminosity. We study the relative contribution of diffuse neutral gas to the total CII emission ($F _diff/F_tot$) for different SFR and Z values. We find that the CII emission arises predominantly from PDRs: regardless of the galaxy properties, $F _diff/F_tot10$% since, at these early epochs, the CMB temperature approaches the spin temperature of the CII transition in the cold neutral medium ($T_CMBT_s^CNM20$ K). Our model predicts a high-z CII-SFR relation consistent with observations of local dwarf galaxies ($0.02<Z/Z_ødot<0.5$). The CII deficit suggested by actual data ($L_CII<2.010^7 L_ødot$ in BDF3299 at z~7.1) if confirmed by deeper ALMA observations, can be ascribed to negative stellar feedback disrupting molecular clouds around star formation sites. The deviation from the local CII-SFR would then imply a modified Kennicutt-Schmidt relation in z>6 galaxies. Alternatively/in addition, the deficit might be explained by low gas metallicities ($Z<0.1 Z_ødot$).

@misc{vallini2015ciisfr, abstract = {After two ALMA observing cycles, only a handful of [CII] $158\,\mu m$ emission line searches in z>6 galaxies have reported a positive detection, questioning the applicability of the local [CII]-SFR relation to high-z systems. To investigate this issue we use the Vallini et al. 2013 (V13) model, based on high-resolution, radiative transfer cosmological simulations to predict the [CII] emission from the interstellar medium of a z~7 (halo mass $M_h=1.17\times10^{11}M_{\odot}$) galaxy. We improve the V13 model by including (a) a physically-motivated metallicity (Z) distribution of the gas, (b) the contribution of Photo-Dissociation Regions (PDRs), (c) the effects of Cosmic Microwave Background on the [CII] line luminosity. We study the relative contribution of diffuse neutral gas to the total [CII] emission ($F _{diff}/F_{tot}$) for different SFR and Z values. We find that the [CII] emission arises predominantly from PDRs: regardless of the galaxy properties, $F _{diff}/F_{tot}\leq 10$% since, at these early epochs, the CMB temperature approaches the spin temperature of the [CII] transition in the cold neutral medium ($T_{CMB}\sim T_s^{CNM}\sim 20$ K). Our model predicts a high-z [CII]-SFR relation consistent with observations of local dwarf galaxies ($0.02<Z/Z_{\odot}<0.5$). The [CII] deficit suggested by actual data ($L_{CII}<2.0\times 10^7 L_{\odot}$ in BDF3299 at z~7.1) if confirmed by deeper ALMA observations, can be ascribed to negative stellar feedback disrupting molecular clouds around star formation sites. The deviation from the local [CII]-SFR would then imply a modified Kennicutt-Schmidt relation in z>6 galaxies. Alternatively/in addition, the deficit might be explained by low gas metallicities ($Z<0.1 Z_{\odot}$).}, added-at = {2015-07-03T09:52:20.000+0200}, author = {Vallini, L. and Gallerani, S. and Ferrara, A. and Pallottini, A. and Yue, B.}, biburl = {https://www.bibsonomy.org/bibtex/2b6a81f3fa63bdbb454a3a42a2e9fb8ac/miki}, description = {[1507.00340] On the [CII]-SFR relation in high redshift galaxies}, interhash = {ca652db4084f4a27eec65433a9e0f1bc}, intrahash = {b6a81f3fa63bdbb454a3a42a2e9fb8ac}, keywords = {alma cii high redshift relation sfr}, note = {cite arxiv:1507.00340Comment: 7 pages, 5 figures}, timestamp = {2015-07-03T09:52:20.000+0200}, title = {On the [CII]-SFR relation in high redshift galaxies}, url = {http://arxiv.org/abs/1507.00340}, year = 2015 }