%0 Generic %1 tan2013search %A Tan, Qinghua %A Daddi, Emanuele %A Sargent, Mark T. %A Magdis, Georgios %A Hodge, Jacqueline A. %A Bethermin, Matthieu %A Bournaud, Frederic %A Carilli, Chris L. %A Dannerbauer, Helmut %A Dickinson, Mark %A Elbaz, David %A Gao, Yu %A Morrison, Glenn E. %A Owen, Frazer N. %A Pannella, Maurilio %A Riechers, Dominik A. %A Walter, Fabian %D 2013 %K gas high-z lbgs molecular %T A deep search for molecular gas in two massive Lyman break galaxies at z=3 and 4: vanishing CO-emission due to low metallicity? %U http://arxiv.org/abs/1309.5448 %X We present deep IRAM Plateau de Bure Interferometer (PdBI) observations, searching for CO-emission toward two massive, non-lensed Lyman break galaxies (LBGs) at z=3.216 and 4.058. With one low significance CO detection (3.5 sigma) and one sensitive upper limit, we find that the CO lines are >~ 3-4 times weaker than expected based on the relation between IR and CO luminosities followed by similarly, massive galaxies at z=0-2.5. This is consistent with a scenario in which these galaxies have low metallicity, causing an increased CO-to-H_2 conversion factor, i.e., weaker CO-emission for a given molecular (H_2) mass. The required metallicities at z>3 are lower than predicted by the fundamental metallicity relation (FMR) at these redshifts, consistent with independent evidence. Unless our galaxies are atypical in this respect, detecting molecular gas in normal galaxies at z>3 may thus remain challenging even with ALMA.

@misc{tan2013search, abstract = {We present deep IRAM Plateau de Bure Interferometer (PdBI) observations, searching for CO-emission toward two massive, non-lensed Lyman break galaxies (LBGs) at z=3.216 and 4.058. With one low significance CO detection (3.5 sigma) and one sensitive upper limit, we find that the CO lines are >~ 3-4 times weaker than expected based on the relation between IR and CO luminosities followed by similarly, massive galaxies at z=0-2.5. This is consistent with a scenario in which these galaxies have low metallicity, causing an increased CO-to-H_2 conversion factor, i.e., weaker CO-emission for a given molecular (H_2) mass. The required metallicities at z>3 are lower than predicted by the fundamental metallicity relation (FMR) at these redshifts, consistent with independent evidence. Unless our galaxies are atypical in this respect, detecting molecular gas in normal galaxies at z>3 may thus remain challenging even with ALMA.}, added-at = {2013-09-24T17:30:25.000+0200}, author = {Tan, Qinghua and Daddi, Emanuele and Sargent, Mark T. and Magdis, Georgios and Hodge, Jacqueline A. and Bethermin, Matthieu and Bournaud, Frederic and Carilli, Chris L. and Dannerbauer, Helmut and Dickinson, Mark and Elbaz, David and Gao, Yu and Morrison, Glenn E. and Owen, Frazer N. and Pannella, Maurilio and Riechers, Dominik A. and Walter, Fabian}, biburl = {https://www.bibsonomy.org/bibtex/2be7f82df095dcaf62a99611a7a0f626f/miki}, description = {[1309.5448] A deep search for molecular gas in two massive Lyman break galaxies at z=3 and 4: vanishing CO-emission due to low metallicity?}, interhash = {eed2436693067a4652950e7314e672d4}, intrahash = {be7f82df095dcaf62a99611a7a0f626f}, keywords = {gas high-z lbgs molecular}, note = {cite arxiv:1309.5448Comment: 9 pages, 3 figures, accepted for publication in Astrophysical Journal Letters}, timestamp = {2013-09-24T17:30:25.000+0200}, title = {A deep search for molecular gas in two massive Lyman break galaxies at z=3 and 4: vanishing CO-emission due to low metallicity?}, url = {http://arxiv.org/abs/1309.5448}, year = 2013 }