%0 Generic %1 silverman2015higher %A Silverman, J. D. %A Daddi, E. %A Rodighiero, G. %A Rujopakarn, W. %A Sargent, M. %A Renzini, A. %A Liu, D. %A Feruglio, C. %A Kashino, D. %A Sanders, D. %A Kartaltepe, J. %A Nagao, T. %A Arimoto, N. %A Berta, S. %A Bethermin, M. %A Lutz, D. %A Magdis, G. %A Mancini, C. %A Onodera, M. %A Zamorani, G. %D 2015 %K co efficiency gas high-z stars %T A higher efficiency of converting gas to stars push galaxies at z ~ 1.6 well above the star-forming main sequence %U http://arxiv.org/abs/1505.04977 %X Local starbursts have a higher efficiency of converting gas into stars, as compared to typical star-forming galaxies at a given stellar mass, possibly indicative of different modes of star formation. With the peak epoch of galaxy formation occurring at z > 1, it remains to be established whether such an efficient mode of star formation is occurring at high-redshift. To address this issue, we measure the CO molecular gas content of seven high-redshift starburst galaxies with ALMA and IRAM/PdBI. Our sample is selected from the FMOS-COSMOS near-infrared spectroscopic survey of star-forming galaxies at z ~ 1.6 with Subaru. All galaxies have star formation rates (~300-800 Msolar/yr) elevated, by at least four times, above the star-forming main sequence. We detect CO emission in all cases at high significance, indicative of plentiful gas supplies (f_gas ~ 30-50%). Even more compelling, we firmly establish for the first time that starbursts at high redshift systematically have a lower ratio of CO to total infrared luminosity as compared to typical 'main-sequence' star-forming galaxies, although with an offset less than expected based on past studies of local starbursts. We put forward a hypothesis that there exists a continuous increase in star formation efficiency with elevation from the main sequence with galaxy mergers as a possible physical driver. In support of this scenario, our high-redshift sample is similar in other respects to local starbursts such as being metal rich and having a higher ionization state of the ISM.

@misc{silverman2015higher, abstract = {Local starbursts have a higher efficiency of converting gas into stars, as compared to typical star-forming galaxies at a given stellar mass, possibly indicative of different modes of star formation. With the peak epoch of galaxy formation occurring at z > 1, it remains to be established whether such an efficient mode of star formation is occurring at high-redshift. To address this issue, we measure the CO molecular gas content of seven high-redshift starburst galaxies with ALMA and IRAM/PdBI. Our sample is selected from the FMOS-COSMOS near-infrared spectroscopic survey of star-forming galaxies at z ~ 1.6 with Subaru. All galaxies have star formation rates (~300-800 Msolar/yr) elevated, by at least four times, above the star-forming main sequence. We detect CO emission in all cases at high significance, indicative of plentiful gas supplies (f_gas ~ 30-50%). Even more compelling, we firmly establish for the first time that starbursts at high redshift systematically have a lower ratio of CO to total infrared luminosity as compared to typical 'main-sequence' star-forming galaxies, although with an offset less than expected based on past studies of local starbursts. We put forward a hypothesis that there exists a continuous increase in star formation efficiency with elevation from the main sequence with galaxy mergers as a possible physical driver. In support of this scenario, our high-redshift sample is similar in other respects to local starbursts such as being metal rich and having a higher ionization state of the ISM.}, added-at = {2015-05-20T09:41:38.000+0200}, author = {Silverman, J. D. and Daddi, E. and Rodighiero, G. and Rujopakarn, W. and Sargent, M. and Renzini, A. and Liu, D. and Feruglio, C. and Kashino, D. and Sanders, D. and Kartaltepe, J. and Nagao, T. and Arimoto, N. and Berta, S. and Bethermin, M. and Lutz, D. and Magdis, G. and Mancini, C. and Onodera, M. and Zamorani, G.}, biburl = {https://www.bibsonomy.org/bibtex/287b69fa69638a388714def3efb037eee/miki}, description = {[1505.04977] A higher efficiency of converting gas to stars push galaxies at z ~ 1.6 well above the star-forming main sequence}, interhash = {e1dd356ea768cfde014117957d0f25ba}, intrahash = {87b69fa69638a388714def3efb037eee}, keywords = {co efficiency gas high-z stars}, note = {cite arxiv:1505.04977Comment: Submitted to ApJ Letters; 6 pages, 4 figures}, timestamp = {2015-05-20T09:41:38.000+0200}, title = {A higher efficiency of converting gas to stars push galaxies at z ~ 1.6 well above the star-forming main sequence}, url = {http://arxiv.org/abs/1505.04977}, year = 2015 }