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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 molecular gas content of seven high-redshift (z ~ 1.6) starburst galaxies with the Atacama Large (sub-)Millimeter Array and IRAM/Plateau de Bure Interferometer. Our targets are selected from the sample of Herschel far-infrared detected galaxies having star formation rates (~300-800 Msolar/yr) elevated (>4x) above the star-forming `main sequence, and included in the FMOS-COSMOS near-infrared spectroscopic survey of star-forming galaxies at z ~ 1.6 with Subaru. We detect CO emission in all cases at high levels of significance, indicative of high gas fractions (~30-50%). Even more compelling, we firmly establish with a clean and systematic selection that starbursts, identified as main-sequence outliers, at high redshift generally have a lower ratio of CO to total infrared luminosity as compared to typical main-sequence star-forming galaxies, although with a smaller offset 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. Along with a heightened star formation efficiency, 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 interstellar medium.
We compare various star formation rate (SFR) indicators for star-forming galaxies at $1.4<z<2.5$ in the COSMOS field. The main focus is on the SFRs from the far-IR (PACS-Herschel data) with those from the ultraviolet, for galaxies selected according
We present the detection of CO(5-4) with S/N> 7 - 13 and a lower CO transition with S/N > 3 (CO(4-3) for 4 galaxies, and CO(3-2) for one) with ALMA in band 3 and 4 in five main sequence star-forming galaxies with stellar masses 3-6x10^10 M/M_sun at 3
The origin of the star forming main sequence ( i.e., the relation between star formation rate and stellar mass, globally or on kpc-scales; hereafter SFMS) remains a hotly debated topic in galaxy evolution. Using the ALMA-MaNGA QUEnching and STar form
Star formation rate (SFR) measurements at z>4 have relied mostly on rest-frame far-ultraviolet (FUV) observations. The corrections for dust attenuation based on IRX-$beta$ relation are highly uncertain and are still debated in the literature. Hence,
Deep far-infrared (FIR) cosmological surveys are known to be affected by source confusion, causing issues when examining the main sequence (MS) of star forming galaxies. This has typically been partially tackled by the use of stacking. However, stack