We report the detection of CO ( J =1 \to 0 ) emission in the strongly lensed high-redshift quasars IRAS F10214+4724 ( z =2.286 ) , the Cloverleaf ( z =2.558 ) , RX J0911+0551 ( z =2.796 ) , SMM J04135+10277 ( z =2.846 ) , and MG 0751+2716 ( z =3.200 ) , using the Expanded Very Large Array and the Green Bank Telescope .
We report lensing-corrected CO ( J =1 \to 0 ) line luminosities of L ^ { \prime } _ { CO } = 0.34 - 18.4 \times 10 ^ { 10 } K km s ^ { -1 } pc ^ { 2 } and total molecular gas masses of M ( { H _ { 2 } } ) = 0.27 - 14.7 \times 10 ^ { 10 } M _ { \odot } for the sources in our sample .
Based on CO line ratios relative to previously reported observations in J \geq 3 rotational transitions and line excitation modeling , we find that the CO ( J =1 \to 0 ) line strengths in our targets are consistent with single , highly-excited gas components with constant brightness temperature up to mid- J levels .
We thus do not find any evidence for luminous extended , low excitation , low surface brightness molecular gas components .
These properties are comparable to those found in z > 4 quasars with existing CO ( J =1 \to 0 ) observations .
These findings stand in contrast to recent CO ( J =1 \to 0 ) observations of z \simeq 2–4 submillimeter galaxies ( SMGs ) , which have lower CO excitation and show evidence for multiple excitation components , including some low-excitation gas .
These findings are consistent with the picture that gas-rich quasars and SMGs represent different stages in the early evolution of massive galaxies .