B. H. C. Emonts,
I. Feain,
M. Y. Mao,
R. P. Norris,
G. Miley,
R. D. Ekers,
M. Villar-Martín,
H. J. A. Röttgering,
E. M. Sadler, G. Rees,
R. Morganti,
D. J. Saikia,
T. A. Oosterloo,
J. B. Stevens,
and C. N. Tadhunter
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ABSTRACT: We report the detection of molecular CO(1-0) gas in the high-z radio galaxy MRC 0152-209 (z = 1.92) with the Australia Telescope Compact Array Broadband Backend (ATCA/CABB). This is the third known detection of CO(1-0) in a high-z radio galaxy to date. CO(1-0) is the most robust tracer of the overall molecular gas content (including the widespread, low-density, and sub-thermally excited component), hence observations of CO(1-0) are crucial for studying galaxy evolution in the early universe. We derive L'CO = 6.6 ± 2.0 × 1010 K km s–1 pc2 for MRC 0152-209, which is comparable to that derived from CO(1-0) observations of several high-z submillimeter and star-forming BzK galaxies. The CO(1-0) traces a total molecular hydrogen mass of = 5 × 1010 (αx/0.8) M ☉. MRC 0152-209 is an infrared bright radio galaxy, in which a large reservoir of cold molecular gas has not (yet) been depleted by star formation or radio source feedback. Its compact radio source is reliably detected at 40 GHz and has a steep spectral index of α = –1.3 between 1.4 and 40 GHz (4-115 GHz in the galaxy's rest frame). MRC 0152-209 is part of an ongoing systematic ATCA/CABB survey of CO(1-0) in high-z radio galaxies between 1.7 < z < 3.
The Astrophysical Journal Letters 05/2011; 734(1):L25. · 5.53 Impact Factor