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arXiv · 0903.0862

CO line emission in the halo of a radio galaxy at z=2.6

N. P. H. Nesvadba·R. Neri·C. De Breuck·M. D. Lehnert·D. Downes·F. Walter·A. Omont·F. Boulanger·N. Seymour
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Abstract

We report the detection of luminous CO(3-2) line emission in the halo of the z=2.6 radio galaxy (HzRG) TXS0828+193, which has no detected counterpart at optical to mid-infrared wavelengths implying a stellar mass < few x10^9 M_sun and relatively low star-formation rates. With the IRAM PdBI we find two CO emission line components at the same position at ~80 kpc distance from the HzRG along the axis of the radio jet, with different blueshifts of few 100 km s^-1 relative to the HzRG and a total luminosity of ~2x10^10 K km s^-1 pc^2 detected at 8 sigma significance. HzRGs have significant galaxy overdensities and extended halos of metal-enriched gas often with embedded clouds or filaments of denser material, and likely trace very massive dark-matter halos. The CO emission may be associated with a gas-rich, low-mass satellite galaxy with little on-going star formation, in contrast to all previous CO detections of galaxies at similar redshifts. Alternatively, the CO may be related to a gas cloud or filament and perhaps jet-induced gas cooling in the outer halo, somewhat in analogy with extended CO emission found in low-redshift galaxy clusters.

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N. P. H. Nesvadba, R. Neri, C. De Breuck, M. D. Lehnert, D. Downes, F. Walter, A. Omont, F. Boulanger, N. Seymour. 2009-03-04. CO line emission in the halo of a radio galaxy at z=2.6. https://doi.org/10.1111/j.1745-3933.2009.00631.x

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