CO(1–0) imaging reveals 10-kiloparsec molecular gas reservoirs around star-forming galaxies at high redshift
Matus Rybak, J. T. Jansen, M. Frias Castillo, J. A. Hodge, P. P. van der Werf, I. Smail, G. Calistro Rivera, S. Chapman, C. -C. Chen, E. da Cunha, H. Dannerbauer, E. F. Jim’enez-Andrade, C. Lagos, C. -L. Liao, E. J. Murphy, D. Scott, A. M. Swinbank, F. Walter
arXiv:2411.06474v2 Announce Type: replace
Abstract: Massive, intensely star-forming galaxies at high redshift require a supply of molecular gas from their gas reservoirs, replenished by infall from the surrounding circumgalactic medium, to sustain their immense star-formation rates. However, our knowledge of the extent and morphology of their cold-gas reservoirs is still in its infancy.
We present the results of stacking 80 hours of JVLA observations of CO(1–0) emission — which traces the cold molecular gas — in nineteen $z=2.0-4.5$ dusty, star-forming galaxies from the AS2VLA survey. The visibility-plane stack reveals extended emission with a half-light radius of $3.8pm0.5$~kpc, 2–3$times$ more extended than the dust-obscured star formation and $1.4pm0.2times$ more extended than the stellar emission revealed by JWST. Stacking the [CI](1–0) observations for ten galaxies from our parent sample yields a half-light radius $leq$2.6~kpc, marginally smaller than CO(1–0). The CO(1–0) size is also comparable to the [CII] halos detected around high-redshift star-forming galaxies, suggesting these arise from molecular gas. Photo-dissociation region modelling indicates that the extended CO(1–0) emission arises from clumpy, dense clouds rather than smooth, diffuse gas.
Our results show that the bulk (up to 80%) of molecular gas resides outside the star-forming region; with only a small part directly contributing to their current star formation.arXiv:2411.06474v2 Announce Type: replace
Abstract: Massive, intensely star-forming galaxies at high redshift require a supply of molecular gas from their gas reservoirs, replenished by infall from the surrounding circumgalactic medium, to sustain their immense star-formation rates. However, our knowledge of the extent and morphology of their cold-gas reservoirs is still in its infancy.
We present the results of stacking 80 hours of JVLA observations of CO(1–0) emission — which traces the cold molecular gas — in nineteen $z=2.0-4.5$ dusty, star-forming galaxies from the AS2VLA survey. The visibility-plane stack reveals extended emission with a half-light radius of $3.8pm0.5$~kpc, 2–3$times$ more extended than the dust-obscured star formation and $1.4pm0.2times$ more extended than the stellar emission revealed by JWST. Stacking the [CI](1–0) observations for ten galaxies from our parent sample yields a half-light radius $leq$2.6~kpc, marginally smaller than CO(1–0). The CO(1–0) size is also comparable to the [CII] halos detected around high-redshift star-forming galaxies, suggesting these arise from molecular gas. Photo-dissociation region modelling indicates that the extended CO(1–0) emission arises from clumpy, dense clouds rather than smooth, diffuse gas.
Our results show that the bulk (up to 80%) of molecular gas resides outside the star-forming region; with only a small part directly contributing to their current star formation.