We present CI(2-1) and multi-transition (CO)-C-12 observations of a dusty star-forming galaxy, ACT J2029+0120, which we spectroscopically confirm to lie at z = 2.64. We detect CO(3-2), CO(5-4), CO(7-6), CO(8-7), and CI (2-1) at high significance, tentatively detect HCO+(4-3), and place strong upper limits on the integrated strength of dense gas tracers (HCN(4-3) and CS(7-6)). Multi-transition CO observations and dense gas tracers can provide valuable constraints on the molecular gas content and excitation conditions in high-redshift galaxies. We therefore use this unique data set to construct a CO spectral line energy distribution (SLED) of the source, which is most consistent with that of a ULIRG/Seyfert or QSO host object in the taxonomy of the Herschel Comprehensive ULIRG Emission Survey. We employ RADEX models to fit the peak of the CO SLED, inferring a temperature of T similar to 117 K and n(H2) similar to 10(5) cm(-3), most consistent with a ULIRG/QSO object and the presence of high-density tracers. We also find that the velocity width of the C I line is potentially larger than seen in all CO transitions for this object, and that the L'(Ci(2-1))/L'(CO(3-2)) ratio is also larger than seen in other lensed and unlensed submillimeter galaxies and QSO hosts; if confirmed, this anomaly could be an effect of differential lensing of a shocked molecular outflow.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/625330 |
| Date | 27 July 2017 |
| Creators | Roberts-Borsani, G. W., Jiménez-Donaire, M. J., Daprà, M., Alatalo, K., Aretxaga, I., Álvarez-Márquez, J., Baker, A. J., Fujimoto, S., Gallardo, P. A., Gralla, M., Hilton, M., Hughes, J. P., Jiménez, C., Laporte, N., Marriage, T. A., Nati, F., Rivera, J., Sievers, A., Weiß, A., Wilson, G. W., Wollack, E. J., Yun, M. S. |
| Contributors | Univ Arizona, Steward Observ |
| Publisher | IOP PUBLISHING LTD |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017. The American Astronomical Society. All rights reserved. |
| Relation | http://stacks.iop.org/0004-637X/844/i=2/a=110?key=crossref.9737ee98771943a85988d4e47015b8b5 |
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