Measurements of CO redshifts with Z-Spec for lensed submillimeter galaxies discovered in the H-ATLAS survey

Lupu, R. E., Scott, K. S., Aguirre, J. E., Aretxaga, I., Auld, Robbie Richard, Barton, E., Beelen, A., Bertoldi, F., Bock, J. J., Bonfield, D., Bradford, C. M., Buttigilione, S., Cava, A., Clements, D. L., Cooke, J., Cooray, A., Dannerbauer, H., Dariush, A., De Zotti, G., Dunne, Loretta ORCID: https://orcid.org/0000-0001-9880-2543, Dye, S., Eales, Stephen Anthony ORCID: https://orcid.org/0000-0002-7394-426X, Frayer, D., Fritz, J., Glenn, J., Hughes, D. H., Ibar, E., Ivison, R. J., Jarvis, M. J., Kamenetzky, J., Kim, S., Lagache, G., Leeuw, L., Maddox, Steve ORCID: https://orcid.org/0000-0001-5549-195X, Maloney, P. R., Matsuhara, H., Murphy, E. J., Naylor, B. J., Negrello, M., Nguien, H., Omont, A., Pascale, Enzo ORCID: https://orcid.org/0000-0002-3242-8154, Pohlen, Michael, Rigby, E., Rodighiero, G., Serjeant, S., Smith, D., Temi, P., Thompson, M., Valtchanov, I., Verma, A., Vieira, J. D. and Zmuidzinas, J. 2012. Measurements of CO redshifts with Z-Spec for lensed submillimeter galaxies discovered in the H-ATLAS survey. Astrophysical Journal 757 (2) , 135. 10.1088/0004-637X/757/2/135

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Abstract

We present new observations from Z-Spec, a broadband 185 - 305 GHz spectrometer, of sub-millimeter bright lensed sources recently detected by the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). Four out of five sources observed were detected in CO, and their redshifts measured using a new redshift finding algorithm that uses combinations of the signal-to-noise of all the lines falling in the Z-Spec bandpass to determine redshifts with high confidence, even in cases where the signal-to-noise in individual lines is low. Lower limits for the dust masses (~a few 10^8 M_sun) and spatial extents (~1 kpc equivalent radius) are derived from the continuum spectral energy distributions, corresponding to dust temperatures between 54 and 69 K. The dust and gas properties, as determined by the CO line luminosities, are characteristic of dusty starburst galaxies, with star formation rates of 10^2-10^3 M_sun/yr. In the LTE approximation, we derive relatively low CO excitation temperature(<100 K) and optical depths (tau < 1). Using a maximum likelihood technique, we perform a non-LTE excitation analysis of the detected CO lines in each galaxy to further constrain the bulk molecular gas properties. We find that the mid-J CO lines measured by Z-Spec localize the best solutions to either a high-temperature / low-density region, or a low-temperature / high-density region near the LTE solution, with the optical depth varying accordingly.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Uncontrolled Keywords:	galaxies; distances and redshifts – galaxies; high-redshift – galaxies; ISM– line; identification – submillimeter: galaxies
Publisher:	American Astronomical Society
ISSN:	0004-637X
Last Modified:	21 Oct 2022 09:15
URI:	https://orca.cardiff.ac.uk/id/eprint/35769

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