Herschel extreme lensing line observations: Dynamics of two strongly lensed star-forming galaxies near redshift z = 2

James E. Rhoads, Sangeeta Malhotra, Sahar Allam, Chris Carilli, Françoise Combes, Keely Finkelstein, Steven Finkelstein, Brenda Frye, Maryvonne Gerin, Pierre Guillard, Nicole Nesvadba, Jane Rigby, Marco Spaans, Michael A. Strauss

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

We report on two regularly rotating galaxies at redshift z 2, using high-resolution spectra of the bright [C II] 158 μm emission line from the HIFI instrument on the Herschel Space Observatory. Both SDSS090122.37+181432.3 ("S0901") and SDSSJ120602.09+514229.5 ("the Clone") are strongly lensed and show the double-horned line profile that is typical of rotating gas disks. Using a parametric disk model to fit the emission line profiles, we find that S0901 has a rotation speed of vsin (i) 120 ± 7 km s-1 and a gas velocity dispersion of σ g < 23 km s -1 (1σ). The best-fitting model for the Clone is a rotationally supported disk having vsin (i) 79 ± 11 km s-1 and σ g ≲ 4 km s-1 (1σ). However, the Clone is also consistent with a family of dispersion-dominated models having σ g = 92 ± 20 km s-1. Our results showcase the potential of the [C II] line as a kinematic probe of high-redshift galaxy dynamics: [C II] is bright, accessible to heterodyne receivers with exquisite velocity resolution, and traces dense star-forming interstellar gas. Future [C II] line observations with ALMA would offer the further advantage of spatial resolution, allowing a clearer separation between rotation and velocity dispersion.

Original languageEnglish (US)
Article number8
JournalAstrophysical Journal
Volume787
Issue number1
DOIs
StatePublished - May 20 2014

Keywords

  • galaxies: evolution
  • galaxies: formation
  • galaxies: high-redshift

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Rhoads, J. E., Malhotra, S., Allam, S., Carilli, C., Combes, F., Finkelstein, K., Finkelstein, S., Frye, B., Gerin, M., Guillard, P., Nesvadba, N., Rigby, J., Spaans, M., & Strauss, M. A. (2014). Herschel extreme lensing line observations: Dynamics of two strongly lensed star-forming galaxies near redshift z = 2. Astrophysical Journal, 787(1), [8]. https://doi.org/10.1088/0004-637X/787/1/8