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arXiv · 1404.7143

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·Francoise Combes·Keely Finkelstein·Steven Finkelstein·Brenda Frye·Maryvonne Gerin·Pierre Guillard·Nicole Nesvadba·Jane Rigby·Marco Spaans·Michael A. Strauss
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Abstract

We report on two regularly rotating galaxies at redshift z=2, using high resolution spectra of the bright [CII] 158 micron emission line from the HIFI instrument on the Herschel Space Observatory. Both SDSS090122.37+181432.3 ("S0901") and SDSS J120602.09+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 v sin(i) = 120 +/- 7 km/s and gas velocity dispersion sigma < 23 km/s. The best fitting model for the Clone is a rotationally supported disk having v sin(i) = 79 +/- 11 km/s and sigma < 4km/s. However the Clone is also consistent with a family of dispersion-dominated models having sigma = 92 +/- 20 km/s. Our results showcase the potential of the [CII] line as a kinematic probe of high redshift galaxy dynamics: [CII] is bright; accessible to heterodyne receivers with exquisite velocity resolution; and traces dense star-forming interstellar gas. Future [CII] line observations with ALMA would offer the further advantage of spatial resolution, allowing a clearer separation between rotation and velocity dispersion.

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James E. Rhoads, Sangeeta Malhotra, Sahar Allam, Chris Carilli, Francoise Combes, Keely Finkelstein, Steven Finkelstein, Brenda Frye, Maryvonne Gerin, Pierre Guillard, Nicole Nesvadba, Jane Rigby, Marco Spaans, Michael A. Strauss. 2014-04-28. Herschel Extreme Lensing Line Observations: Dynamics of two strongly lensed star forming galaxies near redshift z = 2. https://doi.org/10.1088/0004-637x/787/1/8

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