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Published July 20, 2008 | Version Published
Journal Article Open

Kinemetry of SINS high-redshift star-forming galaxies : distinguishing rotating disks from major mergers

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Abstract

We present a simple set of kinematic criteria that can distinguish between galaxies dominated by ordered rotational motion and those involved in major merger events. Our criteria are based on the dynamics of the warm ionized gas (as traced by Hα) within galaxies, making this analysis accessible to high-redshift systems, whose kinematics are primarily traceable through emission features. Using the method of kinemetry (developed by Krajnović and coworkers), we quantify asymmetries in both the velocity and velocity dispersion maps of the warm gas, and the resulting criteria enable us to empirically differentiate between nonmerging and merging systems at high redshift. We apply these criteria to 11 of our best-studied rest-frame UV/optical-selected z ~ 2 galaxies for which we have near-infrared integral-field spectroscopic data from SINFONI on the VLT. Of these 11 systems, we find that >50% have kinematics consistent with a single rotating disk interpretation, while the remaining systems are more likely undergoing major mergers. This result, combined with the short formation timescales of these systems, provides evidence that rapid, smooth accretion of gas plays a significant role in galaxy formation at high redshift.

Additional Information

© 2008 The American Astronomical Society. Received 2007 November 16; accepted 2008 February 5. We are very grateful to the entire SINS team, whose input greatly improved the quality of this work. We also thank Carl Heiles for many useful discussions and the anonymous referee for helpful comments. N. M. F. S. acknowledges support by the Schwerpunkt Programm SPP1177 of the Deutsche Forschungsgemeinschaft. N. A. acknowledges support from a Grant-in-Aid for Scientific Research (19540245) by the Japanese Ministry of Education, Culture, Sports, and Science. S. A. and L. C. have been supported by the Spanish Ministry for Education and Science under grants PNE2005-01480 and ESP2007-65475-C02-01.

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Additional details

Identifiers

Eprint ID
14095
Resolver ID
CaltechAUTHORS:20090428-075610786

Funding

Deutsche Forschungsgemeinschaft (DFG)
Schwerpunkt Programm SPP1177
Ministry of Education, Culture, Sports, Science, and Technology (MEXT)
19540245
Ministerio de Educación y Ciencia (MEC)
PNE2005-01480
Ministerio de Educación y Ciencia (MEC)
ESP2007-65475-C02-01

Dates

Created
2009-08-07
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Updated
2021-11-08
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