KINEMATIC CLASSIFICATIONS OF LOCAL INTERACTING GALAXIES: IMPLICATIONS FOR THE MERGER/DISK CLASSIFICATIONS AT HIGH-z

Journal Article · Mon Apr 20 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/803/2/62· OSTI ID:22525406

Hung, Chao-Ling; Larson, Kirsten L.; Sanders, D. B. ^[1]; Rich, Jeffrey A. ^[2]; Yuan, Tiantian; Kewley, Lisa J. ^[3]; Casey, Caitlin M. ^[4]; Smith, Howard A. ^[5]

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1. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
2. Infrared Processing and Analysis Center, Caltech 100-22, Pasadena, CA 91125 (United States)
3. Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd., Weston ACT 2611 (Australia)
4. Department of Physics and Astronomy, University of California at Irvine, 2162 Frederick Reines Hall, Irvine, CA 92697 (United States)
5. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

The classification of galaxy mergers and isolated disks is key for understanding the relative importance of galaxy interactions and secular evolution during the assembly of galaxies. Galaxy kinematics as traced by emission lines have been used to suggest the existence of a significant population of high-z star-forming galaxies consistent with isolated rotating disks. However, recent studies have cautioned that post-coalescence mergers may also display disk-like kinematics. To further investigate the robustness of merger/disk classifications based on kinematic properties, we carry out a systematic classification of 24 local (U)LIRGs spanning a range of morphologies: from isolated spiral galaxies, ongoing interacting systems, to fully merged remnants. We artificially redshift the Wide Field Spectrograph observations of these local (U)LIRGs to z = 1.5 to make a realistic comparison with observations at high-z, and also to ensure that all galaxies have the same spatial sampling of ∼900 pc. Using both kinemetry-based and visual classifications, we find that the reliability of kinematic classification shows a strong trend with the interaction stage of galaxies. Mergers with two nuclei and tidal tails have the most distinct kinematics compared to isolated disks, whereas a significant population of the interacting disks and merger remnants are indistinguishable from isolated disks. The high fraction of mergers displaying disk-like kinematics reflects the complexity of the dynamics during galaxy interactions. Additional merger indicators such as morphological properties traced by stars or molecular gas are required to further constrain the merger/disk classifications at high-z.

• OSTI ID: 22525406
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 803; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CLASSIFICATION
COALESCENCE
COMPARATIVE EVALUATIONS
EMISSION SPECTRA
GALACTIC EVOLUTION
GALAXIES
INDICATORS
MORPHOLOGY
RED SHIFT
RELIABILITY
STAR EVOLUTION
STARS