The SAMI Galaxy Survey: energy sources of the turbulent velocity dispersion in spatially resolved local star-forming galaxies

Creators: Zhou, Luwenjia; Federrath, Christoph; Yuan, Tiantian; Bian, Fuyan; Medling, Anne M.; Shi, Yong; Bland-Hawthorn, Joss; Bryant, Julia J.; Brough, Sarah; Catinella, Barbara; Croom, Scott M.; Goodwin, Michael; Goldstein, Gregory; Green, Andrew W.; Konstantopoulos, Iraklis S.; Lawrence, Jon S.; Owers, Matt S.; Richards, Samuel N.; Sanchez, Sebastian F.

Abstract

We investigate the energy sources of random turbulent motions of ionized gas from H α emission in eight local star-forming galaxies from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. These galaxies satisfy strict pure star-forming selection criteria to avoid contamination from active galactic nuclei (AGNs) or strong shocks/outflows. Using the relatively high spatial and spectral resolution of SAMI, we find that – on sub-kpc scales, our galaxies display a flat distribution of ionized gas velocity dispersion as a function of star formation rate (SFR) surface density. A major fraction of our SAMI galaxies shows higher velocity dispersion than predictions by feedback-driven models, especially at the low SFR surface density end. Our results suggest that additional sources beyond star formation feedback contribute to driving random motions of the interstellar medium in star-forming galaxies. We speculate that gravity, galactic shear and/or magnetorotational instability may be additional driving sources of turbulence in these galaxies.

Additional Information

© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Received: 18 March 2017. Revision Received: 13 June 2017. Accepted: 14 June 2017. Published: 20 June 2017. LZ and YS acknowledge support for this work from the National Natural Science Foundation of China (NSFC grant 11373021) and the Excellent Youth Foundation of the Jiangsu Scientific Committee (grant BK20150014). CF gratefully acknowledges funding provided by the Australian Research Council's Discovery Projects (grants DP150104329 and DP170100603). Support for AMM is provided by NASA through Hubble Fellowship grant no. HST-HF2-51377 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. for NASA, under contract NAS5-26555. We thank R. Genzel, N. Förster Schreiber, M.D. Lehnert and N.P.H. Nesvadba for their support on providing high-z measurements displayed in this work. We thank the anonymous referee for his/her thorough review and highly appreciate the comments and suggestions, which significantly contributed to improving the quality of the publication. MSO acknowledges the funding support from the Australian Research Council through a Future Fellowship (FT140100255). BC acknowledges support from the Australian Research Council's Future Fellowship (FT120100660) funding scheme. SB acknowledges the funding support from the Australian Research Council through a Future Fellowship (FT140101166). SFS thanks PAPIIT-DGAPA-IA101217 project and CONACYT-IA-180125. We would like to thank the anonymous reviewer for his/her helpful and constructive comments that greatly contributed to improving the final version of the paper. The SAMI Galaxy Survey is based on observations made at the Anglo–Australian Telescope. The Sydney-AAO Multi-object Integral field spectrograph (SAMI) was developed jointly by the University of Sydney and the Australian Astronomical Observatory. The SAMI input catalogue is based on data taken from the Sloan Digital Sky Survey, the GAMA Survey and the VST ATLAS Survey. The SAMI Galaxy Survey is funded by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and other participating institutions. The SAMI Galaxy Survey website is http://sami-survey.org/.

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