A Comparison between Nuclear Ring Star Formation in LIRGs and in Normal Galaxies with the Very Large Array

August 2021 • 2021ApJ...916...73S

Authors • Song, Y. • Linden, S. T. • Evans, A. S. • Barcos-Muñoz, L. • Privon, G. C. • Yoon, I. • Murphy, E. J. • Larson, K. L. • Díaz-Santos, T. • Armus, L. • Mazzarella, Joseph M. • Howell, J. • Inami, H. • Torres-Albà, N. • U, V. • Charmandaris, V. • McKinney, J. • Kunneriath, D. • Momjian, E.

Abstract • Nuclear rings are excellent laboratories for studying intense star formation. We present results from a study of nuclear star-forming rings in five nearby normal galaxies from the Star Formation in Radio Survey (SFRS) and four local LIRGs from the Great Observatories All-sky LIRG Survey at sub-kiloparsec resolutions using Very Large Array high-frequency radio continuum observations. We find that nuclear ring star formation (NRSF) contributes 49%-60% of the total star formation of the LIRGs, compared to 7%-40% for the normal galaxies. We characterize a total of 57 individual star-forming regions in these rings, and find that with measured sizes of 10-200 pc, NRSF regions in the LIRGs have star formation rate (SFR) and Σ_SFR up to 1.7 M_⊙ yr^-1 and 402 M_⊙ yr^-1 kpc^-2, respectively, which are about 10 times higher than in NRSF regions in the normal galaxies with similar sizes, and comparable to lensed high-z star-forming regions. At ~100-300 pc scales, we estimate low contributions (<50%) of thermal free-free emission to total radio continuum emission at 33 GHz in the NRSF regions in the LIRGs, but large variations possibly exist at smaller physical scales. Finally, using archival sub-kiloparsec resolution CO (J = 1-0) data of nuclear rings in the normal galaxies and NGC 7469 (LIRG), we find a large scatter in gas depletion times at similar molecular gas surface densities, which tentatively points to a multimodal star formation relation on sub-kiloparsec scales.

Links

• PREPRINT http://arxiv.org/abs/2107.00412
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2021ApJ...916...73S
• ELECTR https://doi.org/10.3847%2F1538-4357%2Fac05c2
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2021ApJ...916...73S
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ac05c2/pdf
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2021ApJ...916...73S