Abstract
At the highest stellar masses (log(M∗) ≳ 11.5 Mo), only a small fraction of galaxies are disk-like and actively star-forming objects. These so-called 'super spirals' are ideal objects to better understand how galaxy evolution proceeds and to extend our knowledge about the relation between stars and gas to a higher stellar mass regime. We present new CO(1-0) data for a sample of 46 super spirals and for 18 slightly lower-mass (log(M∗) > 11.0 Mo) galaxies with broad HI lines - HI fast-rotators (HI-FRs). We analyze their molecular gas mass, derived from CO(1-0), in relation to their star formation rate (SFR) and stellar mass, and compare the results to values and scaling relations derived from lower-mass galaxies. We confirm that super spirals follow the same star-forming main sequence (SFMS) as lower-mass galaxies. We find that they possess abundant molecular gas (mean redshift-corrected molecular gas mass fraction (log(fmol,zcorr) = -1.36 ± 0.02), which lies above the extrapolation of the scaling relation with stellar mass derived from lower-mass galaxies, but within the relation between fmol and the distance to the SFMS. The molecular gas depletion time, τdep = Mmol/SFR, is higher than for lower-mass galaxies on the SFMS (τdep = 9.30 ± 0.03, compared to τdep = 9.00 ± 0.02 for the comparison sample) and seems to continue an increasing trend with stellar mass. HI-FR galaxies have an atomic-to-molecular gas mass ratio that is in agreement with that of lower-mass galaxies, indicating that the conversion from the atomic to molecular gas proceeds in a similar way. We conclude that the availability of molecular gas is a crucial factor to enable star formation to continue and that, if gas is present, quenching is not a necessary destiny for high-mass galaxies. The difference in gas depletion time suggests that the properties of the molecular gas at high stellar masses are less favorable for star formation.
Original language | English |
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Article number | A87 |
Journal | Astronomy and Astrophysics |
Volume | 673 |
Early online date | 10 May 2023 |
DOIs | |
Publication status | Published - 31 May 2023 |
Bibliographical note
Funding Information:We thank the referee for the careful revision of the manuscript and constructive comments. UL acknowledges support by the research projects AYA2017-84897-P and PID2020-114414GB-I00 from the Spanish Ministerio de Economía y Competitividad, from the European Regional Development Funds (FEDER) and the Junta de Andalucía (Spain) grants FQM108. This work is based on observations carried out under project numbers 205-19 and 068-20 with the IRAM 30m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). This research made use of the “K-corrections calculator” service available at http://kcor.sai.msu.ru/ . This research made use of Astropy, a community- developed core Python ( http://www.python.org ) package for Astronomy (Astropy Collaboration 2013, 2018); ipython (Pérez & Granger 2007); matplotlib (Hunter 2007); SciPy, a collection of open source software for scientific computing in Python (Virtanen et al. 2020); and NumPy, a structure for efficient numerical computation (van der Walt et al. 2011). This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This work was made possible by the NASA/IPAC Extragalactic Database and the NASA/ IPAC Infrared Science Archive, which are both operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We acknowledge the usage of the HyperLeda database ( http://leda.univ-lyon1.fr ).
Keywords
- Galaxies: evolution
- Galaxies: ISM
- Galaxies: spiral
- ISM: molecules
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science