• DOI:10.3847/1538-4357/aa7fef
• Corpus ID: 119017774

Cloud-scale ISM Structure and Star Formation in M51

@article{Leroy2017CloudscaleIS,
  title={Cloud-scale ISM Structure and Star Formation in M51},
  author={Adam K. Leroy and Eva Schinnerer and Annie Hughes and J. M. Diederik Kruijssen and Sharon E. Meidt and Andreas Schruba and Jiayi Sun and Frank Bigiel and G. Aniano and Guillermo A. Blanc and Alberto D. Bolatto and M{\'e}lanie Chevance and D. Colombo and Molly Gallagher and Santiago Garc{\'i}a-Burillo and Carsten Kramer and Miguel Querejeta and J{\'e}r{\^o}me Pety and Todd A. Thompson and Antonio Usero},
  journal={The Astrophysical Journal},
  year={2017},
  volume={846}
}

• A. Leroy, E. Schinnerer, +17 authors A. Usero
• Published 26 June 2017
• Physics
• The Astrophysical Journal

We compare the structure of molecular gas at 40 pc resolution to the ability of gas to form stars across the disk of the spiral galaxy M51. We break the PAWS survey into 370 pc and 1.1 kpc resolution elements, and within each we estimate the molecular gas depletion time ( ), the star-formation efficiency per free-fall time ( ), and the mass-weighted cloud-scale (40 pc) properties of the molecular gas: surface density, Σ, line width, σ, and , a parameter that traces the boundedness of the gas. We show that the cloud-scale surface density appears to be a reasonable proxy for mean volume density. Applying this, we find a typical star-formation efficiency per free-fall time, , lower than adopted in many models and found for local clouds. Furthermore, the efficiency per free-fall time anti-correlates with both Σ and σ, in some tension with turbulent star-formation models. The best predictor of the rate of star formation per unit gas mass in our analysis is , tracing the strength of self-gravity, with . The sense of the correlation is that gas with stronger self-gravity (higher b) forms stars at a higher rate (low ). The different regions of the galaxy mostly overlap in as a function of b, so that low b explains the surprisingly high found toward the inner spiral arms found by Meidt et al. ().