2020MNRAS.496L.127G -
Mon. Not. R. Astron. Soc., 496, L127-L132 (2020/July-3)
The universal acceleration scale from stellar feedback.
GRUDIC M.Y., BOYLAN-KOLCHIN M., FAUCHER-GIGUERE C.-A. and HOPKINS P.F.
Abstract (from CDS):
It has been established for decades that rotation curves deviate from the Newtonian gravity expectation given baryons alone below a characteristic acceleration scale g†∼10–8 cm s–2, a scale promoted to a new fundamental constant in MOND. In recent years, theoretical and observational studies have shown that the star formation efficiency (SFE) of dense gas scales with surface density, SFE ∼ Σ/Σcrit with Σ_ crit_ ∼<{dot}p/m*>/(πG)∼1000 M☉ pc–2 (where <{dot}p/m*>is the momentum flux output by stellar feedback per unit stellar mass in a young stellar population). We argue that the SFE, more generally, should scale with the local gravitational acceleration, i.e. that SFE \simgtot/gcrit≡(G Mtot/R2)/ <{dot}p/m*>, where Mtot is the total gravitating mass and gcrit=<{dot}p/m*>= πG Σcrit ~10–8 cm s–2 ~g†. Hence, the observed g+ may correspond to the characteristic acceleration scale above which stellar feedback cannot prevent efficient star formation, and baryons will eventually come to dominate. We further show how this may give rise to the observed acceleration scaling gobs∼(gbaryon g†)1/2 (where gbaryon is the acceleration due to baryons alone) and flat rotation curves. The derived characteristic acceleration g+ can be expressed in terms of fundamental constants (gravitational constant, proton mass, and Thomson cross-section): g†∼0.1 G m_ p/σT_.
Abstract Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
galaxies: evolution - galaxies: formation - cosmology: dark matter
Simbad objects:
1
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