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Title: The universal acceleration scale from stellar feedback
ABSTRACT It has been established for decades that rotation curves deviate from the Newtonian gravity expectation given baryons alone below a characteristic acceleration scale $$g_{\dagger }\sim 10^{-8}\, \rm {cm\, s^{-2}}$$, 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 $$\Sigma _{\rm crit} \sim \langle \dot{p}/m_{\ast }\rangle /(\pi \, G)\sim 1000\, \rm {M_{\odot }\, pc^{-2}}$$ (where $$\langle \dot{p}/m_{\ast }\rangle$$ 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 $${\sim}g_{\rm tot}/g_{\rm crit}\equiv (G\, M_{\rm tot}/R^{2}) / \langle \dot{p}/m_{\ast }\rangle$$, where Mtot is the total gravitating mass and $$g_{\rm crit}=\langle \dot{p}/m_{\ast }\rangle = \pi \, G\, \Sigma _{\rm crit} \approx 10^{-8}\, \rm {cm\, s^{-2}} \approx \mathit{ g}_{\dagger }$$. 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 $$g_{\rm obs}\sim (g_{\rm baryon}\, g_{\dagger })^{1/2}$$ (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): $$g_{\dagger }\sim 0.1\, G\, m_{\mathrm{ p}}/\sigma _{\rm T}$$.  more » « less
Award ID(s):
1752913 1910346 1715216 1652522 1715847
PAR ID:
10174809
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Monthly Notices of the Royal Astronomical Society: Letters
Volume:
496
Issue:
1
ISSN:
1745-3925
Page Range / eLocation ID:
L127 to L132
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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