Central MONDian spike in spherically symmetric systems
Por:
Hernandez, X.
Publicada:
1 ago 2017
Resumen:
Under a MONDian view, astrophysical systems are expected to follow
Newtonian dynamics whenever the local acceleration is above the critical
a(0) = 1.2 x 10(-10) ms(-2), and enter a modified regime for
accelerations below this critical value. Indeed, the dark matter
phenomenology on galactic and subgalactic scales appears always, and
only, at low accelerations. It is standard to find the a < a(0) regime
towards the low density outskirts of astronomical systems, where under a
Newtonian interpretation, dark matter becomes conspicuous. Thus, it is
standard to find, and to think, of the dense central regions of observed
systems as purely Newtonian. However, under spherical symmetry in the
MONDian as in the Newtonian case, the local acceleration will tend to
zero as one approaches the very centre of a mass distribution. It is
clear that for spherically symmetric systems, an inner a < a(0) region
will necessarily appear interior to a critical radius, which will depend
on the details of the density profile in question. Here, we calculate
analytically such a critical radius for a constant-density core, and
numerically for a cored isothermal profile. Under a Newtonian
interpretation, such a central MONDian region will be interpreted as
extra mass, analogous to the controversial black holes sometimes
inferred to lie at the centres of globular clusters, despite an absence
of nuclear activity detected to date. We calculate this effect and give
predictions for the `central black hole' mass to be expected under
Newtonian interpretations of low density Galactic globular clusters.
Filiaciones:
Hernandez, X.:
Univ Nacl Autonoma Mexico, Inst Astron, Apartado Postal 70-264, Ciudad De Mexico 04510, DF, Mexico
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