Collapsed Dark Matter Structures.

Matthew R Buckley,Anthony Difranzo

doi:10.1103/physrevlett.120.051102

Matthew R Buckley, Anthony Difranzo

Open Access

https://doi.org/10.1103/physrevlett.120.051102

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Abstract

The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

Highlights

The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells
Even models of self-interacting dark matter, which can alter the morphology of dark matter halos [12], do not allow for the loss of energy but only the transfer of energy between dark matter particles
Necessary interactions to dissipate energy, because such interactions would seem to violate the known shape of dark matter halos at the scale of dwarf galaxies and larger, which are largely consistent with the predictions of noninteracting, noncooling, cold dark matter (CDM) [13,14]

Summary

Collapsed Dark Matter Structures

The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. Necessary interactions to dissipate energy, because such interactions would seem to violate the known shape of dark matter halos at the scale of dwarf galaxies and larger, which are largely consistent with the predictions of noninteracting, noncooling, cold dark matter (CDM) [13,14] This is not the case: Cooling mechanisms generically operate efficiently only within a relatively narrow range of halo masses set by the parameters of the dark sector.

Published by the American Physical Society

Findings

Mmin rDAO