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Astrophysical effects of scalar dark matter miniclusters

Zurek, Kathryn M. and Hogan, Craig J. and Quinn, Thomas R. (2007) Astrophysical effects of scalar dark matter miniclusters. Physical Review D, 75 (4). Art. No. 043511. ISSN 1550-7998. doi:10.1103/physrevd.75.043511.

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We model the formation, evolution and astrophysical effects of dark compact Scalar Miniclusters (“ScaMs”). These objects arise when a scalar field, with an axion-like or Higgs-like potential, undergoes a second-order phase transition below the QCD scale. Such a scalar field may couple too weakly to the standard model to be detectable directly through particle interactions, but may still be detectable by gravitational effects, such as lensing and baryon accretion by large, gravitationally bound miniclusters. The masses of these objects are shown to be constrained by the Lyα power spectrum to be less than ∼10^4 M_⊙, but they may be as light as classical axion miniclusters, of the order of 10^(−12) M_⊙. We simulate the formation and nonlinear gravitational collapse of these objects around matter-radiation equality using an N-body code, estimate their gravitational lensing properties, and assess the feasibility of studying them using current and future lensing experiments. Future MACHO-type variability surveys of many background sources can reveal either high-amplification, strong-lensing events, or measure density profiles directly via weak-lensing variability, depending on ScaM parameters and survey depth. However, ScaMs, due to their low internal densities, are unlikely to be responsible for apparent MACHO events already detected in the Galactic halo. As a result, in the entire window between 10^(−7) M_⊙ and 10^2 M_⊙covered by the galactic scale lensing experiments, ScaMs may in fact compose all the dark matter. A simple estimate is made of parameters that would give rise to early structure formation; in principle, early stellar collapse could be triggered by ScaMs as early as recombination, and significantly affect cosmic reionization.

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Additional Information:© 2007 American Physical Society. (Received 26 July 2006; published 14 February 2007) This work was supported by NSF grant No. AST-0098557 at the University of Washington.
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Issue or Number:4
Classification Code:PACS numbers: 95.35.+d, 98.80.Ft
Record Number:CaltechAUTHORS:20190611-125826499
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96284
Deposited By: George Porter
Deposited On:12 Jun 2019 17:15
Last Modified:16 Nov 2021 17:19

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