skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Structure formation in a mixed dark matter model with decaying sterile neutrino: the 3.5 keV X-ray line and the Galactic substructure

Abstract

We perform a set of cosmological simulations of structure formation in a mixed dark matter (MDM) model. Our model is motivated by the recently identified 3.5 keV X-ray line, which can be explained by the decay of non-resonantly produced sterile neutrinos accounting for 20–60% of the dark matter in the Universe. These non-resonantly produced sterile neutrinos have a sizable free-streaming length and hence behave effectively as warm dark matter (WDM). Assuming the rest of dark matter is composed of some cold dark matter (CDM) particles, we follow the coevolution of a mixed WDM plus CDM cosmology. Specifically, we consider the models with the warm component fraction of r{sub warm}=0.25 and 0.50. Our MDM models predict that the comoving Jeans length at the matter-radiation equality is close to that of the thermally produced warm dark matter model with particle mass m{sub WDM}=2.4 keV, but the suppression in the fluctuation power spectrum is weaker. We perform large N-body simulations to study the structure of non-linear dark halos in the MDM models. The abundance of substructure is significantly reduced in the MDM models, and hence the so-called small-scale crisis is mitigated. The cumulative maximum circular velocity function (CVF) of at least one halo in themore » MDM models is in good agreement with the CVFs of the observed satellites in the Milky Way and the Andromeda galaxy. We argue that the MDM models open an interesting possibility to reconcile the reported 3.5 keV line and the internal structure of galaxies.« less

Authors:
 [1];  [2]
  1. Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan (Japan)
  2. Kavli IPMU (WPI), University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa-shi, Chiba, 277-8583 Japan (Japan)
Publication Date:
OSTI Identifier:
22525060
Resource Type:
Journal Article
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2016; Journal Issue: 01; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; COSMOLOGICAL MODELS; COSMOLOGY; FLUCTUATIONS; KEV RANGE; MASS; MILKY WAY; NONLINEAR PROBLEMS; NONLUMINOUS MATTER; SATELLITES; UNIVERSE; X RADIATION

Citation Formats

Harada, Akira, and Kamada, Ayuki. Structure formation in a mixed dark matter model with decaying sterile neutrino: the 3.5 keV X-ray line and the Galactic substructure. United States: N. p., 2016. Web. doi:10.1088/1475-7516/2016/01/031.
Harada, Akira, & Kamada, Ayuki. Structure formation in a mixed dark matter model with decaying sterile neutrino: the 3.5 keV X-ray line and the Galactic substructure. United States. https://doi.org/10.1088/1475-7516/2016/01/031
Harada, Akira, and Kamada, Ayuki. 2016. "Structure formation in a mixed dark matter model with decaying sterile neutrino: the 3.5 keV X-ray line and the Galactic substructure". United States. https://doi.org/10.1088/1475-7516/2016/01/031.
@article{osti_22525060,
title = {Structure formation in a mixed dark matter model with decaying sterile neutrino: the 3.5 keV X-ray line and the Galactic substructure},
author = {Harada, Akira and Kamada, Ayuki},
abstractNote = {We perform a set of cosmological simulations of structure formation in a mixed dark matter (MDM) model. Our model is motivated by the recently identified 3.5 keV X-ray line, which can be explained by the decay of non-resonantly produced sterile neutrinos accounting for 20–60% of the dark matter in the Universe. These non-resonantly produced sterile neutrinos have a sizable free-streaming length and hence behave effectively as warm dark matter (WDM). Assuming the rest of dark matter is composed of some cold dark matter (CDM) particles, we follow the coevolution of a mixed WDM plus CDM cosmology. Specifically, we consider the models with the warm component fraction of r{sub warm}=0.25 and 0.50. Our MDM models predict that the comoving Jeans length at the matter-radiation equality is close to that of the thermally produced warm dark matter model with particle mass m{sub WDM}=2.4 keV, but the suppression in the fluctuation power spectrum is weaker. We perform large N-body simulations to study the structure of non-linear dark halos in the MDM models. The abundance of substructure is significantly reduced in the MDM models, and hence the so-called small-scale crisis is mitigated. The cumulative maximum circular velocity function (CVF) of at least one halo in the MDM models is in good agreement with the CVFs of the observed satellites in the Milky Way and the Andromeda galaxy. We argue that the MDM models open an interesting possibility to reconcile the reported 3.5 keV line and the internal structure of galaxies.},
doi = {10.1088/1475-7516/2016/01/031},
url = {https://www.osti.gov/biblio/22525060}, journal = {Journal of Cosmology and Astroparticle Physics},
issn = {1475-7516},
number = 01,
volume = 2016,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 2016},
month = {Fri Jan 01 00:00:00 EST 2016}
}