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

Harada, Akira; Kamada, Ayuki

doi:10.1088/1475-7516/2016/01/031

Cited by 21 publications

(21 citation statements)

References 197 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When m 3/2 mã, the free streaming length of gravitinos becomes independent of m 3/2 [59] and can be approximated by where the NLSP is the higgsino (axino) in the left (right) panels of figure 4. The analyses from Lyman-α forest [60][61][62] place an upper bound on the dark matter free streaming length, λ FS < ∼ 1 Mpc. As a result, for m NLSP ≈ 650 GeV there is a sizable component of warm dark matter in the parameter space close to the boundaries of the green regions.…”

Section: Jhep07(2017)125mentioning

confidence: 99%

Saxion cosmology for thermalized gravitino dark matter

DʼEramo

Hall

et al. 2017

J. High Energ. Phys.

View full text Add to dashboard Cite

In all supersymmetric theories, gravitinos, with mass suppressed by the Planck scale, are an obvious candidate for dark matter; but if gravitinos ever reached thermal equilibrium, such dark matter is apparently either too abundant or too hot, and is excluded. However, in theories with an axion, a saxion condensate is generated during an early era of cosmological history and its late decay dilutes dark matter. We show that such dilution allows previously thermalized gravitinos to account for the observed dark matter over very wide ranges of gravitino mass, keV < m 3/2 < TeV, axion decay constant, 10 9 GeV < f a < 10 16 GeV, and saxion mass, 10 MeV < m s < 100 TeV. Constraints on this parameter space are studied from BBN, supersymmetry breaking, gravitino and axino production from freeze-in and saxion decay, and from axion production from both misalignment and parametric resonance mechanisms. Large allowed regions of (m 3/2 , f a , m s ) remain, but differ for DFSZ and KSVZ theories. Superpartner production at colliders may lead to events with displaced vertices and kinks, and may contain saxions decaying to (W W, ZZ, hh), gg, γγ or a pair of Standard Model fermions. Freeze-in may lead to a sub-dominant warm component of gravitino dark matter, and saxion decay to axions may lead to dark radiation.

show abstract

Section: Jhep07(2017)125mentioning

confidence: 99%

Saxion cosmology for thermalized gravitino dark matter

DʼEramo

Hall

et al. 2017

J. High Energ. Phys.

View full text Add to dashboard Cite

show abstract

“…These constraints are so strong that they exclude WDM as a solution to the small scale tensions or leave only a small parameter region if any [82]. One may wonder if we can alleviate the tight constraints by considering a mixed DM model, where DM consists of cold and warm components [83][84][85]. The recent analysis of Ly-α forest data, on the other hand, may disfavor even a mixed DM model as a solution to the small scale crisis [86].…”

Section: 5 Kev Signals and Ly-α Forest Constraintmentioning

confidence: 99%

Light axinos from freeze-in: production processes, phase space distributions, and Ly-α forest constraints

Bae

Kamada

Liew

et al. 2018

J. Cosmol. Astropart. Phys.

Self Cite

View full text Add to dashboard Cite

We consider the freeze-in production of 7 keV axino dark matter (DM) in the supersymmetric Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model in light of the 3.5 keV line excess.The warmness of such 7 keV DM produced from the thermal bath, in general, appears in tension with Ly-α forest data, although a direct comparison is not straightforward. This is because the Ly-α forest constraints are usually reported on the mass of the conventional warm dark matter (WDM), where large entropy production is implicitly assumed to occur in the thermal bath after WDM particles decouple. The phase space distribution of freeze-in axino DM varies depending on production processes and axino DM may alleviate the tension with the tight Ly-α forest constraint. By solving the Boltzmann equation, we first obtain the resultant phase space distribution of axinos produced by 2-body decay, 3-body decay, and 2-to-2 scattering respectively. The reduced collision term and resultant phase space distribution are useful for studying other freeze-in scenarios as well. We then calculate the resultant linear matter power spectra for such axino DM and directly compare them with the linear matter power spectra for the conventional WDM. In order to demonstrate realistic axino DM production, we consider benchmark points with Higgsino next-to-light supersymmetric particle (NLSP) and wino NLSP. In the case of Higgsino NLSP, the phase space distribution of axinos is colder than that in the conventional WDM case, so the most stringent Ly-α forest constraint can be evaded with mild entropy production from saxion decay inherent in the supersymmetric DFSZ axion model.

show abstract

“…The LSP is a gauge singlet extremely weakly coupled to the radiation bath, and thus DM particles coming from NLSP decays just lose their momenta by pure free streaming. This has the effect of potentially washing out cosmological perturbations at small scales through free streaming, and this scenario is severely constrained by Lyman-α forest observations [43][44][45], bounding the free streaming length to be less than 1 Mpc. Interestingly, if the free streaming length is consistent with large scale structure and not too small it can address some large scale structure (LSS) issues that are indicated by simulations of collisionless cold dark matter [46].…”

Section: Warm Dark Matter From Nlsp Decaysmentioning

confidence: 99%

Gravitino or axino dark matter with reheat temperature as high as 1016 GeV

DʼEramo

Hall

2017

J. High Energ. Phys.

View full text Add to dashboard Cite

A new scheme for lightest supersymmetric particle (LSP) dark matter is introduced and studied in theories of TeV supersymmetry with a QCD axion, a, and a high reheat temperature after inflation, T R . A large overproduction of axinos (ã) and gravitinos (G) from scattering at T R , and from freeze-in at the TeV scale, is diluted by the late decay of a saxion condensate that arises from inflation. The two lightest superpartners areã, with mass of order the TeV scale, andG with mass m 3/2 anywhere between the keV and TeV scales, depending on the mediation scale of supersymmetry breaking. Dark matter contains both warm and cold components: forG LSP the warm component arises fromã →Ga, while forã LSP the warm component arises fromG →ãa. The free-streaming scale for the warm component is predicted to be of order 1 Mpc (and independent of m 3/2 in the case ofG LSP). T R can be as high as 10 16 GeV, for any value of m 3/2 , solving the gravitino problem. The PQ symmetry breaking scale V PQ depends on T R and m 3/2 and can be anywhere in the range (10 10 − 10 16 ) GeV. Detailed predictions are made for the lifetime of the neutralino LOSP decaying toã+h/Z andG+h/Z/γ, which is in the range of (10 −1 −10 6 )m over much of parameter space. For an axion misalignment angle of order unity, the axion contribution to dark matter is sub-dominant, except when V PQ approaches 10 16 GeV.

show abstract

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

Cited by 21 publications

References 197 publications

Saxion cosmology for thermalized gravitino dark matter

Saxion cosmology for thermalized gravitino dark matter

Light axinos from freeze-in: production processes, phase space distributions, and Ly-α forest constraints

Gravitino or axino dark matter with reheat temperature as high as 1016 GeV

Contact Info

Product

Resources

About