3.5 keV galactic emission line as a signal from the hidden sector

Chen, Ning; Liu, Zuowei; Nath, Pran

doi:10.1103/physrevd.90.035009

Cited by 8 publications

(1 citation statement)

References 48 publications

(49 reference statements)

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“…The flux of such a monochromatic photon line at the X-ray energy E γ = 3.56 keV is measured to be Φ γγ = 5.2 +3.70 −2.13 × 10 −5 ph cm −2 s −1 [17]. Although the source of this X-ray line signal is still unclear, the DM annihilation (or decay) into photons is a well motivated possibility [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Considering the Perseus Mass 1.49 × 10 14 M and the distance between the Perseus cluster and the solar system 78 Mpc, the photon-line flux from DM annihilation can be written as…”

Section: X-raymentioning

confidence: 99%

Non-abelian dark matter solutions for Galactic gamma-ray excess and Perseus 3.5 keV X-ray line

Cheung

Huang

Tsai

2015

J. Cosmol. Astropart. Phys.

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We attempt to explain simultaneously the Galactic center gamma-ray excess and the 3.5 keV X-ray line from the Perseus cluster based on a class of non-abelian SU (2) DM models, in which the dark matter and an excited state comprise a "dark" SU (2) doublet. The non-abelian group kinetically mixes with the standard model gauge group via dimensions-5 operators. The dark matter particles annihilate into standard model fermions, followed by fragmentation and bremsstrahlung, and thus producing a continuous spectrum of gamma-rays. On the other hand, the dark matter particles can annihilate into a pair of excited states, each of which decays back into the dark matter particle and an X-ray photon, which has an energy equal to the mass difference between the dark matter and the excited state, which is set to be 3.5 keV. The large hierarchy between the required X-ray and γ-ray annihilation cross-sections can be achieved by a very small kinetic mixing between the SM and dark sector, which effectively suppresses the annihilation into the standard model fermions but not into the excited state.A gamma-ray excess around a few GeV near the Galactic center (GC) region, seen by the Fermi-LAT collaboration (see, for instance, the recent analysis by the collaboration [1]), has been widely discussed based on dark matter (DM) annihilations into standard model (SM) fermions [2][3][4][5][6][7][8][9][10][11][12][13][14][15], which hadronize into neutral pions followed by π 0 → γγ, or electromagnetic bremsstrahlung. On the other hand, recent reports of the 3.5 keV X-ray line [16,17] from the XMM-Newton data have triggered many studies in the context of DM, for example, Refs. . Roughly speaking, they can be classified into two categories: (i) DM undergoes upscattering into an excited stated followed by the decay back into DM and an X-ray photon; and (ii) decaying DM matter, such as a 7 keV sterile neutrino decaying into an active neutrino and the X-ray photon. The excited DM, however, has a advantage of explaining some null results on X-ray line searches due to a low local DM velocity as shown in Ref [66].There is a very interesting connection between the γ-ray excess and X-ray line as follows. The GC γ-ray excess can be explained by annihilating DM with a mass from 10 to 60 GeV [2, 5-8, 10-12], depending on the final state of the annihilation. On the other hand, due to the fact that the current DM velocity is around 10 −3 c in the Perseus cluster, where the X-ray line is observed, the DM with a mass of 10 to 60 GeV coincidently has a kinetic energy of a few keV. It implies if there exists an excited state with a 3.5 keV mass splitting from the DM particle, then the DM particles can annihilate into the excited state, followed by the decay back into the DM particle with a photon accounting for the observed X-ray line.In this work, we employ a class of non-abelian SU (2) X DM models proposed in Refs. [18,67], where the DM particle and the excited state form an SU (2) X doublet with a 3.5 keV mass splitting. The SU (2) X kinetically mixes with ...

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Section: X-raymentioning

confidence: 99%

Non-abelian dark matter solutions for Galactic gamma-ray excess and Perseus 3.5 keV X-ray line

Cheung

Huang

Tsai

2015

J. Cosmol. Astropart. Phys.

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ν Dark matter-philic Higgs for 3.5 keV X-ray signal

2015

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Editor: J. HisanoWe suggest a new model of 7 keV right-handed neutrino dark matter inspired by a recent observation of 3.5 keV X-ray line signal in the XMM-Newton observatory. It is difficult to derive the tiny masses with a suitable left-right mixing of the neutrino in a framework of ordinary simple type-I seesaw mechanism. We introduce a new Higgs boson, a dark matter-philic Higgs boson, in which the smallness of its vacuum expectation value can be achieved. We investigate suitable parameter regions where the observed dark matter properties are satisfied. We find that the vacuum expectation value of dark matter-philic Higgs boson should be about 0.17 GeV.

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

Harada

Kamada

2016

J. Cosmol. Astropart. Phys.

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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 Xray 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 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 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.

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3.5 keV galactic emission line as a signal from the hidden sector

Cited by 8 publications

References 48 publications

Non-abelian dark matter solutions for Galactic gamma-ray excess and Perseus 3.5 keV X-ray line

Non-abelian dark matter solutions for Galactic gamma-ray excess and Perseus 3.5 keV X-ray line

ν Dark matter-philic Higgs for 3.5 keV X-ray signal

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

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