| 1. |
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Overview of the JET results
- 2015
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 55:10
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Tidskriftsartikel (refereegranskat)
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| 2. |
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| 3. |
- Bucko, Jozef, et al.
(författare)
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Constraining dark matter decay with cosmic microwave background and weak-lensing shear observations
- 2023
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 672
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Tidskriftsartikel (refereegranskat)abstract
- From observations at low and high redshifts, it is well known that the bulk of dark matter (DM) has to be stable or at least very long-lived. However, the possibility that a small fraction of DM is unstable or that all DM decays with a half-life time (tau) significantly longer than the age of the Universe is not ruled out. One-body decaying dark matter (DDM) consists of a minimal extension to the Lambda CDM model. It causes a modification of the cosmic growth history as well as a suppression of the small-scale clustering signal, providing interesting consequences regarding the S-8 tension, which is the observed di fference in the clustering amplitude between weak-lensing (WL) and cosmic microwave background (CMB) observations. In this paper, we investigate models in which a fraction or all DM decays into radiation, focusing on the long-lived regime, that is, tau greater than or similar to H-0(-1) (H-0(-1) being the Hubble time). We used WL data from the Kilo-Degree Survey (KiDS) and CMB data from Planck. First, we confirm that this DDM model cannot alleviate the S-8 di fference. We then show that the most constraining power for DM decay does not come from the nonlinear WL data, but from CMB via the integrated Sachs-Wolfe e ffect. From the CMB data alone, we obtain constraints of tau >= 288 Gyr if all DM is assumed to be unstable, and we show that a maximum fraction of f = 0.07 is allowed to decay assuming the half-life time to be comparable to (or shorter than) one Hubble time. The constraints from the KiDS-1000 WL data are significantly weaker, tau >= 60 Gyr and f < 0.34. Combining the CMB and WL data does not yield tighter constraints than the CMB alone, except for short half-life times, for which the maximum allowed fraction becomes f = 0.03. All limits are provided at the 95% confidence level.
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| 4. |
- Bucko, Jozef, et al.
(författare)
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Probing the two-body decaying dark matter scenario with weak lensing and the cosmic microwave background
- 2024
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 683
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Tidskriftsartikel (refereegranskat)abstract
- Decaying dark matter (DDM) scenarios have recently regained attention due to their potential ability to resolve the well-known clustering (or S8) tension between weak lensing (WL) and cosmic microwave background (CMB) measurements. In this paper, we investigate a well-established model where the original dark matter particle decays into a massless particle and a massive daughter particle. The latter obtains a velocity kick during the decay process that results in the suppression of the matter power spectrum at scales that are observable with WL shear observations. We perform the first fully non-linear WL analysis of this two-body decaying dark matter (ΛDDM) scenario, including intrinsic alignment and baryonic feedback processes. We used the cosmic shear band power spectra from KiDS-1000 data and combined it with temperature and polarisation data from Planck in order to constrain the ΛDDM model. We report new limits on the decay rate and mass splitting parameters that are significantly stronger than previous results, especially in the case of low-mass splittings. Regarding the S8 tension, we found a reduction from about 3 to 2σ, depending on which statistical measure is applied. We therefore conclude that the two-body ΛDDM model is able to reduce the S8 tension without convincingly solving it.
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| 5. |
- Bucko, Jozef, et al.
(författare)
-
Probing the two-body decaying dark matter scenario with weak lensing and the cosmic microwave background
- 2024
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 683
-
Tidskriftsartikel (refereegranskat)abstract
- Decaying dark matter (DDM) scenarios have recently regained attention due to their potential ability to resolve the well-known clustering (or S-8) tension between weak lensing (WL) and cosmic microwave background (CMB) measurements. In this paper, we investigate a well-established model where the original dark matter particle decays into a massless particle and a massive daughter particle. The latter obtains a velocity kick during the decay process that results in the suppression of the matter power spectrum at scales that are observable with WL shear observations. We perform the first fully non-linear WL analysis of this two-body decaying dark matter (Lambda DDM) scenario, including intrinsic alignment and baryonic feedback processes. We used the cosmic shear band power spectra from KiDS-1000 data and combined it with temperature and polarisation data from Planck in order to constrain the Lambda DDM model. We report new limits on the decay rate and mass splitting parameters that are significantly stronger than previous results, especially in the case of low-mass splittings. Regarding the S-8 tension, we found a reduction from about 3 to 2 sigma, depending on which statistical measure is applied. We therefore conclude that the two-body.DDM model is able to reduce the S-8 tension without convincingly solving it.
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| 6. |
- Hervas Peters, Fabian, et al.
(författare)
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Constraining hot dark matter sub-species with weak lensing and the cosmic microwave background radiation
- 2024
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 687
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Tidskriftsartikel (refereegranskat)abstract
- Although it is well known that the bulk of dark matter (DM) has to be cold, the existence of an additional sub-dominant, hot species remains a valid possibility. In this paper we investigate the potential of the cosmic shear power spectrum to constrain such a mixed (hot plus cold) DM scenario with two additional free parameters, the hot-to-total DM fraction (fhdm) and the thermal mass of the hot component (mhdm). Running a Bayesian inference analysis for both the Kilo-Degree Survey cosmic shear data (KiDS-1000) as well as the cosmic microwave background (CMB) temperature and polarisation data from Planck, we derive new constraints for the mixed DM scenario. We find a 95% confidence limit of fhdm 0:08 for a very hot species of mhdm ≤ 20 eV. This constraint is weakened to fhdm 0:25 for mhdm ≤ 80 eV. Scenarios with masses above mhdm ∼ 200 eV remain unconstrained by the data. Next to providing limits, we investigate the potential of mixed DM to address the clustering (or S 8) tension between lensing and the CMB. We find a reduction of the 2D (Ω m-S 8) tension from 2.9σ to 1.6σ when going from a pure cold DM to a mixed DM scenario. When computing the 1D Gaussian tension on S 8 the improvement is milder, from 2.4σ to 2.0σ.
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