The root-mean-square of non-relativistic warm dark matter particle velocities scales as v<sub>hrms</sub>(a)=v<sub>hrms</sub>(1)/a , where a is the expansion parameter of the universe. This velo...The root-mean-square of non-relativistic warm dark matter particle velocities scales as v<sub>hrms</sub>(a)=v<sub>hrms</sub>(1)/a , where a is the expansion parameter of the universe. This velocity dispersion results in a cut-off of the power spectrum of density fluctuations due to dark matter free-streaming. Let k<sub>fs </sub>(t<sub>eq</sub>) be the free-streaming comoving cut-off wavenumber at the time of equal densities of radiation and matter. We obtain , and , at 68% confidence, from the observed distributions of galaxy stellar masses and rest frame ultra-violet luminosities. This result is consistent with reionization. From the velocity dispersion cut-off mass we obtain the limits v<sub>hrms</sub>(1)k<sub>fs </sub>(t<sub>eq</sub>) >1.5 Mpc<sup>-1</sup>. These results are in agreement with previous measurements based on spiral galaxy rotation curves, and on the formation of first galaxies and reionization. These measured parameters determine the temperature-to-mass ratio of warm dark matter. This ratio happens to be in agreement with the no freeze-in and no freeze-out warm dark matter scenario of spin 0 dark matter particles decoupling early on from the standard model sector. Spin 1/2 and spin 1 dark matter are disfavored if nature has chosen the no freeze-in and no freeze-out scenario. An extension of the standard model of quarks and leptons, with scalar dark matter that couples to the Higgs boson that is in agreement with all current measurements, is briefly reviewed. Discrepancies with limits on dark matter particle mass that can be found in the literature are addressed.展开更多
We developed a new semi-analytic galaxy formation model: Galaxy Assembly with Binary Evolution(GABE). For the first time, we introduce binary evolution into semi-analytic models of galaxy formation by using the Yunnan...We developed a new semi-analytic galaxy formation model: Galaxy Assembly with Binary Evolution(GABE). For the first time, we introduce binary evolution into semi-analytic models of galaxy formation by using the Yunnan-Ⅱ stellar population synthesis model, which includes various binary interactions. When implementing our galaxy formation model onto the merger trees extracted from the Millennium simulation, it can reproduce a large body of observational results. We find that in the local universe, the model including binary evolution reduces the luminosity at optical and infrared wavelengths slightly, but it increases the luminosity at ultraviolet wavelengths significantly, especially in FUV band. The resulting luminosity function does not change very much over SDSS optical bands and infrared band, but the predicted colors are bluer, especially when the FUV band is under consideration. The new model allows us to explore the physics of various high energy events related to the remnants of binary stars, such as type Ia supernovae, short gamma-ray bursts and gravitational wave events, and their relation with host galaxies in a cosmological context.展开更多
文摘The root-mean-square of non-relativistic warm dark matter particle velocities scales as v<sub>hrms</sub>(a)=v<sub>hrms</sub>(1)/a , where a is the expansion parameter of the universe. This velocity dispersion results in a cut-off of the power spectrum of density fluctuations due to dark matter free-streaming. Let k<sub>fs </sub>(t<sub>eq</sub>) be the free-streaming comoving cut-off wavenumber at the time of equal densities of radiation and matter. We obtain , and , at 68% confidence, from the observed distributions of galaxy stellar masses and rest frame ultra-violet luminosities. This result is consistent with reionization. From the velocity dispersion cut-off mass we obtain the limits v<sub>hrms</sub>(1)k<sub>fs </sub>(t<sub>eq</sub>) >1.5 Mpc<sup>-1</sup>. These results are in agreement with previous measurements based on spiral galaxy rotation curves, and on the formation of first galaxies and reionization. These measured parameters determine the temperature-to-mass ratio of warm dark matter. This ratio happens to be in agreement with the no freeze-in and no freeze-out warm dark matter scenario of spin 0 dark matter particles decoupling early on from the standard model sector. Spin 1/2 and spin 1 dark matter are disfavored if nature has chosen the no freeze-in and no freeze-out scenario. An extension of the standard model of quarks and leptons, with scalar dark matter that couples to the Higgs boson that is in agreement with all current measurements, is briefly reviewed. Discrepancies with limits on dark matter particle mass that can be found in the literature are addressed.
基金support from the National Key Program for Science and Technology Research and Development (2015CB857005, 2017YFB0203300)the National Natural Science Foundation of China (Grant Nos. 11390372, 11425312, 11503032, 11573031, 11851301, 11873051, 11573062, 11521303, 11390734, 11573033, 11622325 and 11573030)+3 种基金support from the YIPACAS Foundation (Grant No. 2012048)the Yunnan Foundation (2011CI053)supported by the Newton Advanced FellowshipJP acknowledges support from the National Basic Research Program of China (program 973,2015CB857001)
文摘We developed a new semi-analytic galaxy formation model: Galaxy Assembly with Binary Evolution(GABE). For the first time, we introduce binary evolution into semi-analytic models of galaxy formation by using the Yunnan-Ⅱ stellar population synthesis model, which includes various binary interactions. When implementing our galaxy formation model onto the merger trees extracted from the Millennium simulation, it can reproduce a large body of observational results. We find that in the local universe, the model including binary evolution reduces the luminosity at optical and infrared wavelengths slightly, but it increases the luminosity at ultraviolet wavelengths significantly, especially in FUV band. The resulting luminosity function does not change very much over SDSS optical bands and infrared band, but the predicted colors are bluer, especially when the FUV band is under consideration. The new model allows us to explore the physics of various high energy events related to the remnants of binary stars, such as type Ia supernovae, short gamma-ray bursts and gravitational wave events, and their relation with host galaxies in a cosmological context.
