اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدTowards the Chalonge Meudon Workshop 2013. Highlights and Conclusions of the Chalonge Meudon workshop 2012: warm dark matter galaxy formation in agreement with observations
134
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Warm Dark Matter(WDM), considerably clarifies and simplifies galaxies and galaxy formation in agreement with observations. WDM essentially works, naturally reproducing the astronomical observations over all scales, small (galactic) as well as large and cosmological scales.Evidence that CDM, CDM+baryons and proposed tailored cures do not work in galaxies is staggering, The Chalonge Meudon Workshop 2012 approached DM in a fourfold coherent way: astronomical observations (galaxy and cluster properties, haloes, rotation curves, density profiles, surface density), LambdaWDM N-body simulations, WDM theory (Boltzmann-Vlasov evolution, halo mass functions, halo models, improved perturbative approachs), quantum WDM fermions forming the observed cores, WDM particle and nuclear physics (sterile neutrinos) and its experimental search. N Amorisco, P Biermann, S Das, H J de Vega, A Kamada, E Ferri(MARE),I D Karanchetsev, W Liao, M Lovell, M Papastergis, N G Sanchez, P Valageas,C Watson, J Zavala,He Zhang present their Highlights.Inside galaxy cores, N-body classical physics simulations are incorrect for WDM because of important quantum effects at such scales.Quantum WDM calculations (Thomas-Fermi) provide galaxy cores, galaxy masses, velocity dispersions and density profiles in agreement with observations.Baryons (16% of DM) are expected to give a correction to pure WDM results. The summary and conclusions by H. J. de Vega and N. G. Sanchez stress that all evidences point to a DM particle mass around 2 keV. Peter Biermann in his live minutes concludes that a few keV sterile neutrino is the most serious DM candidate. MARE -and hopefully KATRIN- could provide a sterile neutrino signal.There is a formidable WDM work to perform ahead of us, these highlights point research directions worthwhile to pursue.Photos of the Workshop are included (Abridged).
قيم البحث
اقرأ أيضاً
LWDM (Warm Dark Matter) is progressing impressively.The galactic scale crisis and decline of LCDM+baryons are staggering. The 16th Paris Chalonge Colloquium 2012 combined real cosmological/astrophysical data and hard theory predictive approach in the
LWDM Standard Model. News and reviews from ACT,WMAP,SPT,QUIET,Planck,Herschel,JWST,UFFO,KATRIN and MARE experiments; astrophysics, particle and nuclear physics WDM searches, galactic observations, related theory and simulations, with the aim of synthesis and clarification. Here highlights by P Biermann, C Burigana, C Conselice, A Cooray, H de Vega, C Giunti & M Laveder, J Kormendi & K Freeman, E Ma, J Mather, L Page, G Smoot, N Sanchez. Summary and conclusions by de Vega, Falvella and Sanchez. Data confirm primordial CMB gaussianity. Effective (Ginsburg-Landau) Inflation theory predicts r about 0.04-0.05, negligeable running of ns, the inflation energy scale (GUT scale) and the set of CMB observables in agreement with the data. WMAP9 and Planck measurements are compatible with one or two Majorana sterile neutrinos in the eV mass scale. Cored (non cusped) DM halos and keV WDM are strongly favored by theory and observations, Wimps are strongly disfavoured. LambdaCDM with baryons do not work at small scales. Inside galaxy cores, quantum WDM effects are important. Quantum WDM calculations (Thomas-Fermi) provide galaxy masses, velocity dispersions and cored profiles and their sizes in agreement with observations. A WDM fermion of about 2 keV naturally reproduces galaxy, large scale and cosmological observations. WDM keV particles deserve dedicated astronomical and laboratory searches, theoretical work and numerical simulations. KATRIN can be adapted to look to keV scale sterile neutrinos. It will be a fantastic discovery to detect dark matter in beta decay. Photos of the Colloquium are included
Analytic formulas reproducing the warm dark matter (WDM) primordial spectra are obtained for WDM particles decoupling in and out of thermal equilibrium which provide the initial data for WDM non-linear structure formation. We compute and analyze the
corresponding WDM overdensities and compare them to the CDM case. We consider the ratio of the WDM to CDM primordial spectrum and the WDM to CDM overdensities: they turn to be self-similar functions of k/k_{1/2} and R/R_{1/2} respectively, k_{1/2} and R_{1/2} being the wavenumber and length where the WDM spectrum and overdensity are 1/2 of the respective CDM magnitudes. Both k_{1/2} and R_{1/2} show scaling as powers of the WDM particle mass m while the self-similar functions are independent of m. The WDM primordial spectrum sharply decreases around k_{1/2} with respect to the CDM spectrum, while the WDM overdensity slowly decreases around R_{1/2}. The nonlinear regions where WDM structure formation takes place are shown and compared to those in CDM: the WDM non-linear structures start to form later than in CDM, and as a general trend, decreasing the DM particle mass delays the onset of the non-linear regime. The non-linear regime starts earlier for smaller objects than for larger ones; smaller objects can form earlier both in WDM and CDM. We compute and analyze the differential mass function dN/dM for WDM at redshift z in the Press-Schechter approach. The WDM suppression effect of small scale structure increases with the redshift z. Our results for dN/dM are useful to be contrasted with observations, in particular for 4 < z < 12. We perfom all these studies for the most popular WDM particle physics models. Contrasting them to observations should point out the precise value of the WDM particle mass in the keV scale, and help to single out the best WDM particle physics model (Abridged).
We consider the models of vacuum energy interacting with cold dark matter in this study, in which the coupling can change sigh during the cosmological evolution. We parameterize the running coupling $b$ by the form $b(a)=b_0a+b_e(1-a)$, where at the
early-time the coupling is given by a constant $b_{e}$ and today the coupling is described by another constant $b_{0}$. We explore six specific models with (i) $Q(a)=b(a)H_0rho_0$, (ii) $Q(a)=b(a)H_0rho_{rm de}$, (iii) $Q(a)=b(a)H_0rho_{rm c}$, (iv) $Q(a)=b(a)Hrho_0$, (v) $Q(a)=b(a)Hrho_{rm de}$, and (vi) $Q(a)=b(a)Hrho_{rm c}$. The current observational data sets we use to constrain the models include the JLA compilation of type Ia supernova data, the Planck 2015 distance priors data of cosmic microwave background observation, the baryon acoustic oscillations measurements, and the Hubble constant direct measurement. We find that, for all the models, we have $b_0<0$ and $b_e>0$ at around the 1$sigma$ level, and $b_0$ and $b_e$ are in extremely strong anti-correlation. Our results show that the coupling changes sign during the evolution at about the 1$sigma$ level, i.e., the energy transfer is from dark matter to dark energy when dark matter dominates the universe and the energy transfer is from dark energy to dark matter when dark energy dominates the universe.
The Reduced Relativistic Gas (RRG) model was introduced by A. Sakharov in 1965 for deriving the cosmic microwave background (CMB) spectrum. It was recently reinvented by some of us to achieve an interpolation between the radiation and dust epochs in
the evolution of the Universe. This model circumvents the complicated structure of the Boltzmann-Einstein system of equations and admits a transparent description of warm-dark-matter effects. It is extended here to include, on a phenomenological basis, an out-of-equilibrium interaction between radiation and baryons which is supposed to account for relevant aspects of pre-recombination physics in a simplified manner. Furthermore, we use the tight-coupling approximation to explore the influence of both this interaction and of the RRG warmness parameter on the anisotropy spectrum of the CMB. The predictions of the model are very similar to those of the {Lambda}CDM model if both the interaction and the dark-matter warmness parameters are of the order of $10^{-4}$ or smaller. As far as the warmness parameter is concerned, this is in good agreement with previous estimations on the basis of results from structure formation.
We use the Copernicus Complexio (COCO) high resolution $N$-body simulations to investigate differences in the properties of small-scale structures in the standard cold dark matter (CDM) model and in a model with a cutoff in the initial power spectrum
of density fluctuations consistent with both a thermally produced warm dark matter (WDM) particle or a sterile neutrino with mass 7 keV and leptogenesis parameter $L_6=8.7$. The latter corresponds to the coldest model with this sterile neutrino mass compatible with the identification of the recently detected 3.5 keV X-ray line as resulting from particle decay. CDM and WDM predict very different number densities of subhaloes with mass $leq 10^9,h^{-1},M_odot$ although they predict similar, nearly universal, normalised subhalo radial density distributions. Haloes and subhaloes in both models have cuspy NFW profiles, but WDM subhaloes below the cutoff scale in the power spectrum (corresponding to maximum circular velocities $V_{mathrm{max}}^{z=0} leq50~mathrm{kms}^{-1}$) are less concentrated than their CDM counterparts. We make predictions for observable properties using the GALFORM semi-analytic model of galaxy formation. Both models predict Milky Way satellite luminosity functions consistent with observations, although the WDM model predicts fewer very faint satellites. This model, however, predicts slightly more UV bright galaxies at redshift $z>7$ than CDM, but both are consistent with observations. Gravitational lensing offers the best prospect of distinguishing between the models.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
