![]() We release a new branch of the CLASS code, called CLASSNET, which automatically uses networks within a region of trusted accuracy. In this second CosmicNet paper, we present a more efficient set of networks that are already trained for extended cosmologies beyond LCDM, with massive neutrinos, extra relativistic degrees of freedom, spatial curvature, and dynamical dark energy. This strategy offers advantages compared to the direct emulation of the final observables, including small networks that are easy to train in high-dimensional parameter spaces, and which do not depend by on primordial spectrum parameters nor observation-related quantities such as selection functions. To accelerate the computation of these observables, the CosmicNet strategy is to replace the bottleneck of an EBS, which is the integration of a system of differential equations for linear cosmological perturbations, by neural networks. In modern analysis pipelines, Einstein-Boltzmann Solvers (EBSs) are an invaluable tool for obtaining CMB and matter power spectra. When considering ratios between the matter power spectrum computed in a given cosmological model and its $\Lambda$CDM counterpart, all the tested prescriptions agree with simulated data, at sub-percent or percent level, depending on $z$. At $z>0$ we do not find a similar improvement when including massive neutrinos, probably due to the lower impact of neutrino free-streaming at higher redshifts rather at $z=2$ EuclidEmulator2 exceeds $2\%$ agreement for some dark energy EoS. In cosmologies with massive neutrinos, at $z=0$ all the nonlinear prescriptions improve their agreement with respect to the massless neutrino case, except for the Bird and TakaBird models which, however, are not tailored to $w_0$-$w_a$ models. baccoemu has a similar behaviour as EuclidEmulator2, except for a couple of dark energy models. ![]() Concerning emulators, we find that, especially at low redshifts, EuclidEmulator2 remarkably agrees with the simulated spectra at $\lesssim 1\%$ level in scenarios with dynamical dark energy and massless neutrinos, reaching a maximum difference of $\sim 2\%$ at $z=2$. Focussing on redshifts $z\leq2$ and scales $k\lesssim 1 \ h/$Mpc (where the simulation mass resolution provides $\sim 1\%$ accuracy), we find that HMcode and ReACT considerably improve over the HALOFIT prescriptions of Smith and Takahashi (both combined with the Bird correction), with an overall agreement of 2\% for all the cosmological scenarios considered. ![]() We test the current most widely used approaches: fitting functions (HALOFIT and HMcode), the halo-model reaction (ReACT) and emulators (baccoemu and EuclidEmulator2). We provide an accurate comparison, against large cosmological $N$-body simulations, of different prescriptions for modelling nonlinear matter power spectra in the presence of massive neutrinos and dynamical dark energy. We show that overall $\lesssim 5\%$ errors can be achieved for the neutrino density and velocity transfer functions at redshift $z \lesssim 5$, which corresponds to an order of magnitude improvement over previous approximation schemes that can be discrepant by as much as a factor of two. In this work we account for the dispersive nature of the neutrino fluid, i.e., the scale dependence in the sound speed, leading to an improved fluid approximation. We investigate the exponential $f(Q)$ symmetric teleparallel gravitation, namely $f(Q)=Q \alpha Q_0(1-e^$. Specific gauges, but are derived here in a completely transparent Our results confirm those obtainedīy other groups, who have worked carefully with non-covariant methods in Solutions in the early radiation dominated era, and the numerical Integral solution and relation with the line of sight approach, analytic We discuss the scalar equations in detail, including the Perturbations, which are valid for any value of the backgroundĬurvature, are obtained straightforwardly from the complete set ofĮquations. Frame-independent equations for scalar and tensor TheseĮquations include the contributions of scalar, vector and tensor modes (Boltzmann) evolution of anisotropy and inhomogeneity in an almostįriedmann-Robertson-Walker (FRW) cold dark matter (CDM) universe. ![]() We derive theĬomplete set of frame-independent, linearised equations describing the ![]() Gauge-invariant and have a clear physical interpretation. We use the physically appealing covariant approach toĬosmological perturbations, which ensures that all variables are We present a fully covariant and gauge-invariant calculation of theĮvolution of anisotropies in the cosmic microwave background (CMB) ![]()
0 Comments
Leave a Reply. |