Article

# Halo concentration and the dark matter power spectrum

Department of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544, USA

Monthly Notices of the Royal Astronomical Society (Impact Factor: 5.52). 03/2003; 340(4):1199 - 1204. DOI: 10.1046/j.1365-8711.2003.06372.x Source: arXiv

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**ABSTRACT:**We recently developed a generalization of the halo model in order to describe the spatial clustering properties of each mass component in the Universe, including hot gas and stars. In this work we discuss the complementarity of the model with respect to a set of cosmological simulations including hydrodynamics of different kinds. We find that the mass fractions and density profiles measured in the simulations do not always succeed in reproducing the simulated matter power spectra, the reason being that the latter encode information from a much larger range in masses than that accessible to individually resolved structures. In other words, this halo model allows one to extract information on the growth of structures from the spatial clustering of matter, that is complementary with the information coming from the study of individual objects. We also find a number of directions for improvement of the present implementation of the model, depending on the specific application one has in mind. The most relevant one is the necessity for a scale dependence of the bias of the diffuse gas component, which will be interesting to test with future detections of the Warm-Hot Intergalactic Medium. This investigation confirms the possibility to gain information on the physics of galaxy and cluster formation by studying the clustering of mass, and our next work will consist of applying the halo model to use future high-precision cosmic shear surveys to this end.Journal of Cosmology and Astroparticle Physics 06/2014; 2014(08). · 5.88 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We study how parameter error forecasts for tomographic cosmic shear observations are affected by sky coverage, density of source galaxies, inclusion of cosmic microwave background experiments, simultaneous fitting of nondark energy parameters, and the parametrization of the history of the dark energy equation-of-state parameter w(z). We find tomographic shear-shear power spectra on large angular scales (l<1000) inferred from all-sky observations, in combination with Planck, can achieve σ(w0)=0.06 and σ(wa)=0.09 assuming the equation-of-state parameter is given by w(z)=w0+wa[1-a(z)] and that nine other matter content and primordial power spectrum parameters are simultaneously fit. Taking parameters other than w0, wa, and Ωm to be completely fixed by the cosmic microwave background (CMB), we find errors on w0 and wa that are only 10% and 30% better, respectively, justifying this common simplifying assumption. We also study “dark energy tomography” : reconstruction of w(z) assumed to be constant within each of five independent w bins. With smaller-scale information included by use of the Jain and Taylor ratio statistic, we find σ(wi)<0.1 for all five w bins and σ(wi)<0.02 for both w bins at z<0.8. Finally, addition of cosmic shear can also reduce errors on quantities already determined well by the CMB. We find the sum of neutrino masses can be determined to ±0.013 eV and that the primordial power spectrum power-law index, nS, as well as dns/dlnk, can be determined more than a factor of 2 better than by Planck alone. These improvements may be highly valuable since the lower bound on the sum of neutrino masses is 0.06 eV as inferred from atmospheric neutrino oscillations, and slow-roll models of inflation predict nonzero dnS/dlnk at the forecasted error levels when |nS-1|>0.04.Physical Review D 09/2004; 70(6). · 4.86 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**In this paper I generalize the halo model for the clustering of dark matter in order to produce the power spectra of the two main baryonic matter components in the Universe: stars and hot gas. As a natural extension, this can be also used to describe the clustering of all mass. According to the design of the halo model, the large-scale power spectra of the various matter components are physically connected with the distribution of each component within bound structures and thus, ultimately, with the complete set of physical processes that drive the formation of galaxies and galaxy clusters. Besides being practical for cosmological and parametric studies, the semi-analytic model presented here has also other advantages. Most importantly, it allows one to understand on physical ground what is the relative contribution of each matter component to the total clustering of mass as a function of scale, and thus it opens an interesting new window to infer the distribution of baryons through high precision cosmic shear measurements. This is particularly relevant for future wide-field photometric surveys such as Euclid. In this work the concept of the model and its uncertainties are illustrated in detail, while in a companion paper we use a set of numerical hydrodynamic simulations to show a practical application and to investigate where the model itself needs to be improved.Journal of Cosmology and Astroparticle Physics 01/2014; 2014(04). · 5.88 Impact Factor

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