Empirical Models for Dark Matter Halos. I. Nonparametric Construction of Density Profiles and Comparison with Parametric Models

By D. Merritt, Alister W. Graham, B. Moore, J. Diemand, Balsa Terzic. 2005

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We use techniques from nonparametric function estimation theory to extract the density profiles, and their derivatives, from a set of N-body dark matter halos. We consider halos generated from ΛCDM simulations of gravitational clustering, as well as isolated spherical collapses. The logarithmic density slopes γ ≡ d log ρ/d log r of the ΛCDM halos are found to vary as power laws in radius, reaching values of γ ≈ -1 at the innermost resolved radii, ∼10-2rvir. This behavior is significantly different from that of broken-power-law models like the Navarro-Frenk-White (NFW) profile but similar to that of models like de Vaucouleurs's. Accordingly, we compare the N-body density profiles with various parametric models to find which provide the best fit. We consider an NFW-like model with arbitrary inner slope; Dehnen & McLaughlin's anisotropic model; Einasto's model (identical in functional form to Sérsic's model but fitted to the space density); and the density model of Prugniel & Simien that was designed to match the deprojected form of Sérsic's R1/n law. Overall, the best-fitting model to the ΛCDM halos is Einasto's, although the Prugniel-Simien and Dehnen-McLaughlin models also perform well. With regard to the spherical-collapse halos, both the Prugniel-Simien and Einasto models describe the density profiles well, with an rms scatter some 4 times smaller than that obtained with either the NFW-like model or the three-parameter Dehnen-McLaughlin model. Finally, we confirm recent claims of a systematic variation in profile shape with halo mass.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/f53cb99a92f55fd1a13b2efbd3b7a872ed3b3899

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Citations in the corpus

THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. I. THE TOTAL DENSITY OVER THREE DECADES IN RADIUS (2012, methodology): “…Université d’AixMarseille and CNRS, UMR7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13, France viations from this simple functional form (e.g., Merritt et al. 2006; Navarro et al. 2010; Gao et al. 2012), showing that halo profiles are not strictly self-similar and that the density…”
Quantifying the heart of darkness with GHALO – a multibillion particle simulation of a galactic halo (2008, unknown): “…exp(− 2/α[(r/R−2) α − 1]), (2) and the Prugniel & Simien (1997) profile ρ(r) = ρ′(r/Re) −pα exp(−bα(r/R−2) α), (3) where pα = 1 − 0.6097α + 0.05463α 2 and bα = 2/α − 1/3 + 0.009876α (for α < 2, see Merritt et al. (2006)) such that when projected one obtains a Sérsic profile (Sérsic 1963, 1968).”
The Milky Way stellar halo out to 40 kpc: squashed, broken but smooth (2011, methodology): “The Einasto profile (Einasto & Haud 1989) is often used to describe the density distribution of dark matter haloes (e.g. Grahamet al. 2006; Merritt et al. 2006; Navarro et al. 2010).”
The mass–concentration–redshift relation of cold and warm dark matter haloes (2016, background): “Improved fits are obtained with profiles whose logarithmic slopes follow simple power laws with radius, d ln ρ/d ln r ∝ r−α (e.g. Merritt et al. 2005, 2006).”
Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud (2019, methodology): “For values of n larger than 0.5, dn is defined as in Merritt et al. (2006): dn = 3n− 1/3 + 0.0079/n. (8) The use of this profile is motivated by recent observations of K-Giants (MW-X; Xue et al. 2015) and RR Lyrae (MW-H; Hernitschek et al. 2018).”
Formation of Galaxy Clusters (2012, methodology): “Subsequent simulations (Graham et al. 2006, Merritt et al. 2006, Navarro et al. 2004) showed that the Einasto (1965) profile and other similar models signed to describe deprojection of the Sérsic profile (Merritt et al. 2006) provide a more accurate description of the DM density profiles arising…”
The local dark matter density (2014, background): “This is well-fit (at the ∼ 10% level; Merritt et al. 2006; Stadel et al. 2009) by a split power law that goes as roughly r−1 in the centre and r−3 at the edge (Dubinski & Carlberg, 1991; Navarro et al., 1996b), the ‘NFW’ profile (see Figure 3b): et al., 2008).”
The mass profile and accretion history of cold dark matter haloes (2013, result): “This finding has now been verified by additional work (Merritt et al. 2005, 2006; Navarro et al. 2010; Gao et al. 2008; Hayashi & White 2008; Stadel et al. 2009; Ludlow et al. 2011) but there is no clear understanding of what breaks the similarity or what determines the value of α for a particular…”
THE UNORTHODOX ORBITS OF SUBSTRUCTURE HALOS (2008, background): “As discussed by Navarro et al (2004), Merritt et al (2005, 2006), and more recently by Gao et al (2007), ΛCDM halo density profiles are well described by αDM in the range ∼ 0.15−0.3.”
CLASH-VLT: The mass, velocity-anisotropy, and pseudo-phase-space density profiles of the z = 0.44 galaxy cluster MACS J1206.2-0847 (2013, background): “Many studies have attempted to explain the NFW-like shape of the mass density profile of cosmological halos, and why this shape is universal, even if universality is still a debated issue (e.g. Ricotti 2003; Tasitsiomi et al. 2004; Merritt et al. 2006; Ricotti et al. 2007).”