TY - UNPB

T1 - Hierarchical clustering, the universal density profile, and the mass-temperature scaling law of galaxy clusters

AU - Tittley, Eric R.

AU - Couchman, H. M. P.

PY - 1999/11/1

Y1 - 1999/11/1

N2 - The significance of hierarchical clustering on the density profile and
mass-temperature scaling relation for galaxy clusters is examined using
hydrodynamic N-body simulations. Clusters formed hierarchically are
compared with clusters formed with the initial density fluctuations on
sub-cluster scales removed via smoothing. The universal profile, as
described by Navarro, Frenk, and White, is not a by-product of
hierarchical clustering. It is found to fit the mean profiles of
clusters formed both hierarchically and otherwise. The Hernquist profile
is also found to fit the data well. The characteristic radius, r_s,
moves outward from 0.1 R_200 to 0.2 R_200 when the initial substructure
is eliminated. Interior to r_s, rho_DM is proportional to r^-1.8,
regardless of initial smoothing. Exterior to this radius, the profile is
marginally shallower in the non-hierarchical case, with rho_DM
proportional to r^-2.4 compared with rho_DM proportional to r^-2.7. The
mass-temperature scaling relation maintains the form T proportional to
M^2/3, regardless of cluster formation method. The normalisation varies
at the 20% level, which is at the level of the intrinsic scatter, with
the non-hierarchical simulations producing the cooler clusters.

AB - The significance of hierarchical clustering on the density profile and
mass-temperature scaling relation for galaxy clusters is examined using
hydrodynamic N-body simulations. Clusters formed hierarchically are
compared with clusters formed with the initial density fluctuations on
sub-cluster scales removed via smoothing. The universal profile, as
described by Navarro, Frenk, and White, is not a by-product of
hierarchical clustering. It is found to fit the mean profiles of
clusters formed both hierarchically and otherwise. The Hernquist profile
is also found to fit the data well. The characteristic radius, r_s,
moves outward from 0.1 R_200 to 0.2 R_200 when the initial substructure
is eliminated. Interior to r_s, rho_DM is proportional to r^-1.8,
regardless of initial smoothing. Exterior to this radius, the profile is
marginally shallower in the non-hierarchical case, with rho_DM
proportional to r^-2.4 compared with rho_DM proportional to r^-2.7. The
mass-temperature scaling relation maintains the form T proportional to
M^2/3, regardless of cluster formation method. The normalisation varies
at the 20% level, which is at the level of the intrinsic scatter, with
the non-hierarchical simulations producing the cooler clusters.

KW - Astrophysics

M3 - Working paper

SP - 11365

BT - Hierarchical clustering, the universal density profile, and the mass-temperature scaling law of galaxy clusters

PB - ArXiv

ER -