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The radial escape-velocity profile of galaxy clusters has been suggested to be a promising and competitive tool for constraining mass profiles and cosmological parameters in an accelerating universe. However, the observed line-of-sight escape profile is known to be suppressed compared to the underlying radial (or tangential) escape profile. Past work has suggested that velocity anisotropy in the phase-space data is the root cause. Instead we find that the observed suppression is from the statistical under-sampling of the phase-spaces and that the radial escape edge can be accurately inferred from projected data. We build an analytical model for this suppression which only requires the number of observed galaxies $N$ in the phase-space data within the sky-projected range $0.3 le r/R_{200,critical} le 1$. The suppression function is an inverse power-law $Z_v = 1 + (N_0/N)^lambda$ with $N_0 = 14.205$ and $lambda= 0.467$. We test our model with N-body simulations, using dark matter particles, sub-halos, and semi-analytic galaxies as the phase-space tracers and find percent level accuracy and precision. We show that this suppression function is independent of cluster mass, cosmology, and velocity anisotropy.
When clusters of galaxies are viewed in projection, one cannot avoid picking up foreground/background interlopers (FBIs), that lie within the virial cone (VC), but outside the virial sphere. Structural & kinematic deprojection equations are not known
(Abridged) We have derived detailed R band luminosity profiles and structural parameters for a total of 430 brightest cluster galaxies (BCGs), down to a limiting surface brightness of 24.5 mag/arcsec^2. Light profiles were initially fitted with a Ser
Simulations have indicated that most of the escaped Lyman continuum photons escape through a minority of solid angles with near complete transparency, with the remaining majority of the solid angles largely opaque, resulting in a very broad and skewe
We study a sample of 207 nearby galaxy groups and clusters observed with XMM-Newton. Key aspects of this sample include the large size, the high data quality, and the large diversity of cluster dynamical states. We determine the overall metallicity w
We study the evolution of the cross-correlation between voids and the mass density field - i.e. of void profiles. We show that approaches based on the spherical model alone miss an important contribution to the evolution on large scales of most inter