Goerdt, Tobias, Read, J. I., Moore, Ben, Stadel, Joachim
Massive objects sinking within galaxies or dark matter haloes via dynamical friction will exchange momentum with central particles, ejecting them from the cusp and reducing the density of the inner...
Thin, thick and dark discs in LCDM (2008)
Read, J. I., Lake, G., Agertz, O., Debattista, Victor P.
In a LCDM cosmology, the Milky Way accretes satellites into the stellar disc. We use cosmological simulations to assess the frequency of near disc plane and higher inclination accretion events, and...
Radial density profiles of time-delay lensing galaxies (2007)
Read, J. I., Saha, P., Maccio, A. V.
We present non-parametric radial mass profiles for ten QSO strong lensing galaxies. Five of the galaxies have profiles close to $\rho(r)\propto r^{-2}$, while the rest are closer to r^{-1},...
Two strong-lensing clusters confront universal dark-matter profiles (2006)
Saha, P., Read, J. I., Williams, L. L. R.
In the galaxy clusters SSDS J1004+411 and ACO 1689, a large number of multiply-imaged background objects have recently been observed. We use these data to map the projected mass distribution in the...
Dynamical friction in constant density cores: a failure of the Chandrasekhar formula (2006)
Read, J. I., Goerdt, Tobias, Moore, Ben, Pontzen, A. P., Stadel, Joachim, Lake, George
Using analytic calculations and N-body simulations we show that in constant density (harmonic) cores, sinking satellites undergo an initial phase of very rapid (super-Chandrasekhar) dynamical...
On the formation of dwarf galaxies and stellar halos (2006)
Read, J. I., Pontzen, A. P., Viel, M.
Using analytic arguments and a suite of very high resolution (10^3 Msun per particle) cosmological hydro-dynamical simulations, we argue that high redshift, z ~ 10, M ~ 10^8 Msun halos, form the...
The internal kinematics of dwarf spheroidal galaxies (2006)
Wilkinson, M. I., Kleyna, J. T., Evans, N. W., Gilmore, G. F., Read, J. I., Koch, A., ...
The status of kinematic observations in Local Group dwarf spheroidal galaxies (dSphs) is reviewed. Various approaches to the dynamical modelling of these data are discussed and some general features...
Does the Fornax dwarf spheroidal have a central cusp or core? (2006)
Goerdt, Tobias, Moore, Ben, Read, J. I., Stadel, Joachim, Zemp, Marcel
The dark matter dominated Fornax dwarf spheroidal has five globular clusters orbiting at ~1 kpc from its centre. In a cuspy CDM halo the globulars would sink to the centre from their current...
The importance of tides for the Local Group dwarf spheroidals (2005)
Read, J. I., Wilkinson, M. I., Evans, N. Wyn, Gilmore, G., Kleyna, Jan T.
There are two main tidal effects which can act on the Local Group dwarf spheroidals (dSphs): tidal stripping and tidal shocking. Using N-body simulations, we show that tidal stripping always leads to...
The tidal stripping of satellites (2005)
Read, J. I., Wilkinson, M. I., Evans, N. W., Gilmore, G., Kleyna, Jan T.
We present an improved analytic calculation for the tidal radius of satellites and test our results against N-body simulations. The tidal radius in general depends upon four factors: the potential of...
The mass of dwarf spheroidal galaxies and the missing satellite problem (2005)
Read, J. I., Wilkinson, M. I., Evans, N. Wyn, Gilmore, G., Kleyna, Jan T.
We present the results from a suite of N-body simulations of the tidal stripping of two-component dwarf galaxies comprising some stars and dark matter. We show that recent kinematic data from the...
The baryonic mass function of galaxies (2005)
In the Big Bang about 5% of the mass that was created was in the form of normal baryonic matter (neutrons and protons). Of this about 10% ended up in galaxies in the form of stars or of gas (that can...
Tidal streams in a MOND potential: constraints from Sagittarius (2005)
We compare orbits in a thin axisymmetric disc potential in MOND to those in a thin disc plus near-spherical dark matter halo predicted by a $\Lambda$CDM cosmology. Remarkably, the amount of orbital...
Dwarf spheroidal galaxies have shallow central dark matter density profiles, low angular momentum and approximately exponential surface brightness distributions. Through N-body simulations and...
Can Supermassive Black Holes alter Cold Dark Matter cusps through accretion? (2002)
We present some simple models to determine whether or not the accretion of cold dark matter by supermassive black holes is astrophysically important. Contrary to some claims in the literature, we...