The case for AGN feedback in galaxy groups (2009)
McCarthy, Ian G., Schaye, Joop, Ponman, Trevor J., Bower, Richard G., Booth, Craig M., Vecchia, Claudio Dalla, ...
[Abridged] The relatively recent insight that energy input from supermassive black holes (BHs) can have a substantial effect on the star formation rates (SFRs) of galaxies motivates us to examine its...
Galaxies at Redshift ~0.5 Around Three Closely Spaced Quasar Sightlines (2009)
Crighton, Neil H. M., Morris, Simon L., Bechtold, Jill, Crain, Robert A., Jannuzi, Buell T., Shone, Allen, ...
We examine the relationship between galaxies and the intergalactic medium at z < 1 using a group of three closely spaced background QSOs with z_em ~1 observed with the Hubble Space Telescope. Using a...
Metal-line emission from the warm-hot intergalactic medium: I. Soft X-rays (2009)
Bertone, Serena, Schaye, Joop, Vecchia, Claudio Dalla, Booth, C. M., Theuns, Tom, Wiersma, Robert P. C.
Emission lines from metals offer one of the most promising ways to detect the elusive warm-hot intergalactic medium (WHIM; 10^5 K 10^3 rho_mean) and metal-rich (Z>Z_sun) gas in and around galaxies...
The physics driving the cosmic star formation history (2009)
Schaye, Joop, Vecchia, Claudio Dalla, Booth, C. M., Wiersma, Robert P. C., Theuns, Tom, Haas, Marcel R., ...
We investigate the physics driving the cosmic star formation (SF) history using the more than fifty large, cosmological, hydrodynamical simulations that together comprise the OverWhelmingly Large...
The earliest stars and their relics in the Milky Way (2009)
Gao, L., Theuns, Tom, Frenk, C. S., Jenkins, A., Navarro, J., Springel, V., ...
We have implemented a simple model to identify the likely sites of the first stars and galaxies in the high-resolution simulations of the formation of galactic dark matter halos of the Aquarius...
The properties of satellite galaxies in simulations of galaxy formation (2009)
Okamoto, Takashi, Frenk, Carlos S., Jenkins, Adrian, Theuns, Tom
We investigate the properties of satellite galaxies in cosmological N-body/SPH simulations of galaxy formation in Milky Way-sized haloes. Because of their shallow potential wells, satellite galaxies...
Crain, Robert A., Theuns, Tom, Vecchia, Claudio Dalla, Eke, Vincent R., Frenk, Carlos S., Jenkins, Adrian, ...
[Abridged] We present the first results of hydrodynamical simulations that follow the formation of galaxies to z=0 in spherical regions of radius ~20 Mpc/h drawn from the Millennium Simulation. The...
Cosmological Radiative Transfer Comparison Project II: The Radiation-Hydrodynamic Tests (2009)
Iliev, Ilian T., Whalen, Daniel, Mellema, Garrelt, Ahn, Kyungjin, Baek, Sunghye, Gnedin, Nickolay Y., ...
The development of radiation hydrodynamical methods that are able to follow gas dynamics and radiative transfer self-consistently is key to the solution of many problems in numerical astrophysics....
Chemical enrichment in cosmological, smoothed particle hydrodynamics simulations (2009)
Wiersma, Robert P. C., Schaye, Joop, Theuns, Tom, Vecchia, Claudio Dalla, Tornatore, Luca
(Abridged) We present an implementation of stellar evolution and chemical feedback for smoothed particle hydrodynamics (SPH) simulations. We consider the timed release of individual elements by both...
Crain, Robert A., Theuns, Tom, Dalla Vecchia, Claudio, Eke, Vincent R., Frenk, Carlos S., Jenkins, Adrian, ...
We present the first results of hydrodynamical simulations that follow the formation of galaxies to the present day in nearly spherical regions of radius ~ 20 h^-1 Mpc/h drawn from the Millennium...
Galaxies at redshift ~0.5 around three closely spaced quasar sightlines (2009)
Crighton, Neil H. M., Morris, Simon L., Bechtold, Jill, Crain, Robert A., Jannuzi, Buell T., Shone, Allen, ...
We examine the relationship between galaxies and the intergalactic medium at z > 1 using a group of three closely spaced background QSOs with z_em ~1 observed with the Hubble Space Telescope. Using a...
A test suite for quantitative comparison of hydrodynamics codes in astrophysics (2008)
Tasker, Elizabeth J., Brunino, Riccardo, Mitchell, Nigel L., Michielsen, Dolf, Hopton, Stephen, Pearce, Frazer R., ...
We test four commonly used astrophysical simulation codes; Enzo, Flash, Gadget and Hydra, using a suite of numerical problems with analytic initial and final states. Situations similar to the...
Rauch, Michael, Haehnelt, Martin, Bunker, Andrew, Becker, George, Marleau, Francine, Graham, James, ...
We have conducted a long-slit search for low surface brightness Lyα emitters at redshift 2.67 < z < 3.75. A 92 hr long exposure with the ESO VLT FORS2 instrument down to a 1σ surface brightness...
Massloss of galaxies due to a UV-background (2008)
Okamoto, Takashi, Gao, Liang, Theuns, Tom
We perform cosmological hydrodynamic simulations to determine to what extent galaxies lose their gas due to photoheating from an ionizing background. We find that the characteristic mass at which...
The clustering of the first galaxy halos (2008)
Reed, Darren S., Bower, Richard, Frenk, Carlos S., Jenkins, Adrian, Theuns, Tom
We explore the clustering properties of high redshift dark matter halos, focusing on halos massive enough to host early generations of stars or galaxies at redshift 10 and greater. Halos are...
Metallicity of the intergalactic medium using pixel statistics: IV. Oxygen (2007)
Aguirre, Anthony, Dow-Hygelund, Corey, Schaye, Joop, Theuns, Tom
We have studied the abundance of oxygen in the IGM by analyzing OVI, CIV, SiIV, and HI pixel optical depths derived from a set of high-quality VLT and Keck spectra of 17 QSOs at 2.1 < z < 3.6....
Intergalactic Stars in the Fornax Cluster (2007)
We have identified ten candidate intergalactic planetary nebulae in the Fornax galaxy cluster. These objects were found during observations in 1992 and 1993 in three fields chosen well away from any...
Numerical study of energy diffusion in King models (2007)
The energy diffusion coefficients Dn (E) j h\DeltaE(E) n =\Deltati (n = 1; 2) for a system of equal mass particles moving self-consistently in an N-body realisation of a King model are computed from...
Wind accretion in binary stars -- II. Accretion rates (2007)
Smoothed particle hydrodynamics (SPH) is used to estimate accretion rates of mass, linear and angular momentum in a binary system where one component undergoes mass loss through a wind. Physical...
Rauch, Michael, Haehnelt, Martin, Bunker, Andrew, Becker, George, Marleau, Francine, Graham, James, ...
We have conducted a long slit search for low surface brightness Lyman-alpha emitters at redshift 2.67 < z < 3.75. A 92 hour long exposure with VLT/FORS2 down to a 1-sigma surface brightness detection...
Ram pressure stripping the hot gaseous halos of galaxies in groups and clusters (2007)
McCarthy, Ian G., Frenk, Carlos S., Font, Andreea S., Lacey, Cedric G., Bower, Richard G., Mitchell, Nigel L., ...
We use a large suite of carefully controlled full hydrodynamic simulations to study the ram pressure stripping of the hot gaseous halos of galaxies as they fall into massive groups and clusters. The...
Lighting the Universe with filaments (2007)
The first stars in the Universe form when chemically pristine gas heats as it falls into dark matter potential wells, cools radiatively due to the formation of molecular hydrogen, and becomes...
Neutral hydrogen in galactic fountains (2007)
Simulations of an isolated Milky Way-like galaxy, in which supernovae power a galactic fountain, reproduce the observed velocity and 21cm brightness statistics of galactic neutral hydrogen (HI). The...
Modelling Shock Heating in Cluster Mergers: I. Moving Beyond the Spherical Accretion Model (2007)
McCarthy, Ian G., Bower, Richard G., Balogh, Michael L., Voit, G. Mark, Pearce, Frazer R., Theuns, Tom, ...
(Abridged) The thermal history of the intracluster medium (ICM) is complex. Heat input from cluster mergers, AGN, and galaxy winds offsets and may even halt the cooling of the ICM. Consequently, the...
The halo mass function from the dark ages through the present day (2006)
Reed, Darren, Bower, Richard, Frenk, Carlos, Jenkins, Adrian, Theuns, Tom
We use an array of high-resolution N-body simulations to determine the mass function of dark matter haloes at redshifts 10-30. We develop a new method for compensating for the effects of finite...
ELT requirements for future observations of the Intergalactic Medium (2006)
Theuns, Tom, Srianand, Raghunathan
We summarise the science cases for an ELT that were presented in the parallel session on the intergalactic medium, and the open discussion that followed the formal presentations. Observations of the...
Numerical simulations of quasar absorbers (2005)
The physical state of the intergalactic medium can be probed in great detail with the intervening absorption systems seen in quasar spectra. The properties of the Hydrogen absorbers depend on many...
The First Generation of Star-Forming Haloes (2005)
Reed, Darren, Bower, Richard, Frenk, Carlos S., Gao, Liang, Jenkins, Adrian, Theuns, Tom, ...
We model gas cooling in high-resolution N-body simulations in order to investigate the formation of the first generation of stars. We follow a region of a LCDM universe especially selected to contain...
Confronting cosmological simulations with observations of intergalactic metals (2005)
Aguirre, Anthony, Schaye, Joop, Hernquist, Lars, Kay, Scott, Springel, Volker, Theuns, Tom
The first generation of star-forming haloes (2005)
Reed, Darren S., Bower, Richard, Frenk, Carlos S., Gao, Liang, Jenkins, Adrian, Theuns, Tom, ...
Confronting cosmological simulations with observations of intergalactic metals (2004)
Aguirre, Anthony, Schaye, Joop, Hernquist, Lars, Kay, Scott, Springel, Volker, Theuns, Tom
Using the statistics of pixel optical depths, we compare HI, CIV and CIII absorption in a set of six high quality z ~ 3-4 quasar absorption spectra to that in spectra drawn from two different...
Quenching Cluster Cooling Flows with Recurrent Hot Plasma Bubbles (2004)
Vecchia, Claudio Dalla, Bower, Richard, Theuns, Tom, Balogh, Michael, Mazzotta, Pasquale, Frenk, Carlos S.
The observed cooling rate of hot gas in clusters is much lower than that inferred from the gas density profiles. This suggests that the gas is being heated by some source. We use an adaptive-mesh...
Metallicity of the intergalactic medium using pixel statistics: III. Silicon (2003)
Aguirre, Anthony, Schaye, Joop, Kim, Tae-Sun, Theuns, Tom, Rauch, Michael, Sargent, Wallace L. W.
(Modified) We study the abundance of silicon in the intergalactic medium by analyzing the statistics of SiIV, CIV, and HI pixel optical depths in a sample of 19 high-quality quasar absorption spectra...
Schaye, Joop, Aguirre, Anthony, Kim, Tae-Sun, Theuns, Tom, Rauch, Michael, Sargent, Wallace L. W.
(Modified) We measure the distribution of carbon in the intergalactic medium as a function of redshift z and overdensity delta. Using a hydrodynamical simulation to link the H I absorption to the...
Dark energy effects on the Lyman-alpha forest (2002)
Viel, M., Matarrese, S., Theuns, Tom, Munshi, D., Wang, Yun
In quintessence models, the dark energy content of the universe is described by a slowly rolling scalar field whose pressure and energy density obey an equation of state of the form p=w $\rho$; w is...
The impact of galaxy formation on X-ray groups (2002)
Kay, Scott T., Thomas, Peter A., Theuns, Tom
Using hydrodynamical simulations of the LCDM cosmology, that include both radiative cooling and a phenomenological model for star formation and supernovae feedback, we investigate the impact of...
Numerical simulations of the intergalactic medium (2002)
The intergalactic medium at redshifts 2--6 can be studied observationally through the absorption features it produces in the spectra of background quasars. Most of the UV-absorption lines arise in...
Galactic winds in the intergalactic medium (2002)
Theuns, Tom, Viel, Matteo, Kay, Scott, Schaye, Joop, Carswell, Robert F., Tzanavaris, Panayiotis
We have performed hydrodynamical simulations to investigate the effects of galactic winds on the high-redshift (z=3) universe. Strong winds suppress the formation of low-mass galaxies significantly,...
Metallicity of the Intergalactic Medium Using Pixel Statistics: I. Method (2002)
Aguirre, Anthony, Schaye, Joop, Theuns, Tom
Studies of absorption spectra of high-z QSOs have revealed that the intergalactic medium at z ~ 2-3 is enriched to ~ 0.1%-1% solar for gas densities more than a few times the mean cosmic density, but...
Modelling the IGM and the Lyalpha forest at high redshift from the dark matter distribution (2002)
Viel, M., Matarrese, S., Mo, H. J., Theuns, Tom, Haehnelt, M. G.
A variety of approximate schemes for modelling the low-density Intergalactic Medium (IGM) in the high-redshift Universe is compared to the results of a large high-resolution hydro-dynamical...
Constraints on reionization from the thermal history of the intergalactic medium (2002)
Theuns, Tom, Schaye, Joop, Zaroubi, Saleem, Kim, Tae-Sun, Tzanavaris, Panayiotis, Carswell, Bob
The temperature of the diffuse, photo-heated intergalactic medium (IGM) depends on its reionization history because the thermal time scales are long. The widths of the hydrogen Lyman-alpha absorption...
Temperature fluctuations in the intergalactic medium (2001)
Theuns, Tom, Zaroubi, Saleem, Kim, Tae-Sun, Tzanavaris, Panayiotis, Carswell, Robert F.
The temperature of the low-density intergalactic medium is set by the balance between adiabatic cooling resulting from the expansion of the universe, and photo-heating by the UV-background. We have...
Theuns, Tom, Zaroubi, Saleem, Kim, Tae-Sun
The temperature of the low-density intergalactic medium is set by the balance between adiabatic cooling resulting from the expansion of the universe, and photo-heating by the UV-background. A sudden...
Viel, M., Matarrese, S., Mo, H. J., Haehnelt, M. G., Theuns, Tom
(abridged) We present an effective implementation of analytical calculations of the Lyalpha opacity distribution of the Intergalactic Medium (IGM) along multiple lines of sight (LOS) to distant...
Do angular momentum induced ellipticity correlations contaminate weak lensing measurements? (2001)
Natarajan, Priyamvada, Crittenden, Robert G., Pen, Ue-Li, Theuns, Tom
Alignments in the angular momentum vectors of galaxies can induce large scale correlations in their projected orientations. Such alignments arise from the tidal torques exerted on neighboring...
Crittenden, Robert G., Natarajan, Priyamvada, Pen, Ue-Li, Theuns, Tom
The distortion field defined by the ellipticities of galaxy shapes projected on the sky can be uniquely decomposed into a gradient and a curl component. If the observed ellipticities are induced by...
Spin induced galaxy alignments and their implications for weak lensing measurements (2000)
Crittenden, Robert G., Natarajan, Priyamvada, Pen, Ue-Li, Theuns, Tom
Large scale correlations in the orientations of galaxies can result from alignments in their angular momentum vectors. These alignments arise from the tidal torques exerted on neighboring...
Observational signatures of feedback in QSO absorption spectra (2000)
Theuns, Tom, Mo, H. J., Schaye, Joop
Models for the formation of galaxies and clusters of galaxies require strong feedback in order to explain the observed properties of these systems. We investigate whether such feedback has...
Lyman alpha Absorption Systems and the Intergalactic Medium (2000)
Efstathiou, George, Schaye, Joop, Theuns, Tom
The last few years have seen a dramatic improvement in our understanding of the origin of Lyman alpha absorption systems. Hydrodynamic numerical simulations of cold dark matter dominated universes...
Constraining reionization using the thermal history of the baryons (2000)
Schaye, Joop, Theuns, Tom, Rauch, Michael, Efstathiou, George, Sargent, Wallace L. W.
The thermal evolution of the intergalactic medium (IGM) depends on the reionization history of the universe. Numerical simulations indicate that the low density IGM, which is responsible for the low...
A wavelet analysis of QSO spectra (2000)
The temperature of the intergalactic medium (IGM) is an important factor in determining the line-widths of the absorption lines in the Lyman-alpha forest. We present a method to characterise the...
The thermal history of the intergalactic medium (1999)
Schaye, Joop, Theuns, Tom, Rauch, Michael, Efstathiou, George, Sargent, Wallace L. W.
At redshifts z >~ 2, most of the baryons reside in the smooth intergalactic medium which is responsible for the low column density Lyman-alpha forest. This photoheated gas follows a tight...
Broadening of QSO Lyman-alpha forest absorbers (1999)
Theuns, Tom, Schaye, Joop, Haehnelt, Martin
We investigate the dependence of QSO Lyman-alpha absorption features on the temperature of the absorbing gas and on the amplitude of the underlying dark matter fluctuations. We use high-resolution...
Measuring the equation of state of the intergalactic medium (1999)
Schaye, Joop, Theuns, Tom, Leonard, Anthony, Efstathiou, George
(Abridged) Numerical simulations indicate that the intergalactic medium (IGM) responsible for the low column density Lyman-alpha forest follows a well defined temperature-density relation. We...
Measuring the temperature of the intergalactic medium (1999)
Schaye, Joop, Theuns, Tom, Leonard, Anthony, Efstathiou, George
Numerical simulations indicate that the smooth, photoionized intergalactic medium (IGM) responsible for the low column density Lyman-alpha forest follows a well defined temperature-density relation....
Dependences of QSO Ly alpha absorption line statistics on cosmological parameters (1999)
Tom Theuns, Anthony Leonard, Joop Schaye, George Efstathiou
We have performed high-resolution hydrodynamic simulations of the Lya forest in a variety of popular cold dark matter dominated cosmologies, including a low density and a vacuum-dominated model. The...
Measuring the Equation of State of the Intergalactic Medium (1999)
Joop Schaye, Tom Theuns, Anthony Leonard, George Efstathiou
Numerical simulations indicate that the smooth, photoionized intergalactic medium (IGM) responsible for the low column density Lyff forest follows a well defined temperature-density relation, which...
Dependencies of QSO Lyman-alpha absorption line statistics on cosmological parameters (1998)
Theuns, Tom, Leonard, Anthony, Schaye, Joop, Efstathiou, George
We have performed high-resolution hydrodynamic simulations of the Lyman-alpha forest in a variety of popular cold dark matter dominated cosmologies, including a low density and a vacuum-dominated...
P3M-SPH simulations of the Lyman-alpha Forest (1998)
Theuns, Tom, Leonard, Anthony, Efstathiou, George, Pearce, F. R., Thomas, P. A.
(Abridged) We investigate the importance of several numerical artifacts such as lack of resolution on spectral properties of the Lyman alpha forest as computed from cosmological hydrodynamic...
The formalism that describes the non-linear growth of the angular momentum L of protostructures from tidal torques in a Friedmann Universe, as developed in a previous paper, is extended to include...
Intergalactic stars in the Fornax Cluster (1996)
We have identified ten candidate intergalactic planetary nebulae in the Fornax galaxy cluster. These objects were found during observations in 1992 and 1993 in three fields chosen well away from any...
The growth of the angular momentum L of protogalaxies induced by tidal torques is reconsidered within the Zel'dovich approximation. We obtain a general expression for the ensemble expectation value...
Non-linear evolution of the angular momentum of protostructures from tidal torques (1996)
We discuss the non-linear evolution of the angular momentum L acquired by protostructures, like protogalaxies and protoclusters, due to tidal interactions with the surrounding matter inhomogeneities....
Wind accretion in binary stars II. Accretion rates (1996)
Theuns, Tom, Boffin, Henri, Jorissen, Alain
Smoothed particle hydrodynamics (SPH) is used to estimate accretion rates of mass, linear and angular momentum in a binary system where one component undergoes mass loss through a wind. Physical...
Non-Linear Evolution of the Angular Momentum of Protostructures From Tidal Torques (1996)
We discuss the non-linear evolution of the angular momentum L acquired by protostructures, like protogalaxies and protoclusters, due to tidal interactions with the surrounding matter inhomogeneities....
Numerical study of energy diffusion in King models (1995)
The energy diffusion coefficients D_n(E) (n=1,2) for a system of equal mass particles moving self-consistently in an N-body realisation of a King model are computed from the probability per unit...