Bjoern Malte Schaefer

The Growth of Structure in Interacting Dark Energy Models (2009)

Caldera-Cabral, Gabriela, Maartens, Roy, Schaefer, Bjoern Malte

If dark energy interacts with dark matter, there is a change in the background evolution of the universe, since the dark matter density no longer evolves as a^{-3}. In addition, the non-gravitational...

Implications of bias evolution on measurements of the integrated Sachs-Wolfe effect: errors and biases in parameter estimation (2009)

Schaefer, Bjoern Malte, Douspis, Marian, Aghanim, Nabila

The subject of this paper is a quantification of the impact of uncertainties in bias and bias evolution on the interpretation of measurements of the integrated Sachs-Wolfe effect, in particular on...

Constraints on early dark energy from CMB lensing and weak lensing tomography (2009)

Hollenstein, Lukas, Sapone, Domenico, Crittenden, Robert, Schaefer, Bjoern Malte

Dark energy can be studied by its influence on the expansion of the Universe as well as on the growth history of the large-scale structure. In this paper, we follow the growth of the cosmic density...

Review: galactic angular momenta and angular momentum correlations in the cosmological large-scale structure (2008)

Schaefer, Bjoern Malte

I review the theory of angular momentum acquisition of galaxies by tidal torquing, the resulting angular momentum distribution, the angular momentum correlation function and discuss the implications...

Twist and Turn: Weak Lensing Image Distortions to Second Order (2008)

Bacon, David J., Schaefer, Bjoern Malte

We account for all the image distortions relevant to weak gravitational lensing to second order. Besides the familiar shear, convergence, rotation and flexions, we find two new image distortions, the...

Constraints on the decay of dark matter to dark energy from weak lensing bispectrum tomography (2008)

Schaefer, Bjoern Malte, Caldera-Cabral, Gabriela Alejandra, Maartens, Roy

We consider a phenomenological model for a coupling between the dark matter and dark energy fluids and investigate the sensitivity of a weak lensing measurement for constraining the size of this...

The integrated Sachs-Wolfe effect in cosmologies with coupled dark matter and dark energy (2008)

Schaefer, Bjoern Malte

The subject of this paper is the derivation of the integrated Sachs-Wolfe (iSW) effect in cosmologies with coupled dark matter and dark energy fluids. These couplings influence the iSW-effect in...

Mixed three-point correlation functions of the nonlinear integrated Sachs-Wolfe effect and their detectability (2008)

Schaefer, Bjoern Malte

In this paper I investigate the family of mixed three-point correlation functions , q=0,1,2, between the integrated Sachs-Wolfe (iSW) temperature perturbation tau and the galaxy overdensity gamma as...

Spherical collapse in modified gravity with the Birkhoff-theorem (2007)

Schaefer, Bjoern Malte, Koyama, Kazuya

We study structure formation in a phenomenological model of modified gravity which interpolates between LambdaCDM and phenomenological DGP-gravity. Generalisation of spherical collapse by using the...

Detecting Sunyaev-Zel'dovich clusters with PLANCK: III. Properties of the expected SZ-cluster sample (2006)

Schaefer, Bjoern Malte, Bartelmann, Matthias

The PLANCK-mission is the most sensitive all-sky submillimetric mission currently being planned and prepared. Special emphasis is given to the observation of clusters of galaxies by their thermal...

Weak lensing in the second post-Newtonian approximation: Gravitomagnetic potentials and the integrated Sachs-Wolfe effect (2005)

Schaefer, Bjoern Malte, Bartelmann, Matthias

Dark matter currents in the large-scale structure give rise to gravitomagnetic terms in the metric, which affect the light propagation. Corrections to the weak lensing power spectrum due to these...

Coded mask imaging of extended sources with Gaussian random fields (2004)

Schaefer, Bjoern Malte

A novel method for generating coded mask patterns based on Gaussian random fields (GRF) is proposed. In contrast to traditional algorithms based on cyclic difference sets, it is possible to construct...

Detecting Sunyaev-Zel'dovich clusters with PLANCK: I. Construction of all-sky thermal and kinetic SZ-maps (2004)

Schaefer, Bjoern Malte, Pfrommer, Christoph, Bartelmann, Matthias, Springel, Volker, Hernquist, Lars

All-sky thermal and kinetic Sunyaev-Zel'dovich (SZ) maps are presented for assessing how well the PLANCK-mission can find and characterise clusters of galaxies, especially in the presence of primary...

Detecting Sunyaev-Zel'dovich clusters with PLANCK: II. Foreground components and optimised filtering schemes (2004)

Schaefer, Bjoern Malte, Pfrommer, Christoph, Hell, Reinhard, Bartelmann, Matthias

The PLANCK mission is the most sensitive all-sky CMB experiment currently planned. The High Frequency Instrument (HFI) will be especially suited for observing clusters of galaxies by their thermal...

Redshift estimation of clusters by wavelet decomposition of their Sunyaev-Zel'dovich morphology (2003)

Schaefer, Bjoern Malte, Pfrommer, Christoph, Zaroubi, Saleem

A method for estimating redshifts of galaxy clusters based solely on resolved Sunyaev-Zel'dovich (SZ) images is proposed. Given a high resolution SZ cluster image (with FWHM of approx. 1 arcmin), the...

A Fourier-Based Algorithm for Modelling Aberrations in HETE-2's Imaging System (2003)

Schaefer, Bjoern Malte, Kawai, Nobuyuki

The High-Energy Transient Explorer (HETE-2), launched in October 2000, is a satellite experiment dedicated to the study of gamma-ray bursts in a very wide energy range from soft X-ray to gamma-ray...