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Max-Planck-Institut für extraterrestrische Physik |
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 MPE Opt. & Int. Astronomy
 Research
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| Opt. & Int. Astronomy
Personnel Research Black Holes Galaxy Evolution Dark Matter Dark Energy Planets Instruments Projects Collaborations Dynamics Group TMoX Group Publications Lectures Seminars Master- and PhD-Theses Internal Pages  |
Deutsche Version
1. The evolution of galaxiesThe study of the galaxy properties as a function of redshifts is an obvious observational tool to constrain galaxy formation and evolution models. Studying cluster early-type galaxies up to redshift 0.6 points to high-formation redshift and passive evolution, with internal gradients of the stellar populations being caused by metallicity rather than age. Once the evolution of their stellar populations is calibrated, early-type galaxies can be used as ``standard candles'' to derive the parameters of the Universe, providing results compatible with the (more precise) Supernovae studies. In contrast, massive spiral galaxies are very similar to local ones up to redshift ~ 1, while strong evolution is observed in low-mass disk objects. more
2. Galactic DynamicsThe dynamics of galaxies not only provide fundamental information on their origin and evolution, but also has many challenging and interesting aspects by itself. Our research on galaxy dynamics focusses on several key topics:
the orbital structure in the outer halos of elliptical galaxies,
where dynamical timescales are long and the imprint of formation
mechanisms are preserved more strongly. We are involved in the
_PN.S project_ to measure the kinematics in the halos with planetary
nebula velocities out to many effective radii, and model them to learn
about the halo dynamics;
modeling the dark matter distribution in elliptical galaxies
(see _here_);
modeling bulges and massive ellipticals to constrain the masses of
their nuclear black holes (see _here_);warped disks in the vicinity of black holes, equilibria and dynamically evolving disks, see _here_;
the NMAGIC
project: constructing particle models of galaxies using the
chi-squared made-to-measure algorithm, based on various
observational data. We are using this new method
for modeling
dark matter halos, and we are continuing to improve it to make
use of its general applicability.
Early-type galaxy halos kinematics. Using planetary nebulae radial
velocity measurements in early-type galaxies we are able to probe the
two-dimensional kinematics out to 5-10 effective radii, extending much
further out the information available only with absorption line
kinematics (usually confined within the central 2 effective radii).
See here.
3. Dark MatterWe are part of the the SFB 375 on Astroparticle Physics.
3.2 The peculiar velocity flows of the local universePeculiar velocities are deviations from the smooth Hubble flow of the expansion of the Universe. They are generated by the inhomogeneities of the matter distribution and can be detected by measuring at the same time the distance and the redshift of galaxies. They test dynamically the predictions of the Cold Dark Matter models of the evolution of the large scale structure in the local Universe. In the context of the recently completed EFAR project the distances of 50 Clusters of Galaxies in the Corona-Borealis and Pisces-Cetus superclusters using the Fundamental Plane distance estimator were measured. The resulting mean bulk motions within 100 Mpc are small, compatible with the predictions of ΛCDM. They rule out the detections of large bulk motions claimed by other surveys.
3.3 Gravitational lensingGravitational lensing is sensitive to all matter inhomogeneities along the line of sight, irrespective of their nature (baryonic or dark matter) and their dynamical state (relaxed or merging systems). Also, analysis of the lensing effect does not require any assumptions about the symmetry of the interveining mass distributions. Therefore, the gravitational lens effect can be used to investigate mass distributions on all scales and almost any distance along the line of sight. more
4. Dark EnergyWe are designing surveys to measure the power spectrum of the galaxy distributions at high (z = 1-2) redshifts as a tool to constrain the redshift evolution of the equation of state of Dark Energy.
5. Black HolesWe are part of the Priority Program 1177, "Witnesses of Cosmic History: Formation and evolution of black holes and their environment". Studies of the dynamics of stars and gas in the nuclei of nearby galaxies have established that all galaxies with a massive (classical) bulge component contain a central supermassive black hole. The mass of the black hole is closely correlated with the bulge luminosity and the bulge velocity dispersion. We measure stellar velocities in the nuclei of galaxies with SINFONI, and model them to constrain the masses of the nuclear black holes, and focus on the question whether galaxies with small and large sigma fall onto the black hole mass sigma relation.
6. Stellar PopulationsThe evolutionary population synthesis (EPS) is the technique to model the spectrophotometric properties of stellar populations, that uses the knowledge of stellar evolution. This approach was pioneered by B. Tinsley in a series of fundamental papers, that provide the basic concepts still used in present-day computations. The models are used to determine ages, element abundances, stellar masses, stellar mass functions, etc., of those stellar populations that are not resolvable in single stars, like galaxies and extra-galactic globular clusters. more
6.2 Dwarf GalaxiesNearby dwarf galaxies allow to resolve their stellar population into individual stars. This is especially true for images obtained with the optical and near infrared cameras aboard the Hubble Spece telescope. Doing deep multi-band photometry of the individual stars of those dwarf galaxies allows to reconstruct the star formation history of the host galaxies when comparing the observed color magnitude diagrams with simulated ones based on stellar evolutionary codes. more
6.3 Elliptical Galaxies and Globular ClustersThe most direct way to constrain the formation and evolution of galaxies certainly is to trace back their evolution with redshift. The price to be paid, however, is that high-redshift data naturally have lower quality and are therefore more difficult to interpret. A clear complication is the so-called progenitor bias, which implies that galaxies observed at low and high redshift are not necessarily drawn from the same sample (van Dokkum et al. 2000). The alternative approach is the detailed investigation of the stellar populations in local galaxies, which has been pioneered by analyzing slopes and scatter of color-magnitude and scaling relations of early-type galaxies, followed by a number of detailed studies of absorption line indices. We call this the 'archaeology approach'. The confrontation with predictions from models of galaxy formation is certainly most meaningful, when the two approaches, the mining of the high-redshift universe and the archaeology of local galaxies set consistent constraints. more
7. Search for extrasolar planets.Our extrasolar planet activities started in July 2002, when we monitored photometrically ten galactic high star-density fields with the Wendelstein Telescope, to search for planets with the transit method. This project allowed us to develop the necessary expertise for the RoPACS , the PanPlanets and the OmegaTrans projects. Find more about our photometric and spectroscopic searches and follow-ups here.
last update: 10/2005, editor of this page: Roberto Philip Saglia
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Weak Lensing