Extragalactic Astronomy at the Munich University Observatory (USM) and the Optical & Interpretative Astronomy group (Opinas) at MPE

The MPE Optical and Interpretative Astronomy and USM Extragalactic Astronomy USM-MPE extragalactic research group is a joint effort of the University Observatory of Munich (USM) and the Max-Planck Institute for Extraterrestical Physics. Senior group members are Prof. Ralf Bender, Prof. O. Gerhard, Prof. J. Weller, Dr. U. Hopp, Dr. R.P. Saglia, Dr. S. Seitz, Dr. Ariel Sanchez.

The group is located both at the USM (see `Extragalactic Astronomy') and at MPE.


The observational data necessary for our scientific programs come from own telescope shares (LBT, HET, Wendelstein telescope), from guaranteed time observations which come in return for our instrument buildings (FORS, SPIFFI, OmegaCAM, KMOS), from participating in carrying out public surveys (KIDS) and from applications to the ESO telescopes and the german-spanish Calar-Alto Observatory. In addition we used our Wendestein observatory in the Alps for pixellensing and other monitoring projects. In spring 2008, the 0.8m telescope was de-commissioned and we have now replaced it by a 2m-telescope with adequadate imaging and spectroscopic instrumentation. Since beginning of 2015 the telescope is in operation.

In addition, the USM-MPE extragalactic research group is designing and building imaging and spectroscopy instruments for 1-10m class telescopes, together with national and international partners. We built, e.g., the instruments for the VLT, and the low resolution spectrograph LRS for the 10m Hobby-Eberly-Telescope HET in Texas (which we share with the Universities of Texas, Penn State University, Standford and Göttingen).
Our 1-square degree imager OmegaCAM is in operation on the 2.6m VLT-survey telescope VST in Chile. We run ambitious observing programs at the VLT with our multi-IFU-infrared spectrograph KMOS and a giant optical IFU spectrograph ( VIRUS ). We further participate in the design study of the E-ELT instrument MICADO and the now accepted Cosmic Vision Survey Mission EUCLID , planned to be launched in 2020.

Finally, we also develop data reduction and analysis software. We are member of ASTROWISE, a european team (USM, Paris, Groeningen, Leiden and Naples) providing data analysis software for the OmegaCAM and any wide field data. This software is essential for all wide field imaging surveys (e.g. KIDS) carried out within the ESO community in the future. For the VIRUS project we are developing the pipeline for the automatic reduction of the integral field spectra.


The Opinas group at MPE is a member of the BOSS/SDSS3 consortium, which will obtain spectroscopic redshift for luminous red galaxies out to z=0.9. This will be used to analyse large scale clustering of galaxies as a function of redshift.
Moreover, the Opinas group at MPE is member of the PANSTARRS consortium consisting of the Institute for Astronomy (Hawaii), the Max-Planck Society, Havard University, John Hopkins University, Las Cumbres Observatory and a UK consortium (Durham, Edingburgh, Belfast). PANSTARRS carried out a multi wave band 3pi survey of the northern sky using a 7 square degree Giga-Pixel camera mounted on a 1.8 meter telescope on Haleakala (Hawaii).
PANSTARRS monitored all of M31 in each visible night with its 7 square degree camera. The PAndromeda data will allow a search for variable stars and microlensing events (6 events have been already identified, Lee et al. 2011), as well as a detailed investigation of stellar populations in the coadded data set. Recently, we have also joined the dark energy survey DES.
Finally, we participate in HETDEX , the Hobby-Eberly Telescope Dark Energy Experiment, a project designed to understand the evolutionary history of dark energy.

Some of the projects listed below are available also as MASTER projects.

Difference image movie of a 30x30 arcsec^2 area in the bulge of M31 from our WECAPP pixellensing project. Long period variables and other variable stars show up as varying black and white spots. Towards the end of the movie a microlens event is visible in the center of the field.


Please use our webpages for further information about the research activities of the extragalactic research group at USM and the optical & interpretative astronomy group at MPE. We continously offer Master projects (please contact us also by email and ask for further projects).

Project 1 (PhD or Master Project in the Dynamics Group :
``Galaxy evolution, dynamics and dark matter"

Research in the MPE Dynamics Group focusses on understanding the evolution, origin, and dynamical structure of galaxies, with particular emphasis on the Milky Way and nearby galaxies. We are a theoretical group with a strong link to observations, and long-standing experience on analytical and numerical dynamical models of galaxies. PhD and master thesis projects are offered within the following research areas (see also the links):

* Structure and origin of the bars and bulges in the Milky Way, M31, and nearby spiral galaxies;;
* Dark matter haloes, angular momentum , and mass accretion in elliptical galaxies;
* Made-to-measure particle models for galaxies;
* Tidal stripping and evolution of galaxies in clusters and the formation of intracluster light .

Ortwin Gerhard gerhard@mpe.mpg.de
Project 2 (PhD or Master Project in the OPINAS Group :
``Dark matter in dwarf elliptical galaxies"

We are performing a systematic 2-dimensional kinematic mapping of the northern nearby dwarf elliptical galaxies with our VIRUS-W instrument at the 2.7m McDonald telescope. Our goal is to measure the stellar kinematics of these objects. This will allow us to constrain the density distribution of the dark matter halos in these objects and decide whether a "cusp" (as expected in a Lambda Cold Dark Matter Universe) or a "core" (as suggested by first attempts at these measurements) is present. Moreover, we will investigate the stellar populations by mapping the strength of various absorption line indices: this will allow us to determine the age and metallicity of the galaxies and possibly their gradients. If the galaxies contain ionized gas, we will be able to measure its kinematics too and compare its motions to the stellar ones. The PhD project will involve observation trips at McDonald Observatory, data reduction and analysis and dynamical modeling.

Ralf Bender bender@mpe.mpg.de
Roberto Saglia saglia@mpe.mpg.de
Project 3 (PhD or Master Project in the OPINAS Group :
``The internal kinematics of globular clusters"

We are performing a systematic 2-dimensional kinematic mapping of the northern largest Milky Way globular clusters with our VIRUS-W instrument at the 2.7m McDonald telescope. Our goal is to constrain the internal kinematics of these objects, quantify the amount of global stellar rotation and possibly set constraints on their dark matter content. Moreover, we will investigate the stellar populations by mapping the strength of various absorption line indices: this will allow us to explore the possible gradients in age and metallicity within the globular clusters. The PhD project will involve observation trips at McDonald Observatory, data reduction and analysis and dynamical modeling.

Ralf Bender bender@mpe.mpg.de
Roberto Saglia saglia@mpe.mpg.de
Project 4 (PhD or Master Project in the OPINAS Group :
``The formation and orbital structure of disks, classical bulges, pseudo bulges and bars"

The Schwarzschild algorithm solves the collisionless Boltzman equation by superposition of orbits, which represent the space of integrals of motion. By solving for the approriate orbital weights, the method allows to determine the masses of the stars, dark matter halos and central black holes together with the distribution of stellar orbits from observed surface brightness profiles and stellar kinematical maps. Schwarzschild models have been calibrated and work well for elliptical galaxies. Disk galaxies have not been studied in detail yet. Their analysis requires extensions to the currently used implementations of Schwarzschild's method: (1) accurate solutions of the Poisson equation for very flattened disks and for bars are needed; (2) an orbit sampling scheme needs to be developed that ensures inclusion of the many more families of orbits supported by these potentials. The project is aimed to expand the existing Schwarzschild code. In a second step, the student can analyse existing observational data for disk galaxies. The main questions are (1) whether the Mbh-sigma scaling relation is different for disk galaxies with pseudo bulges and with classical bulges and (2) what the orbital structure in disk galaxies tells us about the formation history of their various components.

Jens Thomas jthomas@mpe.mpg.de
Roberto Saglia saglia@mpe.mpg.de
Project 5 (PhD or Master Project in the OPINAS Group :
``Triaxial modeling of giant ellipticals"

The masses of the stars, black holes and dark halos of elliptical galaxies thus far have mostly be obtained from dynamical models assuming axial symmetry. Giant ellipticals do not respect this symmetry and previous mass determinations of the stars and of the central black holes may be biased by up to a factor of two. This has important consequences for the slope and intrinsic scatter of global correlations like the famous Mbh-sigma relation. We have finished the development of a triaxial dynamical modelling code using the Schwarzschild orbit superposition technique (see above). Using datasets for massive elliptical galaxies that we already collected in the past, the student can reassess previous measurements of the masses of central black holes, stars and dark matter halos and investigate the implications for widely used global scaling relations.

Jens Thomas jthomas@mpe.mpg.de
Roberto Saglia saglia@mpe.mpg.de
Ralf Bender bender@mpe.mpg.de
Project 6 (PhD or Master Project in the OPINAS Group :
``The black holes, dark matter halos and IMFs of the most massive galaxies"

At the high-mass end, galaxies have extreme properties: the most massive galaxies host the most massive black holes, they populate the largest dark-matter concentrations in the universe and are believed to be dominated by an extreme population of dwarf stars. MASSIVE is a multi-wavelength survey of the 108 most massive galaxies in the local universe, aiming to investigate their detailed structure and formation histories. As part of the survey, we have collected two-dimensional stellar kinematical maps from subarcsecond scales near the center out to large radii. Dynamical modelling with Schwarzschild orbit superposition models will be used to derive dark matter halo properties and dynamical constraints on the stellar initial-mass-function (IMF). These will be compared with spectroscopic constraints on the stellar populations to study the stellar masses and the assembly histories of these extreme galaxies.

Jens Thomas jthomas@mpe.mpg.de
Ralf Bender bender@mpe.mpg.de
Project 7 (PhD or Master Project in the OPINAS Group ):
``Spectroscopic probes of the Initial Mass Function in local elliptical galaxies"

There is growing evidence that the Initial Mass Function in the central regions of elliptical galaxies might vary systematically with the mass of the systems. We are collecting optical and near infrared two-dimensional spectra of a sample of local elliptical galaxies that should allow us to investigate this issue with a large dataset. The student will derive maps of the IMF-sensitive indices, interprete them with up-to-date stellar population models and compare the results with the constraints coming from dynamics and gravitational lensing.

Alessandra Beifiori beifiori@mpe.mpg.de Roberto Saglia saglia@mpe.mpg.de Ralf Bender bender@mpe.mpg.de
Project 8 (PhD or Master Project in the OPINAS Group ):
``VIRIAL: The evolution of field passive galaxies between redshift 1 and 2"

We are collecting deep NIR spectroscopic observations of a sample of passive galaxies between redshift 1 and 2 in the field and in clusters using KMOS at the VLT. The galaxies have HST imaging available, from which stellar masses and structural parameters have been derived. When combined with the velocity dispersions and line strength indices measured from the KMOS spectra, this dataset will allow us to study the assembly and evolution of passive galaxies using the Fundamental Plane and models of stellar populations, as a function of galaxy mass and enviromental density.

Trevor Mendel jtmendel@mpe.mpg.de Roberto Saglia saglia@mpe.mpg.de Ralf Bender bender@mpe.mpg.de
Project 9 (PhD or Master Project in the OPINAS Group ):
``The quenching mechanisms of star formation in high-redshift galaxies"

We are following up a subsample of the VIRIAL passive galaxies (see above) with KMOS in the H-band to possible detect and study ionized gas emitting in the Halpha line. For the most suitable detections we plan to extend these observations with IRAM and ALMA to investigate the presence of molecular gas. This dataset will allow the student to study the mechanisms that quench star formation at redshift between 1 and 2. Are they triggered by AGN activity and/or galaxy mass? Or has the gas density become too low to allow further star formation? What is the role of environment?

Trevor Mendel jtmendel@mpe.mpg.de Roberto Saglia saglia@mpe.mpg.de Ralf Bender bender@mpe.mpg.de
Project 10 (PhD or Master Project in the OPINAS Group (USM Lensing group) ):
"Measuring weak lensing masses of clusters of galaxies with the Wendelstein 2m telescope"

The student will image SZ, Xray and optically selected clusters with the 30'x30' Wide Field Imager of the 2m telescope on Mt Wendelstein and measure their mass profiles by analyzing the weak lensing effect. The results will be used to constrain the scaling of the mass with the SZ-/Xray/Richness observables. In addition the student is expected to participate in the scientific exploitation of the DES survey regarding cluster and group weak lensing science cases.

Stella Seitz stella@usm.lmu.de
Project 11 (PhD or Master Project in the OPINAS Group (USM Lensing group) ):
``High resolution mapping of the central matter mass distribution in clusters of galaxies with strong lensing"

We will analyse the strong lensing effect of massive CLASH and Frontier Field galaxy clusters having unique HST imaging data in depth and wavelength coverage. The goal is not only to accurately measure the central 2D projected mass distribution but to in particular constrain the depth and extent of dark matter halos of cluster members and to relate their properties to their stellar light and dynamical measures of their central halo depth. By comparing the cluster galaxy members with field galaxies we'll be able to quantify the amount of tidal halo stripping they undergo when orbiting through dense cluster centers. The student will be a member of the CLASH collaboration.

Stella Seitz stella@usm.lmu.de

last update: August 2015