The High Energy Astrophysics group at MPE has its major scientific emphasis on the study of extreme processes mostly via X-ray observations, but also extends to other wavebands. Our main astrophysical themes are:
1.) Large scale structure, as probed hot gas in clusters and groups of galaxies, and the related cosmological implications;
2.) The cosmic history of black hole growth and its relationship to galaxy evolution;
3.)Investigating physical processes including strong gravity around black holes and other compact objects;
4) gamma-ray bursts.
Research fields for which PhD projects are offered specifically for 2020 include:
Title: Gamma-Ray Bursts in the multi-messenger era
The LIGO detection of gravitational waves from GRB 170817A as well as
the recent detection of several GRBs with Cerenkov telescopes provided
substantial new insight into the GRB physics, and re-ignited this field
of research. The thesis will deal with tests of new physical models
(including synchrotron radiation) of the prompt GRB emission and some
of the unsolved questions relating to GRB 170817A, like the emission
geometry (off-axis jets) and population studies.
Supervisor: J. Greiner
The transient X-ray sky of SRG/eROSITA
The new generation of large survey facilities provides an unprecedented window into the transient and variable heavens accross all wavelengths. At X-ray energies, the all-sky survey with the MPE-lead eROSITA instrument on-board the "Spectrum-Roentgen-Gamma" (SRG) satellite will provide the next leap in sensitivity. Reaching more than 30x deeper than its predecessor ROSAT and with in some areas of the sky up to hundreds of visits covering timescales from hours to years.
eROSITA holds the promise to uncover countless new transient and variable objects. The challenge is to find the most interesting sources, such as the tidal signatures of stars being disrupted by distant supermassive black holes, the orphan afterglows of Gamma-ray Bursts, and the elusive fast X-ray transients, among the millions of Active Galactic Nuclei, clusters of galaxies, and X-ray emitting stars that will make up the large majority of the eROSITA detections.
SRG/eROSITA was successfully launched in July 2019 and the PhD project aims at the systematic study of the transient population found in the 4-year lasting all-sky survey. This includes the X-ray analysis of individual sources and source populations as well as their multivalength characterization using optical/near-IR observations with the GROND camera at the La Silla 2.2m telescope.
Supervisors: A. Rau, K. Nandra
The local supermassive black hole population revealed by eROSITA
eROSITA will imminently conduct the most sensitive X-ray all-sky survey ever performed, which will enable the definition of new reference samples of
Active Galactic Nuclei (AGN) hosting accreting supermassive black holes. The unique hard X-ray (2-10 keV) selected sample will reveal obscured objects
undetectable in the soft X-ray, while the depth of the soft X-ray survey will yield new samples of interesting populations such as narrow-line Seyfert 1
galaxies. This project will involve the definition and characterisation of a sample or sample(s) of relatively nearby AGN, examining e.g. their obscuration
properties, Compton-thick fraction, optical spectral type, black hole masses, SEDs, host properties and variability.
The eROSITA samples will define a reference point for the X-ray luminosity function, AGN black hole mass function,
and obscuration distribution in the local Universe, as an anchor for studies of the evolution of black hole growth over cosmic time.
Supervisors: K. Nandra, T. Boller
Cluster Cosmology with eROSITA
Galaxy clusters are the largest gravitationally bound objects in the Universe and unique probes of cosmological parameters of the Universe, including mean matter density and the equation-of-state parameter of the dark energy. Large number of new clusters of galaxies will be discovered in the All sky X-ray survey with eROSITA. eROSITA's high sensitivity all sky survey will calibrate cluster masses, i.e. main ingredient of cluster cosmology, and produce stringent limits on cosmological parameters. The successful candidate will learn how to analyse and process the eROSITA data of clusters of galaxies detected in the all sky survey, establish mass scaling relations. Studying the properties of these clusters will enable significant improvements in our understanding of the formation and evolution of the most massive collapsed structures in the Universe.
Supervisors:E. Bulbul, K. Nandra
Studying Dense Ends of Filaments with eROSITA
The diffuse intergalactic medium contains the majority of the Universe’s baryons at all redshifts. Studies of absorption lines of background active galactic nuclei and quasars in UV and X-rays have only detected up to 50% of the total baryons
in low temperature filamentary gas. This shortfall is known as “the missing baryons
problem”. Tracing the extended intacluster medium in between galaxy cluster pairs is therefore of particular interest to fully understand the location of baryons, to
study the interface between the ICM and WHIM filaments, and to possibly detect the more dense ends of the WHIM filaments. The successful candidate will study the thermodynamics of outskirts of clusters of galaxies, stack X-ray observations of galaxy clusters pairs detected by the eROSITA All sky survey and measure the density, metallicity, and mass of WHIM.
Supervisor:E. Bulbul, K. Nandra
Cosmology and Structure Formation (Joint project with LMU/USM)
Studies of the internal structure of eROSITA selected galaxy clusters and groups using X-ray constraints on the intracluster medium from eROSITA, optical constraints on the galaxy populations from DES and weak lensing mass profiles derived from the DES shear and photo-z catalogs. The student leading this PhD project will be hosted at MPE and jointly supervised by :Prof. Mohr (LMU/MPE) and Dr. Jeremy Sanders (MPE).