The High Energy Astrophysics group at MPE has its major scientific emphasis on studying extreme processes primarily 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.) The physical processes, including strong gravity, around black holes and other compact objects; 4.) High-energy transients (incl. Tidal Disruption Events and Gamma-ray Bursts.)
In addition to the generic projects offered for 2025, please consider the following:
Exploring Supernova Remnants in eROSITA and Multiwavelength Data
The PhD project is in the field of exploring stellar endpoints, e.g., supernova remnants and
neutron stars. The candidate shall make use of various data from current radio, optical
and high energy observatories(e.g. ASKAP, MeerKAT, XMM-Newton, Chandra, JWST, etc.).
The PhD candidate shall take an active part in the preparation of observing proposals for the
current optical, radio, and high-energy observatories and ideally shall be familiar with the
standard data analysis tools. Typically, a PhD research project develops on its own during
the course of the PhD. However, a starting point could be the identification campaign of SNR
candidates. Identified radio supernova remnants (SNRs) in the Galaxy comprise an incomplete
sample of the SNR population due to various selection effects. ROSAT performed the first All-Sky
Survey (RASS) with an imaging X-ray telescope and thus provided another window for finding SNRs
and compact objects that may reside within them. eROSITA (extended ROentgen Survey with an
Imaging Telescope Array) is the core instrument of the Russian Spektrum-Roentgen-Gamma (SRG)
mission, which was launched in Dec. 2019 and observed the X-ray sky in somewhat more than four
consecutive all-sky surveys. eROSITA has an XMM-Newton type sensitivity but an unlimited field of view
in its survey mode. This makes the instrument and its X-ray data unique, especially when searching for new
supernova remnants to explore extended objects with faint surface brightness. In the course of the PhD
research, the current identification campaign of SNR candidates shall be continued using the existing
multi-wavelength data from optical, radio, and X-ray missions. For part of the PhD research, it might
be advisable to stay at the Max-Planck Institute for Radioastronomy in Bonn.
Clusters of galaxies, located at the peaks in the cosmic density field, offer an independent and powerful probe of the growth of structure.
The properties of galaxy clusters, being sensitive to underlying cosmology, can be utilized to extract valuable information on the underlying cosmological model.
With the advent of the new eROSITA All-Sky Survey, we are on the verge of discovering more than 100,000 clusters of galaxies.
Combined with the other multi-wavelength wide-area surveys, e.g., Dark Energy Survey, eROSITA will constrain the cosmological parameters at a percent level precision at the end of its All-Sky Survey.
Complimentary to the traditional analysis methods, deep machine learning techniques provide a revolutionary way to optimally extract cosmological
parameters using the data from large-scale multi-wavelength surveys. In this Ph.D. project,
the successful candidate will learn how to analyze and process the eROSITA data of clusters of galaxies detected in the all-sky survey.
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.
Time-domain Analysis of Stars Being Disrupted by Supermassive Black
Holes with the Einstein Probe X-ray Satellite
This PhD project aims to leverage time-domain astronomy observations from the recently launched Einstein Probe X-ray satellite to probe the tidal disruption of stars in the strong gravitational fields of supermassive black holes. These Tidal Disruption Events (TDEs) and the related phenomena of Quasi-Periodic Eruptions (QPEs) allow exploring processes linked to the innermost accretion flow, accretion disk, and outflows near supermassive black holes in real time on individual sources. The project aims to develop a classifier for transients associated with SMBHs in Einstein Probe using innovative machine-learning-based algorithms and to study the resulting systematically selected samples of high-confidence X-ray TDEs. Questions that shall be addressed include: What are the commonalities and differences between X-rays and optically selected TDEs? What can we learn about the physical mechanism(s) and location(s) of the optical and X-ray emission? How do accretion disks and corona form and are destroyed? What are the properties of the population of supermassive black holes and their host galaxies that give rise to TDEs? Are QPEs linked to TDEs?
This project offers collaboration with leading European experts through extended visits and training.
The co-evolution of super-massive black holes and their host galaxies
Super-massive black holes (SMBHs) rapidly growing in active galactic
nuclei (AGN) are thought to have a crucial on their host galaxies, by
somehow stumping their long-term star formation. However, much is still
unknown about this process. One of the best ways of finding growing
SMBHs is via X-ray surveys, as the contrast between the accretion power
and stellar output of the galaxies is high, and the highly energetic
photons can penetrate any surrounding obscuring gas and dust. Through
its all-sky survey, the X-ray telescope eROSITA on board SRG discovered a clean sample of AGN of unprecedented size. This project will explore the cosmological history of black hole growth and their host galaxy through demographic studies. The project includes the study of the host galaxies of rapidly accreting super-massive black holes, including sub-populations such as over-massive black holes and the evolution over cosmic time. At the same time, the multi-wavelength emission spectrum of the central engine as a function of black hole parameters can be studied.
