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 2019 include:
The evolution of Super Massive Back Holes
Accreting supermassive black holes (SMBH) in active galactic nuclei (AGN) play a significant role in shaping the formation and evolution of galaxies, and of the larger structures (groups and clusters) that contain them. One of the best ways of finding growing SMBH 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. The forthcoming eROSITA instrument aboard SRG (due for launch in 2019) will perform an all-sky survey of unprecedented depth, revolutionizing the AGN census. This project will involve analysis of the early eROSITA data to provide a new measurement of the X-ray luminosity function (XLF) of AGN, to characterize the evolving population over cosmic time. It will also involve modelling to relate the XLF to the galaxy stellar mass function, and by extension the relationship between the accreting SMBH and their host galaxies.
Supervisors: K. Nandra
Lx vs redshift for eROSITA and current X-ray surveys (Curtesy: A. Merloni)
MCS J0416.1–2403, one of six clusters targeted by the Hubble Frontier Fields programme. The varying intensity of blue haze in this image is a mass map created by using new Hubble observations combined with the magnifying power of a process known as gravitational lensing. Credit: ESA/Hubble, NASA, HST Frontier Fields
Constraining the nature of dark matter using Cosmic Beasts
The most massive clusters in the Universe, also called Cosmic Beasts, will all be discovered by eROSITA. This represents a unique opportunity to study their dark matter distribution and understand their evolution processes via direct test of the Lambda-CDM cosmological paradigm.
The BUFFALO survey, an on-going treasury Hubble Space Telescope programme, was designed to test the standard cosmological paradigm, ΛCDM, by measuring the subhalo mass function of the clusters it is observing, i.e. the number of groups and sub-clusters they are made of. The student will start the thesis by analyzing the BUFFALO data, and will then combine BUFFALO observations with SuperBIT wide field high-resolution observations scheduled for 2020 (a balloon-born telescope dedicated to cluster observations). These subhalo mass function will then be compared with theoretical measurements from state-of-the-art cosmological simulations, which go beyond cold dark matter and include other dark matter candidates such as, but not limited to, warm or self-interacting dark matter particles.
Supervisors: M. Jauzac, K. Nandra
Properties of the first galaxy clusters discovered by eROSITA, a new generation X-ray observatory
Galaxy clusters are great cosmological tools and the high energy group of MPE is involved in conducting the forefront cluster survey with eROSITA space-born telescope. During its performance in the late spring 2019 verification phase, eROSITA will survey two GAMA fields with a total area of 120 square degrees. Around 500 clusters will be discovered through this survey and given the existing optical data, they will be immediately identified. We plan to calibrate the masses of those clusters using the established collaboration with HSC special survey program of Subaru telescope. The candidate will work on the analysis of X-ray data on these clusters to study multivariate scaling relations; explore the effects of selection on the cluster properties and on cosmological constraints.
Supervisor: A. Finoguenov, K. Nandra
A multi-wavelength study of supernova remnants and neutron stars
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. XMM-Newton, Chandra and Fermi).
The PhD candidate shall take active part in the preparation of observing proposals
for the current optical, radio and high-energy observatories and shall be familiar
with the common data analysis tools. Typically, a PhD research project develops by
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 on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is currently
scheduled for launch in fall 2017. In the soft band (0.5-2 keV), it will be about
30 times more sensitive than ROSAT, while in the hard band (2-8 keV) it will provide
the first ever true imaging survey of the sky. It supports to continue the previous
SNR identification campaign and to search for new supernova remnants and neutron
stars with a much higher sensitivity than was possible before. In the course of
the PhD research the current identification campaign of SNR candidates and neutron
stars shall be continued using existing multi-wavelength data from optical, radio
and X-ray missions as well as from eROSITA once the mission is up. Along that research
there will also be the possibility to look into the open questions on the internal
structure of neutron stars, on the equation of state of super-nuclear matter, on the
cooling of neutron stars as well as on their emission mechanisms for non-thermal
radiation and on particle acceleration mechanisms in supernova remnants.
Supervisor: W. Becker
Examples of SNR morphology (Curtesy: NASA CXC Photo album)
