Masters Projects in the MPE/HE group |
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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.
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The substructure mass function sampled by galaxies in clusters How substructures grow within clusters of galaxies is largely dependent on the properties of dark matter. Studying how galaxies populate the eROSITA clusters should enhance our understanding on what dark matter is. (w/ Dr. Johan Comparat) Constraining Self-Interaction Cross-Section of Dark Matter Numerical simulations predict that after a merger reaches equilibrium, self-interacting dark matter (SIDM) leaves imprints on the distribution of baryonic and dark matter through sloshing. When combined, the accurate ICM centorids provided from eROSITA observations and the locations of the BCG and dark matter halo of massive relaxed clusters will allow us to test cold dark matter scnerio (w/ Dr. Esra Bulbul). The substructure mass function sampled by galaxies in clusters How substructures grow within clusters of galaxies is largely dependent on the properties of dark matter. Studying how galaxies populate the eROSITA clusters will enhance our understanding on what dark matter is (w/ Dr. Johan Comparat) The first eROSITA detected supercluster: major merger, warm-hot intergalactic medium, and energetic phenomena Superclusters of galaxies are among the largest products of structure formation. They are so large and massive that they haven’t finished forming yet, and are still collapsing under the action of their own gravity, mainly caused by their large dark matter content. Their formation and evolution is highly connected to the evolution of the our Universe, and therefore can be used to test our knowledge regarding cosmological models, to probe the nature of dark matter, and study highly energetic phenomena that take place during cluster merger, particularly frequent in superclusters. In this project we will study the first supercluster discovered by eROSITA, making use of five XMM-Newton dedicated observation to resolve the triple merger in the northern part of the system, a careful attempt detection of the warm-hot intergalactic medium in the region connecting the clusters that form the supercluster, and detailed thermodynamic analysis of the properties of the supercluster members (w/ Dr. Vittorio Ghirardinin). Revealing the physics in clusters of galaxies Images of galaxy clusters show a range of physical processes taking place. These include feedback by active galactic nuclei and mergers. This project is to develop optimal filters for revealing structure in X-ray images of clusters of galaxies to interpret the physical processes taking place (w/ Dr. Jeremy Sanders). Cool cores in eROSITA eFEDS Cool cores in galaxy clusters are sensitive to the physical processes taking place in them, such as mergers and AGN feedback. We plan to measure the fraction of cool cores in the eROSITA eFEDS survey, and relate this to the dynamical state and activity of AGN in the clusters (w/ Dr. Jeremy Sanders). Searching for Axion-like Particles with eROSITA This project is about searching for one potential dark matter candidate, axion-like particles (ALPs) which interact with photons in background magnetic fields. An excellent opportunity to look for ALPs is by studying X-ray spectra of point-sources in and behind galaxy clusters. We will prepare a catalogue of such sources observed with eROSITA and then search for ALPs with standard statistical and modern machine learning techniques (w/ Dr. Sven Krippendorf). Machine Learning Cluster Properties Properties of galaxy clusters such as their masses provide vital insights into cosmological parameters. This project seeks to improve the inference of these morphological parameters in eROSITA cluster observations using Machine Learning. Based on such improved measurements, a subsequent aspect can be the inference of scaling relations using Machine Learning (w/ Dr. Sven Krippendorf). Measuring accurate redshifts of eROSITA galaxy clusters with SDSS-5 spectroscopy To turn the eROSITA photometry into a three dimensional map of the large scale structure, we measure their redshifts. The measurement of a large number eROSITA cluster galaxies' redshifts with the Sloan Digital Sky Survey 5, which already started to observe our targets. The master student will be involved in two large scientific collaborations (eROSITA and SDSS-5) to participate in the effort of obtaining redshift measurements, he stellar masses and velocity dispersion from the spectra to then study scaling relations (w/ Dr. Johan Comparat). Reconstructing 3D galaxy cluster shapes using eROSITA By looking at the images of a set of objects, their distribution of 3D shapes can be inferred. eROSITA is producing the largest number of X-ray images of galaxy clusters in existence. These images are sensitive to the multi-million degree plasma which dominates the baryonic material in galaxy clusters. This project is to measure the distribution of the shapes of the X-ray emitting material in galaxy clusters, e.g. aspect ratios, and to compare to theoretical expectations (w/ Dr. Jeremy Sanders). Reconstructing the appearance of galaxy clusters X-ray images of galaxy clusters are often extremely photon-limited. For example, the Chandra X-ray telescope has extremely high spatial resolution, but this cannot be taken advantage of in many observations as it detects so few X-ray photons. However, there may be information within these photon-starved images which is hard to reveal using standard image processing techniques. This project is to investigate whether it is possible to use deep-learning techniques to reconstruct better the true appearance of galaxy clusters. We can take the simulated appearance of a set of simulated galaxy clusters in order to train neural networks to apply to real clusters (w/ Dr. Jeremy Sanders). Revealing the physics in clusters of galaxies Images of galaxy clusters show a range of physical processes taking place. These include feedback by active galactic nuclei and mergers. This project is to develop optimal filters for revealing structure in X-ray images of clusters of galaxies to interpret the physical processes taking place (w/ Dr. Jeremy Sanders). AGN PHYSICS and EVOLUTION (contact Dr. Mara Salvato) How clumpy is the environment of supermassive black holes? Explore the physics of photons as they interact with clumpy and smooth ideas of the inner-most light year of galaxies. These are tested with existing, high-resolution X-ray spectra. (w/ Dr. Johannes Buchner) Identifying buried AGN in eROSITA observations Use machine learning to investigate how we can use eROSITA and multi-wavelength data to best identify interesting sources, including growing super-massive black holes buried in gas and dust.Short description (w/ Dr. Johannes Buchner) Opening the X-ray spectral-timing Universe? The project will explore new analysis techniques for X-ray color changes, important to understand accretion onto supermassive black holes, the origin of the soft excess and relativistic reflection. The techniques will be applied to eROSITA light curves and archival XMM data (w/ Dr. Johannes Buchner). Improving our ability to do correct multi-wavelength associations ? Currently, the cross-identification of sources in the X-ray, optical and infrared sky relies primarily on their separation. Secondarily, psical properties can be used to reject unlikely counterparts. The next step is to rule out unlikely combinations, for example X-ray to infrared flux ratios and X-ray hardness. This project will look at machine learning extensions to the NWAY code (Salvato, Buchner et al 2018) which will strengthen the search and identification of eROSITA sources (w/ Dr. Johannes Buchner and Dr. Mara Salvato). Environmental study of High-z AGN ? We expect that high-z AGN are located in overdense regions but also due to the small sample of object and the lack of multiwavelength data for the study of the envoronment. We now have a sizable sample and the multiwavelgnth photometry for testing the ipothesis. (w/ Dr. Mara Salvato ). AGN Physics from spectroscopy (more than one project) The project focusses on extraction of physical host/AGN parametrs and the study of their correlation as a function of X-ray properties. For the project proprietary data on a spectroscopic sample of many thousand AGN detected by eROSITA will be used. (Tasks: Data analysis and Machine Learning applied to big data) (w/ Dr. Mara Salvato) Photometric redshift for AGN via Machine Learning Exploratory: using multiwavelength photometry and images for a huge spectroscopic sample of AGN, develop and algorithm for the computation of Photometric Redshifts of AGN using Machine Learning (w/ Dr. Mara Salvato) THE TRANSIENT SKY (contact Dr. Arne Rau) eROSITA X-ray properties of optical transients Optical wide-angle imaging surveys generate a flood of transient and variable sources, associated with a variety of phenoma. These include the signatures of stars being disrupted in the gravitational potential of super massive black holes, exploding stars, and a broad range of accretion events on stellar mass black holes and super massive black holes. This project aims at understanding the high-energy properties of these source by systematically studying the eROSITA all-sky survey X-ray data of a large sample of events. (tasks: selection of sample from catalogues provided by optical imaging surveys, X-ray data analysis, interpretation, optical/near-IR follow-up) (w/ Dr. Arne Rau) Optical/NIR Studies of eROSITA discovered Stars Being Disrupted by Supermassive Black Holes When a star gets to close to a supermassive black hole, it can be torn apart by the strong gravitational forces. This tidal disruption, and the subsequent fall of the stellar debris on to the supermassive black hole, can lead to a bright and long-lived new source. The X-ray band, as probed by the All-sky Survey of MPE's eROSITA instrument onboard the SRG mission, is ideally suited to discover these events. In the ~2.5yr of eROISTA observations performed so far, >150 candidates for such events have been found. In order to verify their nature, measure their distances, probe their environments and their evolution, we are conducting extensive observing campaigns with optical telescopes. This project aims at analysing existing optical/NIR imaging data from MPE's GROND camera mounted at the 2.2m telescope at the La Silla Observatory (Chile) and optical spectroscopic data obtained with telescopes in Chile, Australia, and Hawaii. (w/ Dr. Arne Rau) Optical & near-IR properties of eROSITA TDEs using GROND observations (w/ Dr. Arne Rau) The aim of this project is to study the optical and near-infrared properties of eROSITA-selected Tidal Disruption Events (transient flares originating from stars that are disrupted near super-massive black holes). The data that will be used in this project come from our simultaneous 7-channel imager GROND mounted at the 2.2m telescope at La Silla, Chile. The project includes the data reduction and analysis of existing GROND data as well their interpretation and theoretical light curve modelling. In addition, direct involvement in obtaining new GROND observations will be offered (tasks: optical/NIR data reduction and analysis, modelling of lightcurves, interpretation, organisation and execution of observations). (w\ Dr. Arne Rau). Transients with the Athena Wide-Field Imager - A forecast Athena is the next large X-ray observatory in the ESA space program. When it will be launched in the early 2030ies Athena will provide unprecedented capabilities in sensitive wide-field imaging and high-resolution spectroscopy. The MPE high-energy group is leading the development of the Wide Field Imager instrument (WFI). The aim of this project is to provide a forecast of its capabilities to detect transients ranging from Tidal Disruption Events and mergers of supermassive black holes to Fast X-ray transients, a newly emerging class of events potentially assiciated to mergers of neutron stars. The study will performed with the end-to-end simulator SIXTE, which provides the capabilities to simulate observations in all details as if they were taking with the real satellite. The outcome of this study will help shaping the requirements for Athena. (tasks: end-to-end simulations of X-ray observations with SIXTE, estimation of detection rates based on realistic source population input models) (w/ Dr. Arne Rau) THE NEARBY UNIVERSE (contact Dr. Frank Haberl ) Colliding wind binaries are massive stars in binary systems that can generate X-ray emission in the region between the two stars where the stellar winds collide. A handful of these objects have been identified from XMM-Newton data using X-ray and optical colours. The sample also includes a rare class of SG B[e] system in the LMC. The project aims at performing a systematic study of colliding wind binaries in the Magellanic Clouds using X-ray (XMM and eROSITA), optical and infrared data and understanding their X-ray properties. (w/ Dr. Chandreyee Maitra and Dr. Frank Haberl) Uncovering pulsar wind nebulae (PWNe) and rotation powered pulsars in the Magellanic Clouds using radio and high resolution Chandra observations The project will analyse the deep Chandra observation of DEM S5 available which shows evidence of a compact X-ray PWN for the first time. DEM S5 is a probable bow-shock PWN in the SMC which could not be resolved in x-rays with the earlier XMM observations. It is the first extragalactic bow-shock PWN to be discovered.(w/ Dr. Chandreyee Maitra and Dr. Frank Haberl) High resolution X-ray spectroscopy of SN1987A using XMM-Newton RGS data the aim of the project is to search for faint emission lines in combined RGS spectra and investigate line variability between different epochs.(w/ Dr. Chandreyee Maitra and Dr. Frank Haberl) AGN population behind the Large and Small Magellanic Clouds? Many new AGN candidates in the LMC have been identified using XMM+ALLWISE colours and also from latest radio surveys of the Magellanic Clouds: the project is aimed to probe the characteristics and long term variability of these objects using combining XMM and, possibly, eROSITA data . Another goal is to perform optical spectroscopic follow-ups to confirm and identify their exact nature. (w/ Dr. Chandreyeee Maitra) X-ray background studies as a function of solar activity? Short description (w/ Dr. Michael Freyberg) |