The proposed project will exploit current and future wide-area X-ray surveys (XMM-Slew, ROSAT, XMM-XXL, eROSITA) to study the physics of Active Galactic Nuclei (AGN) feedback in different accretion modes. Comparing AGN (and their host galaxies) within different levels of activity (accretion rates ranges), we will search for signatures of different physical states (in terms of radiative efficiency, triggering mechanisms, ability of launching relativistic jets) among supermassive black holes in analogy with their stellar mass counterparts. The ongoing optical spectroscopic follow-up of X-ray selected black holes with the SDSS-IV/SPIDERS survey will deliver physical information (emission line characteristics, virial black hole masses, etc) for an unprecedentedly large fraction of these AGN, spanning a wide range of redshift, luminosity and accretion rate. Based on these datasets, most of which already in house, the proposed thesis will be focused on the following two topical questions: What is the relationship between the observed decline of the fraction of obscured AGN at high luminosity and the radiative feedback expected from quasar winds? This will be addressed by comparing optical spectroscopic signatures of outflows in SPIDERS data with the statistics of AGN obscuration and torus covering fraction derived from X-ray and NIR surveys (e.g. ROSAT, XMM and WISE) To what extent, beyond the simple Fundamental Plane scaling, do lower-luminosity AGN display analogous behaviour as stellar mass black holes (i.e. state changes, hysteresis, etc.). This will be tackled by studying the radio properties of large number of nearby X-ray selected AGN in SPIDERS and SDSS.
Supervisors: A. Merloni, A. Georgakakis, K. Nandra, M. Salvato

Accreting supermassive black holes (SMBH) in active galactic nuclei (AGN) may play a significant role in shaping the formation and evolution of the first galaxies, and their radiative output can also be important for the reionization of the Universe. One of the best ways of finding growing SMBH is using X-ray surveys, where the contrast between the accretion power and stellar output of the galaxies is high, and because the X-rays can penetrate any surrounding obscuring gas and dust. Despite this, the number of X-ray-selected AGN currently known at high redshift is very small. The aims of this project are to search for such objects in both deep and wide X-ray surveys, identify them with multiwaveband data, and ideally confirm them via longer-wavelength spectroscopy. This will provide the first census of the accretion power in the Universe during this early epoch in the formation of black holes and galaxies. The project will lead naturally into the exploitation of the eROSITA all sky survey, expected to uncover numerous high redshift AGN into the epoch of reionization at redshift larger than 6.
Supervisors: K. Nandra, A. Georgakakis, A. Merloni, M. Salvato

An external reference system suitable for autonomous spacecraft navigation can be defined by making use of the characteristic X-ray signals emitted from pulsars. Their periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board the spacecraft with predicted pulse arrivals at a reference location, the spacecraft position and velocity can be determined autonomously and with high accuracy everywhere in the solar system and beyond. The unique properties of pulsars make clear already today that such a navigation system will have its application in future astronautics. In the course of the PhD research the currently preformed simulation of navigating a spacecraft by pulsar signals shall be continued towards the realistic design of a real navigator.
Supervisor: W. Becker

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 spring 2016. 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 pulsars 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.
Supervisor: W. Becker

Although XMM has two serendipitous surveys of galaxy clusters (XCLASS and XCS), there has only been one major serendipitous cluster survey (CHAMP). Surveys of galaxy clusters are important to examine cosmology, using clusters as tracers of mass, or for understanding the astrophysics of clusters. Chandra has a smaller field of view and lower sensitivity compared to XMM, but has a better ability to remove contaminating point sources. This project will be to develop automated pipelines for the detection of extended objects or clusters in Chandra observations and apply them to the Chandra archive. MPE (such as GROND) and international facilities will be used to confirm candidates as clusters. The sample will be applied to examining cosmology and cluster physics.
Supervisors: J. Sanders, K. Nandra

Both Active Galactic Nuclei (AGN) and Galactic Black Holes (GBH) show broad reflection Fe K lines. These lines are broadened by the movement of the material of the accretion disc and they are shaped by special and general relativistic effects, such as: Doppler shifts, gravitational red-shift, and light bending. Thus, the study of the shape and variability of broad Fe K lines provide us with an excellent tool to measure the geometry and dynamics of the matter distribution down to the last stable orbit of the accretion disc and to even constrain the BH spin. This exercise is complicated by the possible presence of ionised gas along the line of sight that can produce features mimicking the broad Fe K line shape. Therefore, in order to safely extract information on the innermost regions around the BHs through the reflected Fe K line, the impact of the absorbing material for each source has to be carefully diagnosed. This is possible with deep exposures and spectral variability studies of the brightest AGN and GBH observed with the highest effective area X-ray instruments.
Supervisors:G. Ponti, K. Nandra