Recruitment

We will be recruiting 11 PhD students across Europe to work on a range of projects related to the study of supermassive black holes. The PhD studentships are anticipated to start in Autumn 2025. Information about the 11 positions and their host institutes are listed below. Application details and deadlines are different for each host.

National Observatory of Athens, Greece

Project 1, The panchromatic flux variability properties of Quasars: use large samples of distant QSOs with X-ray multi-epoch observations to quantify the statistical properties (power-spectral density) of their X-ray flux variability. This result will be combined with both independent estimates of the ultraviolet/optical flux variability of QSOs and new physically-motivated simulations of the dynamic accretion flow to place new constraints on the physical scale of the X-ray emitting corona relative to the inner accretion disk (dominating at ultraviolet and optical wavelengths) as a function of black hole mass and Eddington ratio. For more details and application deadlines please visit the EURAXESS post.

University of Crete, Greece

Project 2, Energy dependent X-ray power spectral density: study of the X-ray power spectrum (PSD), as a function of energy, in Active Galactic Nuclei (AGN). It will be based on the use of archival data, from past and current X-ray missions, for a large number of AGN. The main objective is to detrmine the PSD over the longest possible time scales, and characterize the dependence of the PSD properties (like the low and high frequency slopes, normalization and characteristic bending frequencies) on energy and on BH mass and accretion rate. This project aims to present the most complete variability atlas of AGN in the 0.3-20 keV band in AGN, and pt constrains to theoretical models that seek to explain the X-ray variations in these objects. For more details and application deadlines please visit the EURAXESS post.

Project 3, The X-ray reverberation time-lags study in AGN: study of the X-ray time-lags, as a function of frequency, at as many energy bands as possible, using archival data, from past and current X-ray missions, for a large number of Active Galactic Nuclei (AGN). A major objective is to study the statistical properties of current methods of time-lags estimation in the presence of data gaps as well for light curves with limited duration, by generating synthetic light curves and time-lags spectra. Bayesian inference and/or classical model-fitting statistical methods will be applied to fit physical models to the observed spectra, and infer information about the geometry and the physical processes in the innermost region of AGN. For more details and application deadlines please visit the EURAXESS post.

University of Naples Federico II, Italy

Project 4, Constraining the optical/UV continuum variability of AGNs through large- scale surveys: characterise the multiwavelength variability properties of large (type-I and type-II) AGN samples through long-term monitoring surveys, with both archival (GAIA, ZTF, VST, CRTS etc.) and next generation (EUCLID, LSST) data. The proposed approach will use forward-modelling time-series simulations and novel diffeomorphic transformations to derive unbiased UV/optical time-lags and variability measurements, in order to constrain the dependence of the UV/optical variability on black hole mass, Eddington ratio, line-of-sight obscuration and redshift and use these results to probe the physics of the accretion flows, test the unification model, as well as to select complete AGN samples for demographic studies. For more details and application deadlines please visit the EURAXESS post.

University of Belgrade - Faculty of Mathematics, Serbia

Project 5, Decomposing optical accretion disk through time-series modelling: develop innovative and open-source deep-learning algorithms for characterising time series, which are scalable to handle big data from large astronomical time-domain surveys. Based on the multi-data from current time-domain surveys it will investigate accretion disk of type-I active galactic nuclei (AGNs) in preparation for the transformative Rubin observatory survey - Legacy Survey in Space and time (LSST). Based on unsupervised learning and identification of AGNs sub-classes of peculiar and unknown (never seen before) variability patterns (e.g. extremely variable or periodic signals), the project will explore complex dynamical behaviour of the accretion-disk, such as disk-perturbations or binary black-hole systems prior to coalescence, giving a glimpse into the common processes for accretion disks on all back hole mass scales. For more details and application deadlines please visit the EURAXESS post.

Nicolaus-Copernicus Astronomical Center, Polish Academy of Sciences, Poland

Project 6, Temporal and dynamical behaviour of multi-phase accretion flow: model optical/ultraviolet and X-ray variability observations of AGNs, to constrain the structure and physical conditions of the accretion disk, its connection to winds and BLR. This task will be achieved by developing and testing a phenomenological multi-phase model of accretion flows based on the assumptions of a magnetically supported disk and the equilibrium between magnetic heating and radiative cooling. The PhD candidate will extend a multi-phase accretion model by implementing temporal properties and predictions on multiwavelength variability and dynamical behaviour by implementing momentum equation. The comparison to the data will be a final step and PhD conclusion on the importance of multi-phase accretion in AGN evolution. For more details and application deadlines please visit the EURAXESS post.

Netherlands Institute for Space Research

Project 7, The Outflows and feedback from supermassive black holes using machine learning techniques: Supermassive black holes accretion and ejection mechanisms are the subject of intense study, due to their importance in the compact object origin and sustenance as well as their role in the growth and evolution of galaxies in the Universe. Recently, timing-spectroscopy methods, applied to high quality X-ray data has been developed to study the properties of AGN outflows (e.g. Silva, Uttley & Costantini 2016, Juranova, Costantini & Uttley 2022), showing their potential in determining crucial physical parameters, like distance and density, of the winds, with far-reaching consequences in our understanding of active galactic nuclei feedback. This project aims at the study of supermassive black holes ejection mechanisms using timing and spectroscopy techniques applied to X-ray data. Particular emphasis is given to developing and testing machine learning techniques to make use of the increasingly complex models and data sets from present (XMM-Newton, Chandra, XRISM) and future (e.g. NewAthena) X-ray missions.

University Roma “Tor Vergata”, Italy

Project 8, The Investigating Accretion Disk Winds and their Impact on Black Hole Growth and Galaxy Ecosystem: employ machine learning techniques to model photo-ionised accretion disk winds in AGN, with a focus on ultra-fast outflows. By generating synthetic high-resolution spectra and analysing large X-ray datasets (e.g., XMM-Newton, XRISM), the project aims to characterise the physical properties of these winds, such as their mass flux and energetics. Bayesian inference methods will be applied to compare X-ray observations with multi-wavelength data (e.g., ALMA, JWST), offering new insights into AGN feedback mechanisms and the influence of AGN winds on black hole growth and the broader galaxy ecosystem. For more details and application deadlines please visit the EURAXESS post.

Max Planck Institute of Extraterrestrial Physics, Germany

Project 9, Identification and characterisation of Einstein Probe-discovered Tidal Disruption Events and Quasi-Periodic Eruptions: 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. For more details and application deadlines please visit the MPE IMPRS website.

University of Nova Gorica, Slovenia

Project 10: Identification and characterisation of Tidal Disruption Events discovered by Vera Rubin Observatory: use Tidal Disruption Events (TDEs) detected in optical by Vera Rubin Observatory’s LSST (expected to start in 2025) to study their multi-wavelength properties (using also data from other instruments, e.g. Einstein Probe) and significantly increase the sample of known TDEs. Rubin’s LSST will detect and alert on the order of millions of transient events every night, among which there will be about 10 TDEs. The aim of this project is to develop and use innovative machine-learning-based algorithms to identify TDEs, and compile systematically selected samples of high-confidence optical TDEs. Together with theoretical models of TDEs long-term evolution, this data will be used to constrain the properties of the supermassive black holes and disrupted stars, address the physical nature and location of optical and X-ray emission and the connection between TDEs and Quasi-Periodic Eruptions (QPEs). Possible side-product of the project could be identification of extreme outliers leading to potential discoveries of new types of transients. For more details and application deadlines please visit the EURAXESS post.

University of Bristol, UK

Project 11, X-ray reverberation modelling of black hole accretion discs: develop new models to describe the X-ray spectra and time variability of accretion discs around supermassive black holes. These models will allow extended corona shapes and velocities, realistic disc geometries, and different spacetimes to be investigated. The energy dependent time lags between the continuum emission from the corona and the reprocessed “reflection” spectrum from the disc will be calculated. The goal is to provide an open-source suite of models that the community can use to fit X-ray time lags, and to constrain the corona and disc geometries. For more details and application deadlines please visit the EURAXESS post.