open positions

We are looking for a student assistant, starting after 1.10.23!

Your Tasks:
– You will help with administrative tasks like writing reminders and preparing coffee receptions and being our scientific coordinators “right hand” in busy times.
– You will support the public outreach activities of the SFB 1601.

Your Profile:
– You are fluent in German and English
– You study physics or physics didactics
– It is important that you like working with children and teenagers, mainly with females. You would carry out public outreach projects with them and would have to explain e.g. programming to them. You should feel comfortable to give short talks.

Your Benefit:
– We are happy if you creatively develop your own outreach projects.
– Working hours can be negotiated. Your working times are flexible.

[August 25] The deadline to apply for PhD-positions is over! We got many interesting applications and we are busy with the selection process. Further applications or questions cannot be considered.

The new Collaborative Research Center 1601 is a joint venture of the I. Physics Institute (University of Cologne), the Regional Computing Centre Cologne, the Argelander Institute for Astronomy (University of Bonn), the Max Planck Institute for Radio Astronomy (Bonn) and the Forschungszentrum Jülich.

Our research on the “Habitats of Massive Stars across Cosmic Time” combines four methodological pillars: observational astronomy, instrumentation, laboratory astrophysics, and computational astrophysics. With the start of CRC 1601 on October 1st 2023, we offer

24 PhD positions in Astrophysics (m/f/d) 

in the different methodological pillars to highly motivated and talented students. We provide a cutting-edge research environment, a unique international research collaboration, and state-of-the-art technologies. The list of PhD projects can be found below.

The PhD position start dates can vary and will be individually agreed upon, with the possibility of beginning from October 1st, 2023. The contract is on a  fixed term basis for 2 + 1 years.

PhD students within CRC 1601 will profit from an international, (inter-)active student body and the large research network established between the participating institutions and beyond. The structured PhD training programme is associated with the Bonn-Cologne Research School for Physics and Astronomy (http://www.gradschool.physics.uni-bonn.de).

Payment is based on work contracts (including health and social benefits) according to 66% of the German TVL-E13 scale if the necessary qualifications are met (see below).

Your profile:

  • You have a degree (MSc. or equivalent) in physics / astrophysics / astronomy / computer science or comparable.
  • You are highly motivated to work in an vibrant, multicultural collaboration.
  • You are fluent in English (written and spoken).
  • You can think analytically and work independently, systematically and constructively.
  • Experience in writing research papers or scientific grant proposals is a plus.

Applications must be submitted as a single pdf-file containing a cover letter, CV, publication list, a statement on research interests (max. 2 pages). The cover letter of your application must include the reference numbers of up to 3 PhD projects from this website.

Please also name 2 contact persons (including their email) who have committed to write a letter of recommendation. By sending your application you give your consent to forward your documents to the project leaders of the CRC 1601.

Please submit your application until 15.8.2023 to: sfb1601-application@ph1.uni-koeln.de

We are committed to equal opportunities and diversity. Women are especially encouraged to apply. We strongly support balancing work and family life. We also welcome applications from people with special needs.

(ref. #1) 1 PhD-position available in
Project A1 “Physics and chemistry in star-forming regions with low metallicity”

Peter Schilke
I. Physics Institute, Cologne

We want to investigate how much environmental conditions modify the properties of star formation, such as timescales, clump mass function, mass flow and feedback, and to also use the chemical composition as a tracer. The project will focus on studying the star formation properties of high-mass star-forming regions in the LMC/SMC using radio and sub-mm interferometric telescope data from ALMA and ATCA (and in the future MeerKAT/SKA), as well as larger scale studies with single-dish telescopes including CCAT-p, APEX and archival data to get a coherent picture. To investigate the influence of the environment on the star formation process and also the impact of feedback processes, we will also add a multi-wavelength analysis using additional IR and X-ray data.  The observational results will be compared to simulations conducted elsewhere in CRC 1601. 

Required skills:
Within the thesis, data has to be analyzed, which requires becoming familiar with data reduction packages and scripts, most of which are written in python.  The work will take place in an international group, so good communication skills in English are required.  Likewise proposals have to be written, and results communicated in articles.  

Further information:
https://astro.uni-koeln.de/schilke

ALMA 1.2 mm continuum maps of star-forming regions in the LMC. A variety of morphologies are present, at first glance reminiscent of Galactic star-forming regions. A deeper analysis will show if the fragmentation properties, core mass functions etc. are also similar, and if the dynamics, as traced by molecular line maps (not shown here), are also comparable.

(ref. #2) 1 PhD-position available in
Project A1 “Physics and chemistry in star-forming regions with low metallicity”

Arnaud Belloche
Max Planck Institute for Radio Astronomy, Bonn

The project aims at investigating the impact of metallicity and dust-to-gas ratio on the chemistry of high-mass star forming regions in the outer parts of the Galaxy where these quantities are lower than in the inner Galaxy. The candidate will analyze interferometric (ALMA/NOEMA) imaging spectral line surveys and determine the chemical composition of hot cores that we previously identified with single-dish telescopes. The observational results will be compared to predictions of state-of-the-art chemical models of hot cores, in close collaboration with an external expert, as well as to the chemical composition of hot cores in the inner Galaxy and in the Magellanic clouds.

Required skills:
The candidate will analyze interferometric spectral line data. This will require becoming familiar with data reduction packages (CASA, GILDAS) and writing scripts (python). Good communication skills in English both in speaking and writing are required. The candidate will write observational proposals and communicate the results of the thesis in scientific articles.

Further information:
https://www.mpifr-bonn.mpg.de/forschung/submm

Ratio of molecular abundances relative to methanol between a hot core with reduced metallicity and dust-to-gas ratio and a hot core with solar metallicity as predicted by a state-of-the-art chemical model. The candidate will use interferometric data to investigate if such model predictions match the chemical composition of hot cores in the outer Galaxy.

(ref. #3) 1 PhD-position available in
Project A2 “Characterisation of Galactic high-feedback habitats”

Peter Schilke
I. Physics Institute, Cologne

In this project, we aim to conduct a comprehensive, detailed investigation of the physical and chemical structure of high-feedback, star-forming habitats distributed throughout the Galaxy in the range of different environments. We will do so by combining analysis of both archival and newly acquired high-resolution, multi-frequency observations with the analysis of post-processed synthetic images from existing and new MHD-models. This PhD candidate will be focused on the study of the spatial and density structure of the forming clusters, and the study of the macroscopic motions and mechanical feedback as sources of turbulence. This will entail determining the velocity field and mass flows across spatial scales and disentangling them from feedback effects. The observational results will be compared to simulations conducted elsewhere in CRC 1601.  

Required skills:
Within the thesis, data has to be analyzed, which requires becoming familiar with data reduction packages and scripts, most of which are written in python.  The work will take place in an international group, so good communication skills in English are required.  Likewise proposals have to be written, and results communicated in articles.  

Further information:
https://astro.uni-koeln.de/schilke

Fitting of vibrationally excited lines (here from HC3N in an ALMA line survey towards SgrB2 (M)). The upper row shows a 1.3 mm continuum map of the region (Sánchez-Monge et al. 2017), with the two sources fitted shown with ellipses. In source A1 (the lower spectra in the bottom row) fitting of the vibrationally excited HC3N lines yielded a temperature of 550 K, while in source A10 (upper spectra) a temperature of 145 K was determined

(ref. #4) 1 PhD-position available in
Project A2 “Characterisation of Galactic high-feedback habitats”

Peter Schilke
I. Physics Institute, Cologne

In this project, we aim to conduct a comprehensive, detailed investigation of the physical and chemical structure of high-feedback, star-forming habitats distributed throughout the Galaxy in the range of different environments. We will do so by combining analysis of both archival and newly acquired high-resolution, multi-frequency observations with the analysis of post-processed synthetic images from existing and new MHD-models. 
The topic of the PhD will be the characterisation of the chemical history and cluster evolution, includes producing synthetic maps of various molecular transitions based on chemical post-processing of MHD models,  and comparing, in a statistical way, with observational results.

Required skills:
Within the thesis, data has to be analyzed, which requires becoming familiar with data reduction packages and scripts, most of which are written in python.  The work will take place in an international group, so good communication skills in English are required.  Likewise proposals have to be written, and results communicated in articles.  

Further information:
https://astro.uni-koeln.de/schilke

Radially averaged abundance variation of CH3OH as a function of time, in a star formation model including episodic accretion bursts. 

(ref. #5) 1 PhD-position available in
Project A3 “A high-resolution view of massive stars in peculiar habitats”

Lucas Labadie, Florian Peißker
I. Physics Institute, Cologne

We want to conduct the small (100 AU) and large-scale (1000 AU) interplay between massive stars in their respective environment. It is planned to carry out a multi-wavelength analysis of different habitats to constrain universal and specific star formation processes. Different tracers are used to identify high-mass Young Stellar Objects to explore the interaction with the interstellar medium. Habitats, such as the Galactic Center, the Large Magellanic Cloud, or Galactic massive star clusters, are targeted to investigate the companion and multiplicity fraction. It is planned to use state of the observation facilities, such as the Very Large Telescope, ALMA, and JWST.

Required skills:
We expect basic knowledge in data reduction (e.g., for ALMA and VLT data) and programming skills (e.g., Python). Knowledge of radiative transfer models is preferable but optional.

Special requirements:
Regular trips to conferences or observation sites 

Further information:
https://astro.uni-koeln.de/labadie

Selection of different habitats that are part of the project. The large overview map shows the Galactic center, whereas the small inlet represents young embedded clusters with ongoing star formation processes. All images were observed with NACO, which was mounted at the VLT/Chile.

(ref. #6) 1 PhD-position available in
Project A5 “Massive star formation and cluster evolution”

Prof. Dr. Stefanie Walch
I. Physics Institute, Cologne

We will investigate the formation and evolution of massive stars and their associated star clusters on small scales (≲1 – few pc) by means of combining state-of-the-art magneto-hydrodynamic (MHD) and N-body simulations. This PhD position will mostly study the formation of the star cluster, following the collapse of dense, prestellar cores through the massive star and star cluster formation process and until the development of ultra-compact HII regions. The initial conditions are informed by state-of-the-art observations of massive star forming regions. The results of these simulations will be further used to inform long-term star cluster evolution studies. Project A5 is a collaboration with our partner institution Forschungszentrum Jülich.

Required skills:
Excellent programming skills, analytical skills, and an astrophysics education are required. A strong motivation to work on high-performance compute problems is necessary. Knowledge of different programming languages like Fortran, C++, python, or other, and/or parallelization techniques (MPI) is a plus.  

Further information:
https://astro.uni-koeln.de/walch-gassner

Volume-rendering of a massive star formation simulation (red: ionized gas; blue: atomic gas; green: molecular gas). The feedback from the new-born massive star ionizes and disperses the parental core. Image credit: A. Klepitko

(ref. #7) 1 PhD-position available in
Project A5 “Massive star formation and cluster evolution”

Susanne Pfalzner
Forschungszentrum Jülich

Within this PhD project we aim to fill the gap between the star cluster formation models and the simulations of the evolution of the fully formed star clusters. We will apply different numerical approaches:nFirst, since the star formation history and the phase-space characteristics of the stars are essential for consecutive cluster evolution, we start simulating the evolution of the star cluster, starting out with simple MHD molecular cloud collapse simulations. The project will use the results of the cluster formation simulations as a starting point. We will compare the N-body results with the observed cluster properties. Depending on the match or mismatch, we use that as a feedback loop to assess how realistic the molecular collapse simulations are. We will adapt the assumptions in the cloud collapse simulations to successively reach more and more realistic realisations.

Required skills:
First experience in using high-performance simulation codes. experience in Fortran would be an advantage, but is not strictly necessary. Similarly, background knowledge of star cluster formation or cluster evolution would be welcome.

Special offer: Access to HPC computing facilities at FZJ.

Further information:
https://www.fz-juelich.de/en/ias/jsc/about-us/structure/simulation-and-data-labs/sdl-astrophysics-and-astronomy

Example snapshot of an N-body simulation of the dynamics of a star cluster. The symbol sizes represent the mass of the star and the colours the strengths of the interaction experienced by the environment.

(ref. #8) 1 PhD-position available in
Project A6 “Tracing star formation through observations of UV chemistry”

Volker Ossenkopf-Okada, Markus Röllig
I. Physics Institute, Cologne

The project plans to improve our understanding of the physics of photon-dominated regions (PDRs) where the UV radiation from young massive stars creates a characteristic chemistry and excitation in the ISM. The applicant is expected to work on the continued development of the KOSMA-tau PDR model code with an emphasis on  fitting new observations of PAHs and H2 from the JWST. Additional changes on the code side are driven by the need to model typical PDRs in high-redshift galaxies with low metallicities, a higher cosmic microwave background, and a high cosmic ray and X-ray flux. The model development is a joint effort between Markus Röllig at the Physikalische Verein Frankfurt, and the University of Cologne so that the PhD student will work with guidance from both sides involving regular travels to Frankfurt. 
The applicant is expected to also contribute to the academic environment at the institute.

Required skills:
– University degree (diploma or MSc.) in physics, astronomy or a related field
– Background in astrophysics
– Scientific programming experience, knowledge of FORTRAN
– Strong interest in data analysis and numerical simulations
– Good English communication skills

Specials requirements:
Ability for regular trips between Cologne and Frankfurt

Special offer:
Possibility to perform practical observations at the ground-based telescopes in Chile and Spain

Further information:
Röllig, M., Ossenkopf-Okada, V.; “The KOSMA-τ PDR model. I. Recent updates to the numerical model of photo-dissociated regions”, A&A 2022, 664, id.A67

Schematic picture of the KOSMA-tau PDR modelling approach: External UV radiation heats a cloud and induces a chemical layering structure from photo-dissociation. In particular the excitation of H2 is still not well understood.

(ref. #9) 1 PhD-position available in
Project A6 “Tracing star formation through observations of UV chemistry”

Volker Ossenkopf-Okada
I. Physics Institute, Cologne

The project plans to improve our understanding of the ISM in regions where the UV radiation from young massive stars creates a characteristic chemistry and excitation in terms of photon-dominated regions (PDRs). The applicant is expected to work on a flexible numerical framework to construct any 3D geometry of a particular region from volume units (voxels) that are described by the KOSMA-tau-3D model setup. The framework should be used to compute the emissions from individual star-forming regions and for a chemical post-processing of configurations from the larger MHD simulations in project B6 so that the KOSMA-tau-3D voxels provide a subgrid model to the MHD simulations for a more detailed PDR physics treatment. The applicant therefore works at the interface between different simulation projects, having to communicate with each of them. The applicant is expected to also contribute to the academic environment at the institute.

Required skills:
– University degree (diploma or MSc.) in physics, astronomy or a related field
– Background in astrophysics
– Scientific programming experience, preferably in Python
– Strong interest in data analysis and numerical simulations
– Good English communication skills

Further information:
Yanitski, C., Ossenkopf-Okada, V., Röllig, M., “Constraining the Galactic far-UV field using a clumpy PDR model”,  Physics and Chemistry of Star Formation: The Dynamical ISM Across Time and Spatial Scales. Edited by V. Ossenkopf-Okada et al. ISBN: 978-3-00-074740-3. Published by Universitäts- und Stadtbibliothek, Köln, 2023, p.265

Illustration of the KOSMA-tau-3D model setup where volume cells are populated by ensembles of PDR clumps. Their superposition explains the observed emission.

(ref. #10) 1 PhD-position available in
Project B1: “Conditions in dense clumps as a cluster forming reservoir in different environments – astrochemical simulations”

Daniel Seifried
I. Physics Institute, Cologne

Star formation is a hierarchical multiscale process, which the successful candidate will study by means of 3D, astrochemical simulations. In particular, the dynamics of molecular cloud properties on scales of a fraction of a parsec to several parsecs are of interest in this project, thus bridging the gap between individual cores and the larger cloud scales. Moreover, the applicant will analyse the physical properties and the detailed chemical composition in molecular clouds forming in different environments reaching from solar neighbourhood conditions to extreme conditions like in the Central Molecular Zone.

Specifically, the project includes the analysis of state-of-the-art 3D, MHD simulations of molecular clouds in different environments to assess e.g. how mass is accreted onto filamentary substructures. At the heart of the project lies the modelling of the chemical evolution of these simulations with a novel post-processing routine (Panessa et al., 2023, see link below). The successful candidate will analyse dense gas tracers like HCN, N2H+ etc. used in current observations. Moreover, in tight collaboration with colleagues within the CRC 1601, we offer to compare the outcomes to real observations.

Required skills:
The successful candidate should have very good programming skills, ideally in more than one programming language. Knowledge in either handling big data, experience with MHD simulations or astrochemistry is desired. Interest in comparing simulation data with observational data would be beneficial.

Further information:
https://astro.uni-koeln.de/walch-gassner/research-group
https://hera.ph1.uni-koeln.de/~seifried/

Synthetic HCO+ column density maps of a simulated molecular cloud presented in Panessa et al., 2023

(ref. #11 & 12) 2 PhD-positions available in
Project B2: “Studying stellar feedback in the Milky Way and Magellanic Clouds”

Dominik Riechers, Robert Simon, Frank Bigiel
I. Physics Institute, Cologne

This project aims at characterising the feedback of massive stars and their embedding habitats in the Milky Way and Magellanic Clouds. Starting in 2025, we will conduct novel large-scale spectroscopic surveys with the Fred Young Submillimetre Telescope (FYST) at the CCAT observatory in Chile in mid-J CO rotational lines and fine structure transitions of atomic carbon. These lines trace the warm, dense gas associated with stellar feedback and the atomic phase of Photon Dominated Regions (PDRs) and CO-dark H2. 

The PhD candidates will take part in the observations and data reduction and contribute to the analysis and interpretation of the data. This includes the combination with available complementary surveys, the characterisation of the physical and statistical properties of massive stellar habitats in the Milky Way (PhD1) and the Magellanic Clouds (PhD2 in close collaboration with F. Bigiel in project B3), and modelling and simulations (e.g., PDRs) in collaboration with other CRC projects.

Required skills:
For both theses, the handling of large data sets and their analysis/interpretation requires the application of existing and development of new analysis tools, mostly written in python. Good programming skills are required and an astrophysical background would be ideal. Good communication skills in English are required.  

Further information:
https://astro.uni-koeln.de/riechers/research-group
CCAT Observatory: http://www.ccatobservatory.org
CHAI instrument: https://astro.uni-koeln.de/graf/chai

Top left: Rendering of the Fred Young Submillimetre Telescope (FYST) near the summit of Cerro Chajnantor in Chile. Top right: The Large Magellanic Cloud at infrared wavelengths (Herschel: 250 μm (red), 100 & 160 μm (green); Spitzer 24 & 70 μm (blue)). Bottom: Prominent high mass star forming regions of the southern Milky Way in (sub)mm and mid-IR continuum emission (APEX/ATLASGAL & Planck: red; Spitzer/GLIMPSE: blue).

(ref. #13) 2 PhD-positions available in
Project B3: “Molecular gas spectroscopy across nearby galaxies“

Prof. Frank Bigiel
Argelander Institute for Astronomy, Univ. Bonn

As in project B2 above, this project will focus on new comprehensive spectroscopic surveys with the FYST telescope at the CCAT observatory in Chile of mid-J CO rotational lines and fine structure transitions of atomic carbon, but here focusing on nearby galaxies. These new data sets will allow to study the physical conditions of molecular gas across local galaxies and linking these to local properties of the interstellar medium and the star formation activity in these galaxies.
This is possible due to a comprehensive, existing set of ancillary multi-wavelength data to characterize stars and their feedback, the ISM, dust and metallicities and in particular molecular gas physics across these galactic disks.

Required skills:
Good python coding skills will help to get started quickly with data reduction, analysis and interpretation and some background in interstellar medium, star formation and/or radio astronomy would be an asset.

Further information:
https://astro.uni-bonn.de/de/forschung/radioastronomy-ism
CCAT Observatory: http://www.ccatobservatory.org
CHAI instrument: https://astro.uni-koeln.de/graf/chai

  • den Brok, Bigiel, Sliwa, Saito, Usero, Schinnerer, Leroy, Jiménez-Donaire, et al., “A CO isotopologue Line Atlas within the Whirlpool galaxy Survey (CLAWS)”, A&A 662, A89 (2022). 
  • Bigiel, de Looze, Krabbe, Cormier, Barnes, Fischer, Bolatto, Bryant, et al., “SOFIA/FIFI-LS Full-disk [C II] Mapping and CO-dark Molecular Gas across the Nearby Spiral Galaxy NGC 6946”, ApJ 903, 30 (2020). 

Example of multi-molecular spectral line data set of the nearby spiral galaxy M51 (den Brok, Bigiel et al. 2022). Such comprehensive data sets allow a detailed assessment of local gas physics and the impact of stellar feedback across galaxies.

(ref. #14) 1 PhD-position available in
Project B4: “Magnetic fields on galactic scale – simulations“

Daniel Seifried
I. Physics Institute, Cologne

In this project the successful candidate will investigate the role magnetic fields play during the process of massive star formation, by means of synthetic observations obtained from 3D, MHD simulations of the ISM and embedded molecular clouds. The project will contain radiative transfer calculations to model the origin and propagation of polarised synchrotron radiation in the ISM as well as the effect of Zeeman splitting (e.g. Seifried et al., 2020 and Reissl et al., 2021, see links below).

The candidate will investigate how environmental conditions in the ISM like it’s metallicity affect these processes and will analyse how well the magnetic field in the ISM can be measured e.g. by means of Faraday rotation measures. Furthermore, the candidate will closely collaborate with colleagues within the CRC 1601 to compare the results with real observations, to obtain a better understanding of the interplay and the relative importance of turbulence, gravity, magnetic fields and the chemical state of the ISM.

Required skills:
The successful candidate should have very good programming skills, ideally in more than one programming language. Knowledge in either handling big data, experience with MHD simulations or radiative transfer calculations is desired. Interest in comparing simulation data with observational data would be beneficial.

Further information:
https://astro.uni-koeln.de/walch-gassner/research-group
https://hera.ph1.uni-koeln.de/~seifried/

Column density of a simulated molecular cloud and the magnetic field direction (black bars) inferred from synthetic dust polarisation maps (Seifried et al., 2020).

(ref. #15) 1 PhD-position available in
Project B5: “Supernova and neutron star driven feedback under the microscope“

Prof. Dr. Stefanie Walch
I. Physics Institute, Cologne

Massive stars leave their mark in various important ways. Their life and death are major contributors to the chemical enrichment of the universe as a whole, and their explosive ends provide cosmic rays and sources of energy for the ISM. Supernovae leave behind compact objects, especially neutron stars, which literally are beacons of past massive star formation, and which themselves can be used to probe the ISM, its ionised component, and its turbulence spectrum. We aim to study the interaction of supernovae, their remnants and the ISM by linking observations with simulations, comparing the details of supernova feedback calculations with detailed observational investigations of supernova remnants that interact with nearby dense gas. This particular PhD position is focussed on the simulation part of the collaborative study with our partner institution MPI for Radioastronomy.

Required skills:
Excellent programming skills, analytical skills, and an astrophysics education are required. A strong motivation to work on high-performance compute problems is necessary. Knowledge of different programming languages like Fortran, C++, python, or other, and/or parallelization techniques (MPI) is a plus. 

Further information:
https://astro.uni-koeln.de/walch-gassner

Volume-rendering of the cooling radiation from a simulated young supernova remnant showing the optical and FUV (E < 13.6 eV, red), EUV (13.6 eV < E < 100 eV, blue) and X-ray emission (100 eV < E, green) of the cooling remnant. Each side of the cube is approximately 75 pc. Credit: E. Makarenko.

(ref. #16) 1 PhD-position available in
Project B5: “Supernova and neutron star driven feedback under the microscope“

Michael Kramer
Max Planck Institute for Radio Astronomy, Bonn

The student will identify and study sites of Supernova-Interstellar medium interaction with suitably related  pulsars and magnetars, using archival and new data. The student will undertake and analyse radio pulsar observations for scintillometry studies. Using a combination with  dedicated spectral line and imaging observations, pulsar polarisation studies and a comparison with theoretical models, in collaboration with the other participants in B5 and the CRC, the student will asses the impact of neutron stars, their birth properties and their formation process on the surroundings in gas-rich environments.

Required skills:
Sound understanding of (astro-)physics and radio astronomy, ability to code, experience in independent research

 

Further information:
https://www.mpifr-bonn.mpg.de/forschung/fundamental

The S147 remnant of
a supernova that created PSR J0528+2817, which is moving away from the SNR centre. A
combination of X-ray and radio observations clearly demonstrates an alignment of the pulsar’s spin and velocity vector (Yao et al. 2021), as an imprint of processes most likely involving supernova fallback (Janka et al. 2022). Scintillometry obser-
vations identify the remnant edge as a scattering screen. Figure by Yao et al. 2021.

(ref. #17) 1 PhD-position available in
Project B6: “Stellar habitats in different environments”

Prof. Dr. Stefanie Walch
I. Physics Institute, Cologne

In this project, we will investigate the formation and evolution of massive star habitats for different environmental conditions typically found throughout cosmic time by means of 3D magneto-hydrodynamic (MHD) simulations with our extended multi-physics simulation framework which is based on the modular, adaptive mesh refinement code FLASH.
We will address the importance of external (galactic environment, e.g., surface densities of gas and old stars, spiral arm potential or merger, high radiation environment near a galactic centre, etc.) vs. internal properties (turbulence, substructure, magnetic field strength) for evaluating which conditions promote or hinder massive star formation. Apart from carrying out the simulations and the analysis, a very important aspect of this project is to contribute further improvements to the simulation code, e.g., concerning the radiative transfer implementation.

Required skills:
Excellent programming skills, analytical skills, and an astrophysics education are required. A strong motivation to work on high-performance compute problems is necessary. Knowledge of different programming languages like Fortran, C++, python, or other, and/or parallelization techniques (MPI) is a plus. 

Further information:
https://astro.uni-koeln.de/walch-gassner

Dwarf galaxy simulations. We show the side view (top row) and the face-on view (bottom row) of the inner part of the galaxy. A run with ionising radiation from massive stars and supernova feedback (left column) is compared to a run with only supernova feedback (right column). Only SN feedback leads to more massive clusters, which drive larger bubbles that disrupt the disc. With ionising radiation on the other hand, star formation is locally terminated before very massive star clusters have formed, leading to a more gentle and less bursty time evolution. Credit: P. Nürnberger

(ref. #18) 1 PhD-position available in
Project B7: “Superconductor Insulator Superconductor (SIS) mixer development“

Dominik Riechers, Netty Honingh, Urs Graf
I. Physics Institute, Cologne

We are presently finalizing a 64-pixel SIS focal plane heterodyne array at 450-500 GHz which is the lower frequency band of the CHAI instrument. You will develop ( design and test) a side band separating SIS mixer for these same frequencies. Fabrication of the devices will be done in-house by the cleanroom staff. After studying the existing balanced SIS mixers and their specifications adapted to use in a heterodyne array, you will embark on the design of side band separating SIS mixers, also suitable for focal plane arrays. For the intermediate frequency part of the mixer (4-8 GHz, probably) we plan to make use of modern digital electronics to support the side band separating process to achieve optimum performance. This will be done within the SFB1601 in cooperation with subproject C8.

Required skills:
To apply you need a solid background in physics apparent by a BSc and a MSc degree. The latter preferably on a relevant subject for the advertised work. Knowledge and experience with microwave design and/or measurements will be an advantage. Some affinity with digital signal processing would be desirable. Interest in micro fabrication is welcome. Proficiency in English in speech and in writing. You should be able to work and communicate productively with many different people from professors to engineers and workshop, partly also in the German language.

Further information:
https://astro.uni-koeln.de/astrophysical-instrumentation
CCAT observatory: http://www.ccatobservatory.org/
relevant SFB 956 page: https://www.sfb956.de/project/d

Superconductor-Isolator-Superconductor tunnel junction suitable for frequency mixing up to 1.5 THz

(ref. #19) 1 PhD-position available in
Project B7: “Superconductor Insulator Superconductor (SIS) mixer development“

Dominik Riechers, Netty Honingh, Urs Graf
I. Physics Institute, Cologne

You will develop SIS mixers up to 1.4 THz to allow the observing astronomers to make use of the highest atmospheric windows that can be reached by the CCAT observatory. You start by familiarizing yourself with designs and results at the higher frequency band (790-820 GHz) of the CHAI instrument (website) and gather hands-on experience by taking part in the testing of  CHAI, to become acquainted with the test methodology. Hopefully well prepared you will then work on designs of ultra-high frequency SIS mixers. Material choices for the SIS junctions as well as for the surrounding circuitry are an important part of the design process and might require pre-tests.  Fabrication will mostly be done by the cleanroom staff, but evaluation of the designs (test set-up) is your task. Initially these mixers are meant to be single pixel mixers, or part of a small ( 4 pixel) focal plane array. Probably starting with a standard double side band design, designs for balanced and/or side band separating configurations are envisaged. 

Required skills:
To apply you need a solid background in physics apparent by a BSc and a MSc degree. The latter preferably on a relevant subject for the advertised work. A thorough basic knowledge of solid-state physics and superconductivity is very desirable. Interest in micro fabrication is welcome. Proficiency in English in speech and in writing. As a member of the CHAI instrument team you should be able to work and communicate productively with many different people from professors to engineers and workshop, partly also in German. Practical skills, e.g. in electronics, mechanics, computers will be much valued.

Further information:
https://astro.uni-koeln.de/astrophysical-instrumentation
CCAT observatory: http://www.ccatobservatory.org/
relevant SFB 956 page: https://www.sfb956.de/project/d

First attempt to a side band separating balanced SIS mixer at 460 GHz, fabricated at PH1, at the university of Cologne.

(ref. #20 & 21) 2 PhD-positions available in
Project C2 “The dust-obscured cosmic star formation history beyond the Herschel confusion limit”

Dominik Riechers, Frank Bertoldi
(ref. #20) PhD1: I. Physics Institute, Cologne
(ref. #21) PhD2: Argelander Institute for Radio Astronomy, Bonn

The successful candidates will work on the preparation and execution of (sub-)millimeter continuum surveys with the new FYST/CCAT telescope, which will have first light in late 2024.
One candidate will work on the combination and cross-matching of CCAT and Herschel
data (as well as any ancillary information available) for infrared spectral energy distribution analysis of star-forming galaxies in the early universe. The goal of this project is to develop a model of the underlying dusty galaxy population across cosmic history.
The other candidate will work on the cross-matched data to identify the strongest candidates for the most distant dusty starbursts at z>5, and follow-up observations to confirm their distance. Preparatory efforts and follow-up studies for both projects may include observations with other facilities like the APEX telescope, ALMA and the VLA.


The Bonn doctoral student will participate in the preparation, observation, and analysis of the deep extragalactic galaxy survey with FYST. The science goal is to trace the star formation history of the universe to unprecedented depth and large spatial scales. For this we will develop novel statistical and ML methods to identify and characterize individual galaxies and constrain population properties.

Required skills:
Experience with programming, e.g., in the python language, telescope data analysis, interferometry, gravitational lens modeling, MCMC-based statistical analysis and/or scientific writing will be regarded as a plus for this position.
The analysis of large data sets requires the application and development of analysis tools that are mostly written in python. Programming skills and a background in astrophysics and statistics are recommended.

Further information:
https://astro.uni-koeln.de/riechers/research-group
CCAT Observatory: http://www.ccatobservatory.org

Scrutinising several hundred thousand galaxies observed at infrared and submillimetre wavelengths by ESA’s Herschel space observatory, astronomers have identified a very rare instance of a massive object in the very early Universe. Further observations obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) at higher resolution (right inset) revealed that the source consists not just of one ancient, massive galaxy, but of a pair of distinct massive galaxies about to merge.

(ref. #22) 1 PhD-position available in
Project C3 “Tomography of cosmic reionization and large-scale structure of the Universe at redshifts 3-8”

Frank Bertoldi
Argelander Institute for Radio Astronomy, Bonn

The Bonn doctoral student will participate in the preparation, observation, and analysis of the spectroscopic epoch of reionization galaxy survey with FYST. The science goal is to trace the ionized carbon fine structure line emission and thereby the star formation history at the earliest galaxy formation epoch of the universe. For this we will refine models of the star formation history, of [CII] and CO line emission, and develop tools to separate emission components in the spectral data cube. 

Required skills:
The analysis of large data sets requires the application and development of analysis tools that are mostly written in python. Programming skills and a background in astrophysics are required.

(ref. #23 & 24) 2 PhD-positions available in
Project C7: “The development of a broadband spectroscopy camera (around 0.3 THz) for the CCAT-observatory”

Dominik Riechers, Netty Honingh, Urs Graf, Matthias Justen
I. Physics Institute, Cologne

In this project we are aiming to develop a filterbank with a bandwidth of about 200 GHz and a maximum resolution of 1000, using integrated microwave kinetic inductance detectors (MKIDs) as sensitive readout elements. To make a camera we plan to populate the focal plane of the telescope with many of these filterbanks, which requires a compact design and readout.

We are looking for 2 PhD students who each have their independent task, but who need to cooperate well to make a workable single pixel prototype and perform meaningful tests.

One of 2 PhD students (23) will focus on the development of the MKID optimizing its sensitivity and its noise behavior, keeping in mind space limitations, connection to the filterbank and read-out connection. The design and the fabrication technology can significantly influence of the sensitivity of the MKID and a hands-on optimization will be part of the work. This will require that you do micro-fabrication of (pre-)prototypes under the supervision of the cleanroom staff. The existing measurement set-up will mainly be adapted by the other PhD student (24) on this project. Performing the measurements, and evaluating and understanding the physics and the performance of the detector (PhD student 1) and the RF design (PhD student2) is a task for both students.

Required skills:
To apply you must have a solid knowledge of general physics, visible in a BSc and MSc thesis, the latter preferably on relevant subject for these PhD positions. Please include a copy of the (draft of) your Master thesis in your application documents. To come to a working prototype in the course of 3-4 years you must already have knowledge of (microscopic) superconductivity. Experience in cryogenic measurements or micro-fabrication is a significant advantage. A practical attitude is necessary as are decent communication and cooperation skills. As this is a challenging subject perseverance is will be required.

Further information:
https://astro.uni-koeln.de/astrophysical-instrumentation
CCAT observatory: http://www.ccatobservatory.org/
relevant SFB 956 page: https://www.sfb956.de/project/d

A Microwave Kinetic Inductance  Detector fabricated at PH1, at the university of Cologne.