Welcome.

My name is Sebastian Ohlmann and I am working at the MPCDF (Max Planck Computing and Data Facility) in the Application Support group. I am collaborating with scientists from Max Planck Institutes to improve their HPC codes: developing new features, optimizing, checking algorithms, porting to GPUs and more.

Before, I worked as a Postdoctoral researcher at HITS (Heidelberg Institute for Theoretical Studies) in the group of Prof. Dr. Friedrich Röpke (Physics of Stellar Objects).

Before that, I completed my PhD at Heidelberg University after starting my PhD at the Chair of Astronomy at the University of Würzburg. I did my undergraduate studies at the Karlsruhe Institute of Technology.

My research interests include the hydrodynamic modeling of stellar mergers, Common Envelope phases and Type Ia supernovae.

My Research Interests.

Common Envelopes

In my PhD project, I conducted hydrodynamic simulations of the Common Envelope phase which is an important and still unsolved problem in binary stellar evolution. You can find some explanations in a recent press release of our institute. You can download my PhD thesis from the university library Heidelberg. I also published some articles about hydrodynamic simulations of the Common Envelope phase.

Type Ia supernovae

In my diploma project, I investigated the impact of altering the progenitor white dwarf's composition on Type Ia supernovae. I wrote a thesis and later on published also a paper about this research project.

Find out more about my publications.

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Papers et cetera.

A list of my papers on ADS and arXiv.

Publications by year:

2019 2017 2016 2015 2014

2019

  1. Schneider, F. R. N., Ohlmann, S. T., Podsiadlowski, P., Röpke, F. K., Balbus, S. A., Pakmor, R., & Springel, V. (2019):
    Stellar mergers as the origin of magnetic massive stars,
    Nature, 574, 211, [ADS]
  2. Kirsebom, O. S., Jones, S., Strömberg, D. F., Martínez-Pinedo, G., Langanke, K., Röpke, F. K., Brown, B. A., Eronen, T., Fynbo, H. O. U., Hukkanen, M., Idini, A., Jokinen, A., Kankainen, A., Kostensalo, J., Moore, I., Möller, H., Ohlmann, S. T., Penttilä, H., Riisager, K., Rinta-Antila, S., Srivastava, P. C., Suhonen, J., Trzaska, W. H., & Äystö, J. (2019):
    Discovery of an Exceptionally Strong β-Decay Transition of 20F and Implications for the Fate of Intermediate-Mass Stars,
    Phys. Rev. Lett., 123, 262701
  3. Jones, S., Röpke, F. K., Fryer, C., Ruiter, A. J., Seitenzahl, I. R., Nittler, L. R., Ohlmann, S. T., Reifarth, R., Pignatari, M., & Belczynski, K. (2019):
    Remnants and ejecta of thermonuclear electron-capture supernovae - Constraining oxygen-neon deflagrations in high-density white dwarfs,
    A&A, 622, A74
  4. Goicovic, F. G., Springel, V., Ohlmann, S. T., & Pakmor, R. (2019):
    Hydrodynamical moving-mesh simulations of the tidal disruption of stars by supermassive black holes,
    Monthly Notices of the Royal Astronomical Society, 487, 981, [ADS]

2017

  1. Ohlmann, S. T., Röpke, F. K., Pakmor, R., & Springel, V. (2017):
    Constructing stable 3D hydrodynamical models of giant stars,
    Astronomy and Astrophysics, 599, A5, [ADS]
  2. Wright, W. P., Kneller, J. P., Ohlmann, S. T., Röpke, F. K., Scholberg, K., & Seitenzahl, I. R. (2017):
    Neutrinos from type Ia supernovae: The gravitationally confined detonation scenario,
    Physical Review D, 95, 043006
  3. Kromer, M., Ohlmann, S., & Röpke, F. K. (2017):
    Simulating the observed diversity of Type Ia supernovae . Introducing a model data base,
    Mem. Societa Astronomica Italiana, 88, 312, [ADS]

2016

  1. Ohlmann, S. T., Röpke, F. K., Pakmor, R., & Springel, V. (2016):
    Hydrodynamic moving-mesh simulations of the common envelope phase in binary stellar systems,
    The Astrophysical Journal Letters, 816, L9, [ADS]
  2. Ohlmann, S. T., Röpke, F. K., Pakmor, R., Springel, V., & Müller, E. (2016):
    Magnetic Field Amplification During the Common Envelope Phase,
    Monthly Notices of the Royal Astronomical Society, 462, L121, [ADS]
  3. Seitenzahl, I. R., Kromer, M., Ohlmann, S. T., Ciaraldi-Schoolmann, F., Marquardt, K., Fink, M., Hillebrandt, W., Pakmor, R., Röpke, F. K., Ruiter, A. J., Sim, S. A., & Taubenberger, S. (2016):
    Three-dimensional simulations of gravitationally confined detonations compared to observations of SN 1991T,
    Astronomy and Astrophysics, 592, A57, [ADS]
  4. Pakmor, R., Springel, V., Bauer, A., Mocz, P., Munoz, D. J., Ohlmann, S. T., Schaal, K., & Zhu, C. (2016):
    Improving the convergence properties of the moving-mesh code AREPO,
    Monthly Notices of the Royal Astronomical Society, 455, 1134, [ADS]
  5. Ruiz-Lapuente, P., The, L.-S., Hartmann, D. H., Ajello, M., Canal, R., Röpke, F. K., Ohlmann, S. T., & Hillebrandt, W. (2016):
    The Origin of the Cosmic Gamma-ray Background in the MeV Range,
    The Astrophysical Journal, 820, 142, [ADS]
  6. Jones, S., Röpke, F. K., Pakmor, R., Seitenzahl, I. R., Ohlmann, S. T., & Edelmann, P. V. F. (2016):
    Do electron-capture supernovae make neutron stars?. First multidimensional hydrodynamic simulations of the oxygen deflagration,
    Astronomy and Astrophysics, 593, A72, [ADS]

2015

  1. Marquardt, K. S., Sim, S. A., Ruiter, A. J., Seitenzahl, I. R., Ohlmann, S. T., Kromer, M., Pakmor, R., & Röpke, F. K. (2015):
    Type Ia supernovae from exploding oxygen-neon white dwarfs,
    Astronomy and Astrophysics, 580, A118, [ADS]
  2. Kromer, M., Ohlmann, S. T., Pakmor, R., Ruiter, A. J., Hillebrandt, W., Marquardt, K. S., Röpke, F. K., Seitenzahl, I. R., Sim, S. A., & Taubenberger, S. (2015):
    Deflagrations in hybrid CONe white dwarfs: a route to explain the faint Type Iax supernova 2008ha,
    Monthly Notices of the Royal Astronomical Society, 450, 3045, [ADS]
  3. Seitenzahl, I. R., Herzog, M., Ruiter, A. J., Marquardt, K., Ohlmann, S. T., & Röpke, F. K. (2015):
    Neutrino and gravitational wave signal of a delayed-detonation model of type Ia supernovae,
    Physical Review D, 92, 124013, [ADS]

2014

  1. Ohlmann, S. T., Kromer, M., Fink, M., Pakmor, R., Seitenzahl, I. R., Sim, S. A., & Röpke, F. K. (2014):
    The white dwarf’s carbon fraction as a secondary parameter of Type Ia supernovae,
    Astronomy and Astrophysics, 572, A57, [ADS]

Here, you can get the slides of some talks I gave:

Here are also some posters I made for conferences:

See also this article at the Gauss Centre for Supercomputing on our research using German supercomputers.

There is also a press release at HITS about the common envelope simulations and a corresponding Youtube video.

Moreover, I presented my research in a local TV programme (German only).

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Teaching.

Stellar structures, evolution, and explosions (WS 2016/2017)

Prof. Dr. F. Röpke, L. Horst, Dr. P. Edelmann, Dr. S. Jones, Dr. S. Ohlmann
(University of Heidelberg)

For more information, see the teaching page of the PSO group at HITS.

Computational Astrophysics (SS 2015)

Prof. Dr. F. Röpke, Dr. P. Edelmann, S. Ohlmann
(University of Heidelberg)
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Lecture: Monday, 14-16h, Philosophenweg 12, kl. HS
Tutorial: (Every second) Monday, 16-18h, Philosophenweg 12, CIP-Pool

Syllabus

The subject of astrophysics are complex objects and phenomena. Seeking for a theoretical understanding, a realistic description is required. To this end, computers have become a major tool of research and with ever more powerful computational resources and modern numerical techniques, a detailed modeling of astrophysical objects has become feasible. Based on general strategies to numerically model astrophysical phenomena, the course aims at describing some recent developments in computational astrophysics.

Further Material

Further material (homework problems, slides) are available at the teaching page of the PSO group at HITS.

Theoretische Astrophysik (SS 2014)

Prof. Dr. F. Röpke, S. Ohlmann
(University of Würzburg)
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Vorlesung: Freitag, 12-14 Uhr, Seminarraum 31.00.017
Übung: Dienstag, 10-12 Uhr, Seminarraum 31.00.017

Weitere Vorlesungsinformationen.

Am Dienstag, den 15.04.14, wird eine Vorlesung stattfinden. Die erste Übung wird am Dienstag, den 29.04.14 stattfinden.

Am Dienstag, den 17.6.14 findet eine Vorlesung statt, die Übung findet am 20.6. statt.

Am Dienstag, den 8.7.14 findet eine Vorlesung statt, die Übung findet am 11.7. statt.

Übungsblätter

Die Übungsblätter sind passwortgeschützt, die Zugangsdaten werden in der Vorlesung mitgeteilt werden.
Problem Set 1 Exercise on Tuesday, 29.04.2014
Problem Set 2 Exercise on Tuesday, 06.05.2014
Problem Set 3 (additional file: Lagrange.tar.gz) Exercise on Tuesday, 13.05.2014
Problem Set 4 Exercise on Tuesday, 20.05.2014
Problem Set 5 Exercise on Tuesday, 03.06.2014
Problem Set 6 Exercise on Friday, 20.06.2014
Problem Set 7 Exercise on Tuesday, 24.06.2014
Problem Set 8 Exercise on Tuesday, 01.07.2014
Problem Set 9 Exercise on Friday, 11.07.2014

Zusammenfassung

Das Ziel dieser Vorlesung ist ein besseres Verständnis der Aspekte der theoretischen Physik, die für astrophysikalische Phänomene wichtig sind. Dabei werden Methoden zur theoretischen Beschreibung der zugrundeliegenden Prozesse vermittelt und die entsprechenden Themen mit astrophysikalischen Beispielen veranschaulicht.

  • Überblick über die Beziehungen zwischen Forschungsgebieten der Astrophysik und den Hauptdisziplinen der Physik
  • Himmelsmechanik
  • Statistische Physik, Thermodynamik und astrophysikalische Zustandsgleichungen
  • Grundlagen der Sternstruktur und -entwicklung
  • Grundlagen des Strahlungstransports
  • Grundlagen der Hydrodynamik, Flussunstetigkeiten und -instabilitäten
  • Dynamische Phänomene in der Astrophysik: Weiße Zwerge, Chandrasekhar-Masse und thermonukleare Supernovae; Gravitationskollaps, Neutronensterne und Neutrinogetriebene Supernovae

Prüfung

Am Ende des Semesters wird eine mündliche Prüfung stattfinden. Voraussetzung zur Teilnahme an der Prüfung sind 50% gelöste Aufgaben in der Übung.

Weitere Informationen

Hier gibt es die Folien zur Vorlesung.
Weiteres Material, wie z.B. Skripte und Vorlesungsfolien finden Sie auf Prof. Röpkes homepage.

Computational Astrophysics (WS 2013/2014)

Prof. Dr. F. Röpke, Prof. Dr. C. Klingenberg, S. Ohlmann
(University of Würzburg)
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Lecture: Thursday, 10-12h, seminar room 31.01.008
Tutorial: Tuesday, 10-12h, seminar room 31.01.008

The next lecture will be on Thursday, 24.10.2013.

Syllabus

The subject of astrophysics are complex objects and phenomena. Seeking for a theoretical understanding, a realistic description is required. To this end, computers have become a major tool of research and with ever more powerful computational resources and modern numerical techniques, a detailed modeling of astrophysical objects has become feasible. Based on general strategies to numerically model astrophysical phenomena, the course aims at describing some recent developments in computational astrophysics.

Examination

At the end of the semester, an oral examination will be conducted. The prerequisite for taking the examination is reaching 50% solved homework problems compared to the total number of homework problems.

The material for the examination includes in the slides from Prof. Röpke everything up to SPH and the slides from Prof. Klingenberg without MHD.

Problem Sets

In order to download the problem sets, you need a password which is provided in the lecture.
Set 1 Tutorial on Tuesday, 29.10.2013 Hand in until Monday, 28.10.2013, 12pm
Set 2 Tutorial on Tuesday, 5.11.2013 Hand in until Monday, 4.11.2013, 12pm
Set 3 Tutorial on Tuesday, 12.11.2013 Hand in until Monday, 11.11.2013, 12pm
Set 4 Tutorial on Tuesday, 26.11.2013 Hand in until Monday, 25.11.2013, 12pm
Set 5 Tutorial on Tuesday, 03.12.2013 Hand in until Monday, 02.12.2013, 12pm
Set 6 Tutorial on Tuesday, 10.12.2013 Hand in until Monday, 9.12.2013, 12pm
Set 7 Tutorial on Tuesday, 16.12.2013 Hand in until Monday, 17.12.2013, 12pm
Set 8 Tutorial on Tuesday, 21.01.2014 Hand in until Monday, 20.01.2014, 12pm
Set 9 Tutorial on Tuesday, 28.01.2014 Hand in until Monday, 27.01.2014, 12pm

Further Material

There is a lecture information sheet available. Further material, e.g. scripts and lecture slides, are available from Prof. Röpke's homepage.

Older lectures

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Contact me.

Sebastian Ohlmann
Max Planck Computing and Data Facility
Gießenbachstr. 2
85748 Garching
Germany

Phone: +49 (0)89 – 3299 – 1144

Email: sebastian.ohlmann # mpcdf.mpg.de (replace # with @)