Gravitational Theory

Accretion disk around black hole

We study the motion of light, particles, and fluids close to black holes or neutron stars (image credit: James et al., CQG 32 (2015))

© Image by Oliver James, Eugénie von Tunzelmann, Paul Franklin and Kip S Thorne, Gravitational lensing by spinning black holes in astrophysics, and in the movie Interstellar, Classical and Quantum Gravity, Volume 32, Number 6 (2015). DOI 10.1088/0264-9381/32/6/065001. Used under license CC-BY-3.0

Clocks on different heights in gravity field

Gravity influences the ticking of clocks. Therefore clocks can measure heights!

Content of the Universe

The Universe is mostly unknown! We are interested in modified/alternative theories of gravity and electrodynamics to find explanations. Image credit: Wolz, PhD thesis 2022

Accretion disk around black hole
Clocks on different heights in gravity field
Content of the Universe

ABOUT OUR RESEARCH

Our research is focused on general relativity and its applications in astrophysics and geodesy as well as relations to quantum physics. This includes astrophysical extreme mass ratio systems and accretion disks around black holes as well as investigations of relativistic effects on the motion of satellites. The relativistic effects in rates of clocks on Earth and in space are crucial e.g. for height determination in geodesy. Moreover, we study fundamental problems in electrodynamics and in alternative theories of gravity.

Our fields of research

Dynamics of light, particles (stars), and fluids in relativistic spacetimes using mostly analytical techniques
Applications in relativistic astrophysics: extreme mass ratio systems, pulsar timing, accretion disks, gravitational lensing
Tests of gravity: investigation of relativistic effects on satellites orbiting the Earth as well as Earth- or space-based clocks
Relativistic geodesy: basic notions in General Relativity (GR), new concepts using the additional gravity degrees of freedom in GR; related topics are synchronisation and geodetic reference frames
Alternative/modified theories of gravity and electrodynamics

CONTACT

PD Dr. Eva Hackmann

+49 421 218 - 57862

eva.hackmann

Cluster of Excellence 'QuantumFrontiers'

The QuantumFrontiers program explores light and matter at the quantum frontier, advancing quantum and nanometrology to enhance measurement precision. These innovations enable groundbreaking technologies, from probing gravitational waves to understanding quantum-scale phenomena, deepening our knowledge of nature at both cosmic and microscopic scales.

Collaborative Research Center 'TerraQ - Relativistic and Quantum-based Geodesy'

The long term vision of TerraQ is to create a new geodesy based on quantum physics and general relativity, enabling unique prospects for satellite geodesy, gravimetric Earth observation and reference systems.

Research Unit 'Clock Metrology: A Novel Approach to TIME in Geodesy'

This research unit develops methods to enhance geodetic reference systems by linking all space geodetic techniques to a common time system. Accurate, stable global reference frames are essential for positioning, navigation, and understanding long-term geodynamic and climate processes, including plate tectonics and sea-level change.

Cost Action 23130 - Bridging high and low energies in search of quantum gravity (BridgeQG)

This COST Action Network brings together theorists and experimentalists to explore the regime where gravity meets quantum physics. From astrophysical observations to precision table-top experiments, the aim is to understand Planck-scale effects and study gravity's influence on quantum systems, bridging expertise in quantum-gravity, -optics, -mechanics, and high-energy astrophysics.

DFG Project 'Momentum dependent spacetime geometries: Traces of quantum gravity and fields in media'

This project establishes a rigorous mathematical framework for effective quantum spacetime geometries using Finsler and Hamilton geometry. It seeks to derive observable predictions (e.g., particle trajectories, time delays, light deflections), study classical and quantum field propagation on quantum spacetime, and develops the dynamics that determine the quantum spacetime geometry.

DFG project: General relativistic theory of charged accretion disk structures around black holes: influence of the (self)-electromagnetic interaction

Accretion disks around black holes and neutron stars, shaped by electromagnetic fields, provide insights into strong-gravity regimes. This project explores charged fluid disks, focusing on their self-interactions through analytic models and GRMHD simulations, aiming to unravel complex phenomena in disk structure, physics, and evolution near compact objects.

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PD Dr. Eva Hackmann

Head of the research group

+49 421 218 - 57862

eva.hackmann

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Dr. Christian Pfeifer

Researcher

+49 421 218 - 57837

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Dr. Dennis Philipp

Researcher

+49 421 218 - 57845

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Dr. Audrey Trova

Researcher

+49 421 218 - 57856

audrey.trova

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Jan Patrick Hackstein

Researcher

+49 421 218 - 57829

jan.hackstein

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Altin Shala

Researcher

+49 421 218 - 57873

altin.shala

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Felix Willenborg

Researcher

+49 421 218 - 57948

felix.willenborg

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Marian Cepok

Researcher

+49 421 218 - 57950

marian.cepok

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Bennet Grützner

Researcher

+49 421 218 - 57843

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Dr. Dennis Rätzel

Researcher

+49 421 218 - 57935

dennis.raetzel

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Dr. Shokoufeh Faraji

Visiting researcher

shokoufe.faraji

The list below shows the latest 25 publications of this research group. For the complete, searchable list of ZARM publications, please click more

2016

Obukhov, Y. N.; Puetzfeld, Dirk
Dynamics of test bodies in scalar-tensor theory and equivalence principle
Gravitation, Astrophysics, and Cosmology - Proceedings of the Twelfth Asia-Pacific International Conference, Moscow, 28 Jun - 5 July 2015, Eds. V. Melnikov and J.-P. Hsu, World Scientific (Singapore), 2016, pp. 231-235
2016

DOI: 10.1142/9789814759816_0043

File: http://arxiv.org/abs/1603.09106

Puetzfeld, Dirk; Obukhov, Y. N.
Generalized deviation equation and determination of the curvature in General Relativity
Phys. Rev. D, 93 :044073
2016

DOI: 10.1103/PhysRevD.93.044073

File: http://arxiv.org/abs/1511.08465

Schellstede, G. O.; Perlick, V.; Lämmerzahl, C.
On causality in nonlinear vacuum electrodynamics of the Plebanski class
Ann. Phys. (Berlin), 528 :738–749
2016

Tsupko, O. Yu.; Bisnovatyi-Kogan, G. S.; Jefremov, P. I.
Parameters of innermost stable circular orbits of spinning test particles: Numerical and analytical calculations
Gravitation and Cosmology, 22 :138-147
2016

Gomez, L. Gabriel; Arguelles, C. R.; Perlick, Volker; Rueda, J. A.; Ruffini, R.
Strong lensing by fermionic dark matter in galaxies
Phys. Rev. D, 94 :123004
2016

Grenzebach, A.
The shadow of black holes
2016

2015

Puetzfeld, Dirk; Obukhov, Y. N.
Equivalence principle in scalar-tensor gravity
Phys. Rev. D, 92 :081502(R)
2015

DOI: 10.1103/PhysRevD.92.081502

File: http://arxiv.org/abs/1505.01285

Perlick, V.; Tsupko, O. Yu.; Bisnovatyi-Kogan, Gennady S.
Influence of a plasma on the shadow of a spherically symmetric black hole
Phys. Rev. D, 92 :104031
2015

Obukhov, Y. N.; Portales-Oliva, F.; Puetzfeld, D.; Rubilar, G. F.
Invariant conserved currents in generalized gravity
Phys. Rev. D, 92 :104010
2015

DOI: 10.1103/PhysRevD.92.104010

File: http://arxiv.org/abs/1507.02191

Kunst, D.; Perlick, V.; Lämmerzahl, C.
Isofrequency pairing of spinning particles in Schwarzschild-de Sitter spacetime
Phys. Rev. D, 92 :024029
2015

Britzen, S.; Eckart, A.; Lämmerzahl, C.; Roland, J.; Brockamp, M.; Hackmann, E.; Kunz, J.; Macias, A.; Malchow, R.; Sabha, N.; Shahzamanian, B.
Jet signatures of black holes: From Sgr A* to active galactic nuclei
Astron. Nachr., 336 :471
2015

Garcia, A.; Hackmann, E.; Kunz, J.; Lämmerzahl, C.; Macias, A.
Motion of test particles in a regular black hole space–time
J. Math. Phys., 56 :032501
2015

Obukhov, Y. N.; Puetzfeld, Dirk
Multipolar test body equations of motion in generalized gravity theories
"Equations of Motion in Relativistic Gravity", D. Puetzfeld et. al. (eds.), Fundamental theories of Physics 179, pages 67-119, Springer 2015
2015

DOI: 10.1007/978-3-319-18335-0

ISBN: 978-3-319-18334-3

File: http://arxiv.org/abs/1505.01680

Gratus, J.; Perlick, V.; Tucker, R.
On the self-force in Bopp-Podolsky electrodynamics
J. Phys. A, 48 :435401
2015

Grenzebach, A.; Perlick, V.; Lämmerzahl, C.
Photon regions and shadows of accelerated black holes
Int. J. Mod. Phys. D, 24 :1542024
2015

Philipp, D.; Perlick, V.
Schwarzschild radial perturbations in Eddington-Finkelstein and Painlevé-Gullstrand coordinates
Int. J. Mod. Phys. D, 24 :1542006
2015

Schellstede, G.; Perlick, V.; Lämmerzahl, C.
Testing non-linear vacuum electrodynamics with Michelson interferometry
Phys. Rev. D, 92 :025039
2015

Eckart, A.; Britzen, S.; Valencia-S., M.; Straubmeier, C.; Zensus, J. A.; Karas, V.; Kunneriath, D.; Alberdi, A.; Sabha, N.; Schoedel, R.; Puetzfeld, D.
The galactic center black hole laboratory
"Equations of Motion in Relativistic Gravity", D. Puetzfeld et. al. (eds.), Fundamental theories of Physics, 179, pages 759-781, Springer 2015
2015

DOI: 10.1007/978-3-319-18335-0

ISBN: 978-3-319-18334-3

File: http://arxiv.org/abs/1501.02171

2014

Obukhov, Y. N.; Puetzfeld, D.
Conservation laws and covariant equations of motion for spinning particles
Proceedings of XV Advanced Research Workshop on High Energy Spin Physics "DSPIN-13", Dubna, 8-12 October 2013, Eds. A.V. Efremov and S.V. Goloskokov (Joint Inst. Nucl. Res., JINR, Dubna, 2014) p. 110-115
2014

File: http://arxiv.org/abs/1509.05900

Obukhov, Y. N.; Puetzfeld, Dirk
Conservation laws in gravity: A unified framework
Phys. Rev. D, 90 :024004
2014

DOI: 10.1103/PhysRevD.90.024004

File: http://arxiv.org/abs/1405.4003

Puetzfeld, Dirk; Obukhov, Y. N.
Equations of motion in metric-affine gravity: a covariant unified framework
Phys. Rev. D, 90 :084034
2014

DOI: 10.1103/PhysRevD.90.084034

File: http://arxiv.org/abs/1408.5669

Obukhov, Y. N.; Puetzfeld, Dirk
Equations of motion in scalar-tensor theories of gravity: A covariant multipolar approach
Phys. Rev. D, 90 :104041
2014

DOI: 10.1103/PhysRevD.90.104041

File: http://arxiv.org/abs/1404.6977

Itin, Y.; Lämmerzahl, C.; Perlick, V.
Finsler-type modification of the Coulomb law
Phys. Rev. D, 90 :124057
2014

DOI: 10.1103/PhysRevD.90.124057

Hackmann, E.; Lämmerzahl, C.
Generalized gravitomagnetic clock effect
Phys. Rev. D, 90 :044059
2014

DOI: 10.1103/PhysRevD.90.044059

File: http://arxiv.org/abs/arXiv:1406.6232

Hackmann, E.; Lämmerzahl, C.; Obukhov, Y. N.; Puetzfeld, D.; Schaffer, I.
Motion of spinning test bodies in Kerr spacetime
Phys. Rev. D, 90 :064035
2014

DOI: 10.1103/PhysRevD.90.064035

File: http://arxiv.org/abs/arXiv:1408.1773

Gravitational Theory

Accretion disk around black hole

Clocks on different heights in gravity field

Content of the Universe

ABOUT OUR RESEARCH

Our fields of research

CONTACT

Cluster of Excellence 'QuantumFrontiers'

Collaborative Research Center 'TerraQ - Relativistic and Quantum-based Geodesy'

Research Unit 'Clock Metrology: A Novel Approach to TIME in Geodesy'

Cost Action 23130 - Bridging high and low energies in search of quantum gravity (BridgeQG)

DFG Project 'Momentum dependent spacetime geometries: Traces of quantum gravity and fields in media'

DFG project: General relativistic theory of charged accretion disk structures around black holes: influence of the (self)-electromagnetic interaction

2016

2015

2014

Contact

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