Past Events 2017
December 2017
15. December 2017 - Bremen-Oldenburg relativity seminar
14. December 2017 - Physical Colloquium
November 2017
21. November 2017 - WORKSHOP - Geodäsie im Fallturm / Geodesy in the Drop Tower
20. November 2017 - TALK - She talks
October 2017
23 - 27 October 2017
SEMINAR
Fundamental Physics in Space
The 656th WE-Heraeus-Seminar on "Fundamental Physics in Space" is kindly funded by the Wilhelm and Else Heraeus Foundation Wilhelm and Else Heraeus Foundation and will be held October 23 - 27, 2017 in Bremen, Germany. With a lot of university based space research, a number of space institutes and large space industry, Bremen is one major space location in Europe.
At the moment there are comparably many fundamental physics space mission under way. LISA Pathfinder workes perfectly and the mission will terminate in a few weeks, MICROSCOPE is at the moment testing the Equivalence Principle in space and the first data have already been analyzed, since 2011 LARES is taking data in order to obtain in a few years an improved confirmation of the general relativistic Lense-Thirring effect, at the beginning of this year MAIUS made the first Bose-Einstein condensate in space, QUESS established the entanglement between quantum systems in space and on ground, the reading of the clocks of Galileo 5 and 6 are presently analyzed for performing a new test of the gravitational redshift, high precision clocks of ACES/PHARAO will be brought to the ISS for fundamental pyhsics and technology tests, and GRACE Follow On is also planned to be launched next year for measuring the gravitational field of the Earth to be used for geodesy but potentially also for fundamental tests.
Due to these activities it seems to be appropriate and timely to give an overall status report of Fundamental Physics in Space, to discuss and assess present science questions and whether it is of use that they might be tested in space, and to discuss newly developed space technologies. We will also highlight space based Earth observation, geodesy, and positioning. Accordingly, in our seminar we will treat
- past and present fundamental physics missions and missions under development
- the big science questions
- the advantage of space conditions
- new developments in space technology
- proposals for new Fundamental Physics missions
The program consists of invited as well as contributed talks and posters. We particularly encourage female scientist to contribute to the seminar. For young scientists we will award the best poster with a price.
More information here
16. October 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | University of Bremen, ZARM, Room 1280 |
| When: | 16:00 - 17:00 |
| Speaker: | Dr Oleg Yu. Tsupko (Space Research Institute of Russian Academy of Sciences) |
| Title: | Influence of plasma on the black hole shadow: analytical approach (Co-Authors: Volker Perlick and Gennady S. Bisnovatyi-Kogan) |
| Abstract: | The influence of a plasma around a black hole on the black hole shadow is discussed. Whereas modelling is made by many groups, we perform the first attempt to investigate the shadow in matter based on analytical calculations. We work in the frame of geometrical optics and take into account effects of general relativity and plasma presence. First of all, we consider general spherically symmetric space-time, and spherically symmetric distribution of plasma. Our main result for this case is an analytical formula for the angular size of the shadow of the black hole surrounded by plasma. As a plasma is a dispersive medium, the radius of the shadow depends on the photon frequency. The effect of the plasma presence is significant only in the radio regime. We find that for an observer far away from the black hole, the non-homogeneous plasma has a decreasing effect on the size of the shadow. Then, we consider the shadow of a Kerr black hole surrounded by a plasma. We have demonstrated that the Hamilton-Jacobi equation is separable, i.e., that a generalized Carter constant exists, only for special distributions of the plasma electron density. The necessary and sufficient condition for separability is found. We have derived analytical formulas for the boundary curve of the shadow on the observer’s sky in terms of two angular celestial coordinates. Examples of the shadow for different density distributions are constructed. Additionally, in this talk we would like to present our recent results about the fully analytical calculation of spin via deformation of the shadow, for the Kerr black hole in vacuum. We succeed to find compact analytical expressions which allow one to easily extract the black hole spin from observations of its shadow, without need to construct or model the entire curve of the shadow. References: 1. V. Perlick, O.Yu. Tsupko and G.S. Bisnovatyi-Kogan, Physical Review D 92, 104031 (2015) 2. V. Perlick and O.Yu. Tsupko, Physical Review D 95, 104003 (2017) 3. O.Yu. Tsupko, Physical Review D 95, 104058 (2017) |
12 - 13 October 2017
SYMPOSIUM
WoCaNet 2017
Where: Max Planck Institute for Biophysical Chemistry in Göttingen
The symposium aims to attract young scientists with inspiring lectures, plenary discussions and a career fair where young researchers can explore different career options and establish important contacts to promote their career path. With this symposium, we primarily want to address female scientists, but men are also welcome to join the discussions and learn about different career pathways.
Register at www.wocanet.uni-goettingen.de – the registration is closing soon! Registration deadline for the symposium and the networking dinner is 15th September 2017.
11 - 13 October 2017
WORKSHOP
RTG Autumn Workshop
Location: Oldenburg, Room V02 0-003
Confirmed speakers:
- Gennady S. Bisnovatyi-Kogan (Space Research Institute of the Russian Academy of Sciences, Moscow, Russia) - "Gravitational waves and core-collapsed supernovae"
- Eugenia Boffo (Jacobs University Bremen) - "Generalized Geometry in Models of Gravity"
- Yves Brihaye (University of Mons, Belgium) - “Spinning hairy black holes in five dimensions”
- Carla Cederbaum (University of Tübingen) - "Static, equipotential photon surfaces have no hair"
- Lucas Gardai Collodel (University of Oldenburg) - " Excited Boson Stars"
- Ludovic Ducobu (University of Mons, Belgium) - “Slowly rotating neutron stars in Horndeski gravity”
- Wolfgang J. Duschl (University of Kiel) - "AGN surveys - The Inverse Problem"
- Christian Knoll (University of Oldenburg) - “Slowly damped quasinormal modes of the massive Dirac field in d-dimensional Schwarzschild-Tangherlini spacetimes”
- Roman Konoplya (Silesian University in Opava Czech Republic) - "Are eikonal quasinormal modes linked to the unstable circular null geodesics?"
- Francesca Moglia (DESY, Hamburg) - "A European project supporting equal opportunities for women and men in physics"
- Piero Nicolini (Frankfurt Institute for Advanced Studies) - "Planck scale black hole engineering"
- Eugen Radu (Departamento de Física da Universidade de Aveiro and CIDMA, Portugal) - "Einstein–Maxwell–Anti-de-Sitter solitons and black holes"
- Maria Rodriguez (MPI for Gravitational Physics (Albert Einstein Institute)) - "Blandford-Znajek process in vacuo and its holographic dual"
- Rula Tabbash (University of Hamburg) - "The Hierarchy Problem within models of Large Extra Dimensions"
The program can be found here.
September 2017
28 September - 01 October 2017
CONFERENCE
21st German Conference of Women in Physics
| Where: | Ilmenau |
Further Information can be found here
4. - 15. September
SUMMER SCHOOL
The 23rd “Saalburg” Summer School
| Where: | Wolfersdorf, Thüringen |
| When: | From afternoon of Sunday, 04.09.16 to afternoon of Friday, 16.09.16 |
| Participants: | Up to 35 PhD students |
| Cost: | Travel plus 150 Euro |
| Deadline: | 30 June 2017 |
| Topic: | The school focuses on quantum field theory, particle physics and (quantum) gravity, but other related areas of theoretical and mathematical physics (e.g. aspects of string theory, condensed matter physics, quantum information) also receive attention. |
| Lecturer 1: | M. Bañados (Santiago de Chile) - Three dimensional gravity |
| Lecturer 2: | L. Covi (Göttingen) - Dark matter, baryogenesis and all that |
| Lecturer 3: | J. de Boer (Amsterdam) - Entanglement |
| Lecturer 4: | R. Durrer (Geneva) - Cosmology, where smallest and largest scales meet M. Serone (SISSA, Trieste) Exact perturbation theory |
The idea of this summer school is to learn new and old methods relevant to modern theoretical physics, formal as well as phenomenological. This is important especially for soon-to-be postdocs who need to broaden their view and skills in order to be competitive and versatile in changing collaborations. The aim of the school is to provide first hands-on experience with those topics. Accordingly, special emphasis is placed on exercises in small groups, complementing three hours of morning lectures. In the afternoon, the lecturers guide the students through a set of exemplary problems, which illustrate and expand on the main points of the lectures. The atmosphere is informal and lively discussions are encouraged.
Organized by Arthur Hebecker (Ruprecht-Karls-Universität Heidelberg), Ivo Sachs (Ludwig-Maximilians-Universität München), Stefan Theisen (Albert-Einstein-Institut Potsdam) and Olaf Lechtenfeld (Leibniz Universität Hannover).
Further information can be found here.
July 2017
24 - 28 July 2017
EXTERNAL EVENT
The 3rd Karl Schwarzschild Meeting
| Where: | Frankfurt, Germany |
| What: | This meeting will cover several aspects of black hole physics, gravitational waves and gauge gravity duality. There are several plenary sessions (Senior, Junior, Student) planned, with a special focus on the collaboration between young generations and experienced scientists. |
18 - 27 July 2017
SUMMER SCHOOL
The Dusty Universe
| Where: | Alpbach, Austria |
| Application deadline: | 31 March 2017 |
This year, sixty European engineering and science students will be chosen to participate in the 41st Summer School Alpbach, a ten day learning opportunity held in the beautiful Austrian Alps. Participants will be engaged in an in-depth learning experience. Over ten days they will attend stimulating lectures on various aspects of space science and engineering and will work intensely within smaller groups to define and design a space mission under the supervision of noted scientific and engineering experts within the field.
The topic of the Summer School Alpbach 2017 is “Dust in the Universe”. Understanding dust, its role in and use as a diagnostic for cosmic evolution has tremendously benefited from space missions covering the electromagnetic spectrum from X-rays to mm wavelengths, and will do so in the future.
Further information can be found here.
05. July 2017
RTG Colloquium
Where: University of Bremen, ZARM
Talk 1: Mariafelicia de Laurentis (Goethe University Frankfurt) "Exploring Gravity at Galactic Center" - Abstract
Talk 2: Annette Eicker (HafenCity University Hamburg) "The attraction of water - Using GRACE stallite gravity data to improve our understanding of the global water cycle" - Abstract
Talk 3: Lisa Wörner (ZARM, University of Bremen) "Exploring the Limits of Quantum Mechanics" - Abstract
Student's Seminar: Zahra Motahar (University of Oldenburg) "Neutron stars in scalar tensor theory"
Journals’ Club: Dennis Philipp (ZARM, University of Bremen) Paper by H. Quevedo, "Exterior and interior metrics with quadrupole moment", arXiv:1003.4344 [gr-qc] - Abstract
A preliminary program can be found here.
June 2017
13. June 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
First talk:
| Location: | University of Bremen, ZARM, Room 1280 |
| When: | 14:30 - 15:30 |
| Speaker: | Dr. Norman Guerlebeck (ZARM, University of Bremen) |
| Title: | The Meissner Effect for Isolated Horizons |
| Abstract: | Black holes are important astrophysical objects describing an end state of stellar evolution. There are theoretical predictions that Kerr black holes with high spins expel magnetic fields. Analogously to a similar property of superconductors, this is called Meissner effect. However, Kerr black holes are pure vacuum solutions, which do not include, e.g., accretion disks, which are essential for many observational techniques. Moreover, previous investigations are mainly limited to weak magnetic fields. By employing the formalism of weakly isolated horizons, we will be able to study generic rapidly spinning black holes in equilibrium including those deformed by accretion disks or other matter. We show for such black holes that they expel even strong magnetic and electric fields. Thus, the Meissner effect is not specific to Kerr black holes but rather a property of any axisymmetric black hole in equilibrium. We assess shortly the impact on creation of jets by accreting black holes and compare these results with recent observations. |
Second talk:
| Location: | University of Bremen, ZARM, Room 1280 |
| When: | 15:30 - 16:30 |
| Speaker: | Dr. Audrey Trova (ZARM, University of Bremen) |
| Title: | Equilibrium configurations of rotating magnetized tori |
| Abstract: | Studies of equilibrium of toroidal structures of a perfect fluid are important to understand the physics of accretion disks in active galactic nuclei (AGN) and the dense self-gravitating tori around stellar mass black holes. I will present the equilibrium structures of rotating magnetized tori in the Newtonian regime and in the General Relativity framework with various assumptions. My main interest was about to study the impact of the self-gravity of such objects and the impact of the magnetic field on the morphology and existence of theses equilibrium configurations. For instance, the existence of these solutions is possible for certain values of the model parameters, such as the rotation law, the polytropic index and the magnetic field intensity. |
09. June 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | Room W2 1-143, University of Oldenburg |
| When: | 14:15 |
| Speaker: | Prof. Panayotis Kevrekidis (Dept. of Mathematics & Statistics, UMass, Amherst) |
| Title: | Existence, Stability and Dynamics of Solitary Waves, Vortices and Vortex Rings in Bose-Einstein Condensates: From Theory to Experiments |
| Abstract: | In this talk, we will present an overview of some of our recent theoretical, numerical and experimental efforts concerning the static, stability, bifurcation and dynamic properties of coherent structures that can emerge in one- and higher-dimensional settings within Bose-Einstein condensates. We will discuss how this ultracold setting can be approximated at a mean-field level by a deterministic PDE of the nonlinear Schrodinger type and what the fundamental nonlinear waves of the latter are, such as dark solitons (in 1d) and vortices (in 2d), as well as vortex lines and rings (in 3d). Then, we will try to go to a further layer of simplified description via nonlinear ODEs encompassing the dynamics of the waves within the traps that confine them, and the interactions between them. Finally, we will attempt to compare the analytical and numerical implementation of these reduced descriptions to recent experimental results and speculate towards a number of interesting possibilities for the future. |
May 2017
31. May 2017
RTG Colloquium
Where: Leibniz Universität Hannover
Talk 1: Nadine Neumayer (MPI for Astronomy, Heidelberg) "The build-up of galactic centers - how do black holes get there?" - Abstract
Talk 2: Anupam Mazumdar (Van Swinderen Institute, University of Groningen) "Constructing Universal Laws of Gravity at Short distances and Small time scales" - Abstract
Journals’ Club: Paul Jefremov (ZARM, University of Bremen) "Exact solutions to force-free electrodynamics in black hole backgrounds" by T. D. Brennan, S. E. Gralla and T. Jacobson, CQG, Vol. 30 19 (2013)
Student's Seminar: Vojtech Witzany (ZARM, University of Bremen) "Generalized conservation law near spinning black holes" - Abstract
A preliminary program can be found here.
23. May 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | ZARM, Room 1280, University of Bremen |
| When: | 16:15 |
| Speaker: | Roberto Tanzi |
| Title: | Quantum signatures of non-metric geometries |
| Abstract: | Ray optics effectively fail to detect an eleven-parameter family of deviations from a metric spacetime geometry. I show that, however, these ray-optically invisible deviations are detectable in quantum electrodynamics scattering amplitudes and I provide few examples. |
23. May 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | ZARM, Room 1280, University of Bremen |
| When: | 14:30 |
| Speaker: | Claudio Paganini (Albert-Einstein Institute, Golm) |
| Title: | The Fingerprints of Black Holes - Shadows and their Degeneracies |
| Abstract: | First I will introduce the concept of the shadow of a black hole and what it means for the shadows of two observers to be degenerate. I will then present preliminary results showing that no continuous degenerations exist between the shadows of observers at any point in the DOC of any Kerr-Newman-(anti)-De-Sitter black hole spacetime of unit mass. Therefore an observer can, by measuring the black holes shadow, in principle determine the angular momentum, the charge and the cosmological constant of the black hole under observation, as well as his radial distance from the black hole and his angle of elevation above the equatorial plane. |
19. May 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | ZARM, University of Bremen, Room 1280 |
| When: | 14:00 |
| Speaker: | Aleš Flandera (Charles University Prague) |
| Title: | Existence, Stability and Dynamics of Solitary Waves, Vortices and Vortex Rings in Bose-Einstein Condensates: From Theory to Experiments |
| Abstract: | We study the Kerr-Newman black hole in the formalism of weakly isolated horizons using a near horizon solution of Einstein’s equations in the Bondi-like coordinates employed by Krishnan in 2012. This solution establishes the existence of a null tetrad adapted to a non-twisting null congruence. However, the explicit construction of such a tetrad for the Kerr-Newman metric is not given. We formulate appropriate initial data and firstly construct the tetrad in a perturbative way in the neighbourhood of the horizon. Finally, we find also its exact form everywhere in the Kerr-Newman space-time. |
18 -19 May 2017
WORKSHOP
12. Kosmologietag
| Where: | Center for Interdisciplinary Research, ZiF at Bielefeld University |
| When: | Thursday after lunch till Friday noon |
| Registration fee: | 50,00 € |
The workshop consists of mainly contributed talks, complemented by invited overview talks. Submissions of a title for a contributed talk about any aspect of cosmology and gravity are welcome. Areas of cosmology which are expected to be covered include the CMB, HI abservations, large scale structure, dark matter, inflation, dark energy (and its alternatives) and baryo-/leptoggenesis.
Talks - with the exception of the overview talks - should last 15 minutes + 5 minutes discussion.
Further information can be found here.
5. May 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | University of Oldenburg, Campus Wechloy, Room W2 3-349 |
| When: | 15:15 |
| Speaker: | Dr. Ehsan Hatefi (TU Wien) |
| Title: | On DBI, Wess-Zumino effective actions of Superstring theories and their all order alpha. Corrections in IIB, IIA |
| Abstract: | In this seminar, We would like to talk about all kinds of effective actions in Type IIA, IIB super string theories,involving DBI,Chern-Simons and more importantly new Wess-Zumino actions. Indeed we try to provide a comprehensive explanation not only for BPS branes but also for D-brane-anti D-brane systems. Along those actions, we also introduce various new techniques for mathematicians/string theorists for which getting the exact and final form of the world sheet integrals up to five point mixed closed-open amplitudes to all orders will be presented. Eventually we make various remarks on how to derive without any ambiguity all order ?’ corrections to all type II effective actions. If time allows, we then mention several applications related to those effective actions as well. |
4. May 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | University of Oldenburg, Campus Wechloy, Room W2 3-349 |
| When: | 10:00 c.t. |
| Speaker: | Hendrik Neumann (University of Oldenburg) |
| Title: | Geodesics in the Myers-Perry-AdS spacetime |
| Abstract: | In this talk I consider the Myers Perry AdS black hole, which is characterized by its mass, two independent rotation parameters and a negative cosmological constant. First I discuss some properties of this solution, then I analyze the geodesic equations in this spacetime. I present the whole set of analytical solutions in terms of elliptic functions. With the help of parametric diagrams and effective potentials I discuss the possible orbits and show some example plots. |
03. May 2017
RTG Colloquium
| Where: | University of Oldenburg |
| When: | 3. May 2017 |
Talk 1: Troels Harmark (Niels Bohr Institute, Copenhagen, Denmark) - "Spin Matrix theory limit of the AdS/CFT correspondence" - Abstract
Talk 2: Ehsan Hatefi (Vienna University of Technology, Vienna Austria) - “Black hole formation and Critical Collapse in the Axion-Dilaton System in Diverse Dimensions” - Abstract
Student's Seminar: Dennis Philipp (University of Bremen) - "Timelike congruences, acceleration and redshift potential"
Journals’ Club: Xiao Yan Chew (University of Oldenburg) - “Spherical Photon Orbits Around a Kerr Black Hole”
The program can be found here.
April 2017
24 - 28 April 2017
SEMINAR
Do Black Holes Exist? - The Physics and Philosophy of Black Holes
| Where: | Bad Honnef, Germany |
| What: | The evidence for the existence of Black Holes received a strong boost with the direct detection of gravitational waves which perfectly fit to the simulation of the merger of two Black Holes with masses of around 30 to 40 Solar masses. Further evidence for their existence is given by the observation of stars around the Sagittarius A*, the center of our galaxy, the observation of radiation from accretion disks around many massive galactic Black Holes, high energetic jets emerging from the near vicinity of Black Holes. We are also waiting for further evidence based on new observations with the Event Horizon Telescope and the Black Hole Cam. However, despite these overwhelming observations there is still the question of the interpretation: How shall we deal with the situation that no Black Hole can be observed directly? This question will be discussed by experts from the observations, from the mathematical and theoretical aspects of Black Holes, as well as from the philosophy of sciences. |
Topics:
- the current status of observations and future plans
- Black Hole solutions of gravitational field equations and their properties
- Physical effects in the vicinity of Black Holes
- the philosophy of Black Holes
March 2017
13. - 17. March 2017
MEETING
DPG Spring Meeting
| Where: | University of Bremen, ZARM |
| When: | 13.03.2017 - 17.03.2017 |
DPG Frühjahrstagung (Spring Meeting) of the Matter and Cosmos Section (SMuK) with the divisions and working groups:
- Environmental Physics
- Short Time-scale Physics
- Extraterrestrial Physics, Gravitation and Relativity
together with the Astronomischen Gesellschaft e. V. - Theoretical and Mathematical Physics
- Working Group Philosophy of Physics
For more information please visit the meeting's website here.
9. March 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | University of Oldenburg, Campus Wechloy, Room W2 1-143 |
| When: | 11:15 |
| Speaker: | Dr. Kamal Hajian (Institute for Research in Fundamental Sciences Tehran, Iran) |
| Title: | A review on covariant phase space formulation |
| Abstract: | In this talk, after reviewing the phase space and its canonical construction, I construct step by step the covariant phase space formulation of gravitational theories. Covariant phase space formalism (also known as Wald formalism) yields a convenient method for calculating black hole conserved charges. |
6 - 7 March 2017
WORKSHOP
GRK Workshop Hannover
Confirmed speakers:
- Fabian Schmidt (MPA Garching) - IR modifications of gravity in cosmology - Abstract
- Klaus Dolag (MPA Garching) - Challenges for Cosmological Simulations
- Enrico Pajer (Utrecht) - A simpler universe - Abstract
- Lavinia Heisenberg (ETH Zürich) - Fundamental Fields of Gravity - Abstract
- Mihalis Dafermos (Cambridge University) - Abstract
- Torsten Asselmeyer-Maluga (DLR Berlin) - Exotic (Smooth) Black Holes: Exotic Smoothness and Black Holes - Abstract
- Neven Caplar (ETH Zürich) - Quantitative Evaluation of Gender Bias in Astronomical Publications from Citation Counts - Abstract
- Golam Shaifullah (University of Bielefeld) - Gravitational Quadrupole Emission in an MSP binary - Abstract
- Kamal Hajian (IPM, Tehran) - Dilaton moduli as redundant parameters - Abstract
- Jose Blazquez Salcedo (University of Oldenburg) - Quasi-normal modes of black holes in Einstein-Gauss-Bonnet-dilaton theory - Abstract
The program can be found here.
3. March 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
First talk:
| Location: | University of Bremen, TAB, Room 2.63 E (The building is next to the Drop Tower, on the other side of the street Am Fallturm. Enter from the side facing the Drop Tower (Entrance E), the room is on the second floor.) |
| When: | 11:00 |
| Speaker: | Alessandro Spallicci (University of Orleans, France) |
| Title: | Self-force and motion |
| Topic: | An overview of the concept of self-force in General Relativity is given, with some emphasis on the motion of compact stars captured by supermassive black holes. Later, we examine the concept of self-force in Newtonian gravity, the relation with the Equivalence Principle and what the outcome would be when dropping masses in an ideal ZARM-Pisa tower. |
Second talk:
| Location: | University of Bremen, ZARM, Room 1280 |
| When: | 14:00 |
| Speaker: | Luca Bonetti (University of Orleans, France) |
| Title: | Non-Mawellian electromagnetism in astrophysics and in space applications at low radio frequencies |
| Topic: | The universe is largely observed with electromagnetic signals – supposedly Maxwellian – though the gravitational wave window was just unbarred. Meanwhile, cosmology is since long confronted with an universe for 96% dark and unknown. Thus, it is pertinent for fundamental physics to start a theoretical and experimental verification of electromagnetism, and its photon messenger. This seminar discusses non-Maxwellian theories, focusing on testable effects. We deal with a range of applications and assess how alternative electromagnetic theories are helpful. We revise the most notable theories, either non-linear or massive. In the former class, for analysis of the self-force, we consider the radiation of an uniformly accelerating Born-Infeld charge; in the Heisenberg-Euler theory, we find a frequency shift induced by an overcritical magnetic dipole, associated to a magnetar. Being the photon the only massless particle in the Standard Model (SM), we explore SM extensions. Indeed for the massive class, in a supersymmetric context, we find non-Maxwellian behaviors arising in even and odd cases of Charge- Parity-Time Reversal (CPT) symmetry: either subluminal propagation or massive dispersive behavior proportional to the Lorentz symmetry breaking vector. Further on, we determine an upper mass limit of 3.2 x 10-50 kg by analyzing Fast Radio Bursts. Massive (à la de Broglie-Proca) photon arrival time delays go with the inverse of frequency squared, as photons passing through plasma. Thereby, our interest for low frequency radio-astronomy on ground or in space. An unexplored domain hiding pulsars lies below 15 MHz, and it will be accessible by a swarm of nano-satellites. |
02 March 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | University of Oldenburg, Campus Wechloy, Room W2 3-349 |
| When: | 16:15 |
| Speaker: | Dr. Kamal Hajian (Institute for Research in Fundamental Sciences Tehran, Iran) |
| Title: | From black hole information paradox to firewall paradox |
| Abstract: | Black hole information paradox has been a concomitant of realizing these objects/solutions as thermodynamic systems. The paradox can be explained as: in the semi-classical regime which gravity is dealt classically, black hole evaporation is not a unitary process. A famous resolution to this paradox was presented in 1993, which is called ``black hole complementarity". This resolution can be roughly explained as: the set of observers standing outside of the black hole and the set of observers falling freely into it, should be considered complement to each other. One can not see the world from the point of view of both sets of observers. Using this complementarity, the information paradox has been considered to be resolved. But, it has been shown that black hole complimentarity yields another paradox which is known as ``firewall paradox". In this talk, I will review the two paradoxes mentioned above. |
February 2017
28. February 2017
| Location: | ZARM, University of Bremen, Room 1280 |
| When: | 14:30 |
| Speaker: | Vittorio De Falco (ISSI, Bern, Switzerland) |
| Title: | Approximate analytical calculations of photon geodesics in the Schwarzschild metric |
| Topic: | In this talk, we show a method for deriving approximate analytical formulae. to integrate photon geodesics in a Schwarzschild spacetime. Based on this, we derive the approximate equations for light bending and propagation delay that have been introduced empirically already respectively by Beloborodov 2002 and Poutanen & Beloborodov 2006. We then derive for the first time an approximate analytical equation for the solid angle. We discuss the accuracy and range of applicability of the new equations and present a few simple applications of them to known astrophysical problems, that are: light curve from an emitting clump orbiting a black hole, emission line profile from an accretion disk around a black hole and light curve from a hot spot on the surface of a rotating neutron star. |
16 - 18 February 2017
SEMINAR
7th Central European Relativity Seminar 2017
| Where: | Bremen "Haus der Wissenschaften" - Sandstraße 4/5, 28195 Bremen, Olbers Saal, first floor |
| What: | This is the seventh seminar of a series initiated at the ESI (Vienna) January 27 - 29, 2011. This series of seminars is designed to provide a forum for younger researchers to present their work, and to expand their research horizons. The main geographical basin of attraction is Austria, the Czech Republic, Hungary, Poland and Germany. |
| Topics: | The scientific program will include keynote lectures by D. Giulini and C. Lämmerzahl, as well as seminars by young researchers selected on the basis of submitted abstracts. The speakers will be chosen mainly amongst graduate students and post-docs. Anticipated are about 24 talks of 20 minutes each. A few longer talks might replace some of the shorter ones if scientifically or pedagogically desirable. The seminar will be accompanied by a public lecture (in english) by Jochen Liske, Hamburger Sternwarte, Universität Hamburg, on 18.02.2017, 15.30, entitled: "The World's Largest Telescope and the Acceleration of the Universe" |
| Abstracts: | Abstracts submitted by January 15, 2017, will receive full consideration. Later submissions might be considered if the schedule allows. Abstract submission |
15. – 17. February 2017
CONFERENCE
The 8th edition of the annual Strings, Cosmology and Gravity Student Conference (SCGSC)
| Where: | Paris, Institut Henri Poincaré |
| When: | 15th and 17th of February 2017 |
| Registration deadline for speakers: | 31st of December 2016 |
| Registration fee: | None |
Registration to attend or speak is open at:
sites.google.com/site/scgscparis2017/home
Anyone interested in speaking at the conference should register by the 31st of December 2016 at the latest.
Due to a change in the funding circumstances an early registration deadline is no longer imposed: all applications to speak will be considered equally after the final deadline.
This conference is designed to bring together young PhD and early stage postdoctoral researchers working in theoretical high energy physics, especially in areas of string theory, cosmology, and gravity. The primary aim is to give attendants the opportunity to present their research via contributed talks and to form collaborations. There will be no registration fee, and the conference is open to all interested graduate students and postdoctoral researchers.
Contact: scgsc2017@gmail.com
9. - 10. February 2017
WORKSHOP
11th Nordic String Theory Meeting 2017
| When: | 09.02.17, after lunch - 10.02.17, afternoon |
| Where: | Leibniz Universität Hannover: Institut für Theoretische Physik, seminar rooms no. 267, 268, 269 on 3rd floor |
| Contact: | Olaf Lechtenfeld and Marco Zagermann |
This workshop continues the tradition of the annual Nordic String Theory Meetings. As in the past, the idea is to have a short but intense meeting of stringy people from "nordic" places Berlin (HU), Bremen (Jacobs), Copenhagen (NBI), Göttingen, Groningen, Hamburg (Uni/DESY), Hannover, Potsdam (AEI) and possibly some nordophilic people from not so nordic places.
Slides of the talks will available online (here)
Financial support for travel or accommodation is unfortunately not available.
Further information can be found here.
07. February 2017
RTG Colloquium
| When: | 07.02.2017, 10:30 - 17:30 hrs |
| Location: | University of Bielefeld, Rooms D6-135 and D6-136 |
| Talk 1: | Dr. Stanislav Babak (AEI, MPI for Gravitational Physics, Potsdam) - Universe in gravitational waves with Laser Interferometer Space Antenna |
| Talk 2: | Prof. Carsten van de Bruck (University of Sheffield) - Dark energy and new interactions in the dark sector |
| Student's Seminar: | Kai Flathmann (University of Oldenburg) - Analytic solutions of the geodesic equation for U(1)2 dyonic rotating black holes |
| Journals' Club: | Paul Jefremov (ZARM, University of Bremen) - Neutrino-cooled accretion disks around spinning black holes (Chen & Beloborodov, The Astrophysical Journal , 657:383-399, 2007) |
The program can be found here.
January 2017
25. January 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | ZARM, University of Bremen, Room 1280 |
| When: | 16:00 |
| Speaker: | Dr. Souvik Banerjee (Uppsala University) |
| Title: | 2. Lecture on Quantum Mechanics and General Relativity |
| Topic: | The second of two lectures on black holes, the black hole information paradox, in general on the conflict between GR and QM, locality, a possible resolution of the information paradox, and on some further recent developments. |
24. January 2017
BREMEN - OLDENBURG RELATIVITY SEMINAR
| Location: | ZARM, University of Bremen, Room 1280 |
| When: | 14:30 |
| Speaker: | Dr. Souvik Banerjee (Uppsala University) |
| Title: | 1. Lecture on Quantum Mechanics and General Relativity |
| Topic: | The first of two lectures on black holes, the black hole information paradox, in general on the conflict between GR and QM, locality, a possible resolution of the information paradox, and on some further recent developments. |
17 January 2017
WORKSHOP
Astronomie am Fallturm
| Where: | ZARM, University of Bremen |
| Speaker: | Dr. Tobias Illenseer, Universität Kiel |
| Title: | Der Einfluss von Selbstgravitation auf das Wachstum supermassereicher Schwarzer Löcher |
| Abstract: | |
| Speaker: | Dr.-Ing. Silvia Scheithauer, Max-Planck-Institut für Astronomie (MPIA), Heidelberg |
| Title: | Gravity CIAO - Instrumentierung am ESO Paranal Observatorium |
| Abstract: | Die ESO (European Southern Observatory) betreibt mehrere astronomische Observatorien in Chile, unter anderem das Very Large Telescope Interferometer (VLTI) auf dem Cerro Paranal. Die 14 ESO Mitgliedsstaaten - unter anderem Deutschland - sind für den Bau der astronomischen Instrumente zuständig. Seit 2015 wird dort das GRAVITY Instrument in Betrieb genommen: GRAVITY ist ein Nah-Infrarot-Instrument der zweiten Generation für das VLTI, welches das Licht der vier 8,2m-Teleskope miteinander kombiniert, um eine viel höhere Auflösung zu erreichen, als es mit einem einzigen Teleskop möglich wäre. Im Zentrum nahezu jeder größeren Galaxie finden wir supermassereiche Schwarze Löcher mit Massen von bis zu einigen 1010 Sonnenmassen. Wir gehen heutzutage davon aus, dass diese Schwarzen Löcher wie auch die sie umgebenden Galaxien eine kosmologische Entwicklung durchlaufen. Das bedeutet, dass große, massereiche Strukturen nicht einfach plötzlich nach dem Urknall vorhanden sind, sondern im frühen Universum entstehen und dann durch das Ansammeln von Materie (Akkretion) wachsen. Im Falle der supermassereichen Schwarzen Löcher ist dieser Akkretionsprozess direkt beobachtbar und steht im engen Zusammenhang mit dem Phänomen der Quasare und aktiven Galaxien. Der Vortrag wird einen allgemeinen Einblick in das Gebiet der Akkretionsphysik sowie der theoretischen Behandlung und numerischen Simulation sogenannter Akkretionsscheiben geben. Im Fokus stehen dabei Systeme, bei denen die Masse des zentralen Schwarzen Lochs deutlich geringer ist als die der sie umgebenden Materie. Es wird diskutiert inwieweit sich diese Systeme von den klassischen, nicht-selbstgravitierenden Modellen für Akkretionsscheiben unterscheiden. Dabei wird insbesondere die Frage erörtert, ob Modelle für selbstgravitierende Akkretionsscheiben das beobachtete Wachstumsverhalten von upermassereichen Schwarzen Löchern erklären können. |
10. January 2017
RTG Colloquium
| Where: | ZARM, University of Bremen |
| Speaker: | Carlos A.R. Herdeiro |
| Title: | Kerr black holes with bosonic hair: theory and phenomenology |
| Abstract: | Over the last two years it has been found that new classes of asymptotically flat black hole solutions, regular on and outside the event horizon, bifurcating from the vacuum Kerr solution, exist in General Relativity, with simple matter contents that obey all energy conditions, namely Kerr black holes with scalar hair and Proca hair. In this talk I will review the general mechanism that allows these solutions to exist, intimately connected to superradiance, how these solutions circumvent well known no-hair theorems and some of their phenomenology (shadows and x-ray spectra) which can be considerably distinct from that of Kerr. |
| Key references | C. Herdeiro, E. Radu: Kerr black holes with scalar hair, Phys. Rev. Lett. C. Herdeiro, E. Radu, H. Runarsson: Kerr black holes with Proca hair, Class. Quant. Grav. P. Cunha, C. Herdeiro, E. Radu, H. Runarsson: Shadows of Kerr black holes with scalar hair, Phys. Rev. Lett. |
| Speaker: | Gleb Arutyunov, II. Institute for Theoretical Physics, Hamburg University |
| Title: | Solution of N=4 super Yang-Mills theory via the Mirror TBA |
| Abstract: | How the Mirror Thermodynamic Bethe Ansatz approach solves for the spectrum of scaling dimensions of composite gauge-invariant operators in N=4 supersymmetric Yang-Mills theory. |
The program can be found here.
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