Relativistický seminář
Ústavu teoretické fyziky


Seminář se koná v úterý ve 13:10 v posluchárně ÚTF MFF UK
v 10. patře katedrové budovy v Tróji, V Holešovičkách 2, Praha 8


Příští semináře:

V nejbližší budoucnosti nejsou plánované žádné semináře.


Minulé semináře:

24. září 2013
Quintessence, phantom and frustrated network of topological defects at late stages of the Universe evolution
Alvina Burgazli
Odessa National University
(seminář v angličtině)

Deep inside the cell of uniformity and at late stages of the evolution, the Universe is filled with inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies). Supposing that the Universe contains also the cosmological constant and a perfect fluid with a negative constant equation of state parameter ω (e.g., quintessence, phantom or frustrated network of topological defects), we investigate scalar perturbations of the FRW metrics due to inhomogeneities. Our analysis shows that, to be compatible with the theory of scalar perturbations, this perfect fluid, first, should be clustered and, second, should have the equation of state parameter ω = −1/3 (in particular, this value corresponds to the frustrated network of cosmic strings). Therefore, the frustrated network of domain walls with ω = −2/3 is ruled out. A perfect fluid with ω = −1/3 neither accelerates nor decelerates the Universe. We also obtain the equation for the nonrelativistic gravitational potential created by a system of inhomogeneities. Due to the perfect fluid with ω = −1/3, the physically reasonable solutions take place for flat, open and closed Universes. This perfect fluid is concentrated around the inhomogeneities and results in screening of the gravitational potential.

8. října 2013
Action-angle variables and KAM-theory in general relativity
Daniela Kunst
Fundamental Physics Department, ZARM - Center of Applied Space Technology and Microgravity, University of Bremen
(seminář v angličtině)
15. října 2013
Geometrie v blízkosti horizontu
Jiří Daněk
ÚTF
22. října 2013
Interakce gravitačního záření s látkou ve vysokofrekvenčním přiblížení
Tomáš Tintěra
ÚTF
29. října 2013
Seminář se nekoná
5. listopadu 2013
Rotující částice v algebraicky speciálních prostoročasech
Milan Šrámek
ÚTF
12. listopadu 2013
Future stability of cosmological solutions without cosmological constant
dr. Ernesto Nungesser
Trinity College Dublin, School of Mathematics, Ireland
(seminář v angličtině)
19. listopadu 2013
Unimodular theory of gravity and its implications in cosmology
dr. Naveen K. Singh
Theory Division, Physical Research Laboratory, Navrangpura, Ahmedabad, India
(seminář v angličtině)
26. listopadu 2013
On the zeroth law of thermodynamics in Lanczos-Lovelock gravity
dr. Swastik Bhattacharya
Institute of Mathematical Sciences, Chennai, India
(seminář v angličtině)
3. prosince 2013
New exact solutions in a model of f(R) gravity
dr. Tayebeh Tahamtan
Department of Physics, Eastern Mediterranean University, North Cyprus
(seminář v angličtině)
10. prosince 2013
On black-hole no-hair theorems
dr. Sourav Bhattacharya
Department of Physics, Harish-Chandra Research Institute, Allahabad, India
(seminář v angličtině)
17. prosince 2013
Dynamics of spinning test bodies in general relativity - center of mass, momentum, and the problem of the representative worldline
dr. Luis Filipe Costa
Department of Mathematics, Institute of Advanced Technology, University of Lisboa, Portugal
(seminář v angličtině)
7. ledna 2014
Einstein-Cartan Theory - Kinematical Hilbert Space
dr. Marián Pilc
ÚTF
25. února 2014
(Re)constructing spherically symmetric metrics in general relativity
Sante Carloni
ÚTF

I present a general method to reconstruct spherically symmetric metrics in GR. The method is based on definition of some special scalar variables in the framework of the 1+1+2 covariant approach proposed by Ehlers and Ellis. It provides a new way to explore the properties of spherically symmetric metrics in GR. After explaining the scheme I will give some examples and show that the new technique is also applicable to modified gravity.

4. března 2014
On the existence and properties of helically symmetric systems
Martin Scholtz
ÚTF

We review our earlier work on the existence of periodic solutions of Einstein's equations and relate it to more recent results concerning the existence of spacetimes with helical symmetry in linearized gravity and electrodynamics. In addition we present a new calculation of Bondi mass for spacetimes with electromagnetic and scalar field sources.

11. března 2014
Algebraic structure of Kundt geometries in any dimension
Robert Švarc
ÚTF
18. března 2014
Spectral states of active galactic nuclei from simultaneous X-ray and UV measurements by XMM-Newton
Dr. Jiří Svoboda
Prague Relativistic Astrophysics Group, Astronomical Institute of the Czech Academy of Sciences

It is generally believed that the black holes in active galactic nuclei (AGNs) and X-ray binaries (XRBs) work in a similar way. While XRBs evolve rapidly and several sources have undergone a few complete cycles from quiescence to an outburst and back, AGNs remain in the same state due to their larger characteristic time-scale, proportional to their size. However, the study of AGN spectral states is still possible with a large sample of sources. Multiwavelength observations are needed for this purpose since the AGN thermal disc-emission dominates in the ultraviolet energy range while the up-scattered hot-corona emission is detected in X-rays. Based on ROSAT All-Sky Survey and SDSS database, Koerding et al. (2006) constructed the disc-fraction/luminosity diagrams of AGNs that revealed the analogy with the state diagrams of XRBs. I would like to present our results that are based on the comparison of strictly simultaneous UV and X-ray measurements of AGNs obtained with the XMM-Newton satellite.

25. března 2014
On non-linear electrodynamics: Einstein, Hoffmann, Born, Infeld, ...
Dr. Tayebeh Tahamtan
Department of Physics, Eastern Mediterranean University, North Cyprus
(seminář v angličtině)
1. dubna 2014
Geometric methods of constructing generic off-diagonal exact solutions in gravity
Prof. Sergiu Vacaru
Alexandru Ioan Cuza University, Iasi, Romania
(seminář v angličtině)
8. dubna 2014
Začne až ve 13:30!
The complex morphology of active galactic nuclei: where do we stand?
Dr. Frédéric Marin
Prague Relativistic Astrophysics Group, Astronomical Institute of the Czech Academy of Sciences
(seminář v angličtině)

The topic of active galactic nuclei (AGN) is wide, complex and multi-disciplinary. From their inner core where general and special relativity rule the accretion and emission mechanisms, to their external boundaries where classical physics and dusty mixtures prevail, explaining the intrinsic composition and morphology of AGN remains a major challenge due to the variety of their spectroscopic, timing and polarimetric signatures. Describing AGN using a unique picture is a rather challenging task, but a unified model has slowly emerged. A so far very successful theory predicts that most of the differences can be explained by an orientation effect: AGN properties differ if the system is seen from a polar, an intermediate or an equatorial inclination, the difference being attributed to circumnuclear obscuration. But does this geometrical arrangement solve everything ? In this seminar, I will review the current status of the unified model of AGN and explore, throughout spectroscopy and polarization, the successes and failures of all the existing models.

15. dubna 2014
Seminář se nekoná
22. dubna 2014
Seminář se nekoná
29. dubna 2014
PP-waves as non-Abelian duals of flat metric
prof. Ladislav Hlavatý
Katedra fyziky, FJFI ČVUT
(seminář v angličtině)
6. května 2014
Kinematical Hilbert space for Einstein-Cartan theory: Continuous tensor product and integral representation of fundamental variables
dr. Marián Pilc
UniCredit Bank
(seminář v angličtině)
13. května 2014
Scalar perturbations in f(R)-cosmology
Mgr. Jan Novák
Matematický ústav AV ČR
(seminář v angličtině)
20. května 2014
Effects of primordial curvature perturbations on the value of the cosmological constant
Prof. Antonio Enea Romano
Group of Phenomenology of Fundamental Interactions, University of Antioquia, Medellín / Yukawa Institute for Theoretical Physics, Kyoto University
(seminář v angličtině)
27. května 2014
Extended teleparallel gravities: general properties
Dr. Diego Saez Gomez
Department of Theoretical Physics and History of Science, Faculty of Science and Technology, University of Basque Country, Bilbao
(seminář v angličtině)

Teleparallel gravity is a gauge theory for the translation group defined in the tangent bundle of a Riemannian spacetime, where the so-called tetrad plays the role of the dynamical field of the theory and is parallely transported (absolute parallelism condition) by assuming the Weitzenböck connection instead of the Levi-Civita connection, leading to a non-null torsion but a null scalar curvature. Whereas teleparallel gravity is equivalent to general relativity, its extensions, also known as f(T) gravities in analogy to f(R) gravity, give rise to new features and interesting properties but are not equivalent to f(R) gravity. In this talk, I will review some of the last analysis about f(T) gravity, including the violation of the local Lorentz invariance, the construction of conformal invariant actions or the non-existence of extra gravitational wave modes, among other issues.

27. června 2014
!!! MIMOŘÁDNĚ V PÁTEK V 10:00 !!!
Induced fermionic current in toroidally compactified spacetimes with applications to cylindrical and toroidal nanotubes
Prof. Stefano Bellucci
Laboratori Nazionali di Frascati, INFN Roma
(seminář v angličtině)

Předchozí ročníky:


Jiří Bičák                                                                                                  Oldřich Semerák


© 24. června 2014; Oldřich Semerák <semerak@mbox.troja.mff.cuni.cz>
© 31. července 2014; vygenerováno pomocí aplikace seminar, verze 2.04 (2003-09-02); správce <Pavel.Krtous@mff.cuni.cz>