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Center for Theoretical Physics

FacilityWarsaw, Poland
About: Center for Theoretical Physics is a(n) facility organization based out in Warsaw, Poland. It is known for research contribution in the topic(s): Gamma-ray burst & Accretion (astrophysics). The organization has 68 authors who have published 112 publication(s) receiving 1086 citation(s). The organization is also known as: Centrum Fizyki Teoretycznej PAN & Centrum Fizyki Teoretycznej Polskiej Akademii Nauk.
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Journal ArticleDOI
Abstract: We discuss two important instability mechanisms that may lead to the limit-cycleoscillations of the luminosity of the accretion disks around compact objects: ionizationinstability and radiation-pressure instability. Ionization instability is well establishedas a mechanism of X-ray novae eruptions in black hole binary systems but its ap-plicability to AGN is still problematic. Radiation pressure theory has still very weakobservational background in any of these sources. In the present paper we attempt toconfront the parameter space of these instabilities with the observational data. At thebasis of this simple survey of sources properties we argue that the radiation pressureinstability is likely to be present in several Galactic sources with the Eddington ratiosabove 0.15, and in AGN with the Eddington ratio above 0.025. Our results favor theparameterization of the viscosity through the geometrical mean of the radiation andgas pressure both in Galactic sources and AGN. More examples of the quasi-regularoutbursts in the timescales of 100 seconds in Galactic sources, and hundreds of yearsin AGN are needed to formulate firm conclusions. We also show that the disk sizes inthe X-ray novae are consistent with the ionization instability. This instability may alsoconsiderably influence the lifetime cycle and overall complexity in the supermassiveblack hole environment.Keywords: physical processes:accretion; X-rays:binaries; galaxies: active – galaxies:evolution – galaxies

70 citations

Journal ArticleDOI
Abstract: We discuss the continuum limit of the initial data for a vacuum, closed cosmological model with black holes as the only sources of the gravitational field. The model we consider is an exact solution of the constraint equations and represents a vacuum universe with a number of black holes placed on a spatial slice of S3 topology considered at the moment of its largest expansion when the black holes are momentary at rest. We explain how and under what conditions the Friedmann–Lemaitre–Robertson–Walker (FLRW) metric arises as the continuum limit when the number of black holes contained in the model goes to infinity. We also discuss the relation between the effective cosmological parameters of the model, inferred from the large scale geometry of the spacetime, and the masses of individual black holes. In particular, we prove an estimate for the difference between the total effective mass of the system and the sum of the masses of all black holes, thus quantifying the effects of the inhomogeneities in the matter distribution or the cosmological backreaction.

52 citations

Journal ArticleDOI
TL;DR: It is shown that a free quantum particle in two dimensions with zero angular momentum in the form of a ring-shaped wave packet feels an attraction towards the center of the ring, leading first to a contraction followed by an expansion.
Abstract: We show that a free quantum particle in two dimensions with zero angular momentum (s wave) in the form of a ring-shaped wave packet feels an attraction towards the center of the ring, leading first to a contraction followed by an expansion. An experiment to demonstrate this effect is also outlined.

44 citations

Journal ArticleDOI
Abstract: After a brief review of the phenomena expected in cold dense quark matter, colour superconductivity and colour-flavour locking, we sketch some implications of recent developments in our understanding of cold dense quark matter for the physics of compact stars. We give a more detailed summary of our recent work on crystalline colour superconductivity and the consequent realization that (some) pulsar glitches may originate in quark matter.

43 citations

Journal ArticleDOI
Abstract: The asymptotic structure of the gravitational field at null infinity is re‐examined by allowing certain potentials to develop ‘‘wire singularities’’, keeping the physical fields smooth. This relaxation of the regularity conditions leads to the introduction of the Newman–Unti–Tamburino (NUT) 4‐momentum which is the ‘‘magnetic’’ or the ‘‘dual’’ counterpart of the Bondi–Sachs 4‐momentum. It is shown that, unlike the Bondi–Sachs 4‐momentum, the NUT 4‐vector is absolutely conserved even in the presence of gravitational radiation. Thus, while the gravitational field resembles the nonabelian Yang–Mills fields in its ‘‘electric’’ properties, it is analogous to the abelian Maxwell field in its ‘‘magnetic’’ properties. It is pointed out that gravitational fields with nonvanishing NUT 4‐momenta may have a substantial role in quantum gravity even though they are not physically significant in classical general relativity.

43 citations


Showing all 68 results

Krishna Rajagopal5115913677
Bozena Czerny493777617
Karol Życzkowski422179165
Iwo Bialynicki-Birula411907082
Maciej Bilicki371684354
Kazimierz Rzazewski341534610
Katarzyna Małek331534224
Amer Iqbal32795338
Agnieszka Janiuk321673293
Marek Kuś311243500
Lech Mankiewicz302213533
Jerzy Kijowski281512906
Anjan A. Sen271202358
Pawel Nurowski231441951
Tomasz Sowiński191081495
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