This is a 2003 progress report on activities of Marek Abramowicz, a professor of astrophysics at Göteborg University, and his two Göteborg University Ph.D. students, Hans Westman and Rickard Jonsson. It will be edited by Magnus for the Onsala Space Observatory Annual 2003 Report.
For Magnus: =onsala.tex, =onsala.ps =aa.cls
TWO HIGHLIGHTS 1. EFFICIENCY OF BLACK HOLE ACCRETION R. Narayan, I.V. Igumenshchev,M.A. Abramowicz shown, using both analytic arguments and 3-D MHD supercomputer simulations, that black hole efficiency of converting mass to energy may approach 100% even for non rotating black holes, i.e. may be much larger than previously thought. They argued that the accreting gas drags in a strong poloidal magnetic field to the center such that the accumulated field disrupts the axisymmetric accretion flow at a relatively large radius. Inside the disruption radius, the gas accretes as discrete blobs or streams with a velocity much less than the free-fall velocity. Almost the entire rest mass energy of the gas is released as heat, radiation and mechanical or magnetic energy. This is a practical analog of an idealized black hole engine proposed by Geroch and Bekenstein. (Magnetically Arrested Disk: an Energetically Efficient Accretion Flow, Publications of the Astronomical Society of Japan, 2003, 55, L69)
2. QUANTUM PROBABILITIES H. Westman and A. Valentini studied the origin of the Born probability rule in the de Broglie-Bohm pilot-wave formulation of quantum theory. They argued that quantum probabilities arise dynamically, and have a status similar to thermal probabilities in ordinary statistical mechanics, and illustrated this is by numerical simulations for a two-dimensional system. They proved that a simple initial ensemble with a non-standard distribution rho not= |psi|^2 of particle positions evolves towards the quantum distribution to high accuracy. The relaxation process rho --> |psi|^2 is quantified in terms of a coarse-grained H-function (equal to minus the relative entropy of rho with respect to |psi|^2), which is found to decrease approximately exponentially over time, with a time constant that accords with a simple theoretical estimate. (gr-qc/0307040)
OTHER SIGNIFICANT RESULTS 1. RESONANCE THEORY OF THE kHz QPOs 1.1.
1.2. Paper was submitted to Astrophysical Journal Letters. 1.3. Paper will be submitted to Astrophysical Journal Letters. 1.4. This result has been obtained by W. Kluzniak, We have also performed numerical simulations of a radially perturbed accretion torus around a black hole or neutron star and find that the torus performs radial and vertical motions at the appropriate epicyclic frequencies. We find clear evidence that vertical motions are excited in a nonlinear resonance when the applied perturbation is periodic in time. The strongest resonant response occurs when the frequency difference of the two oscillations is equal to one-half the forcing frequency, precisely as recently observed in the accreting pulsar SAX J1808.4-3658, where the observed kilohertz quasi-periodic oscillation peak separation is half the spin frequency of 401 Hz. This result has been obtained by W. Lee, W. Kluzniak and 1.5. Paper is accepted by Astrophysical Journal Letters. 2. FUNDAMENTAL PHYSICS 2.1. Paper submitted to Classical and Quantum Gravity. 2.2. Paper already published in Classical and Quantum Gravity. PAPERS 1. ALREADY PUBLISHED IN REFEREED JOURNALS 01.Non-linear resonance in the accretion disk of a millisecond pulsar
W. Kluzniak, M.A. Abramowicz, S.Kato, W.H. Lee, N.Stergioulas The Astrophysical Journal Letters, 603, L89-L92, 2004
02. Resonance in Forced Oscillations of an Accretion Disk and Kilohertz Quasi-periodic Oscillations
W.H. Lee, M.A. Abramowicz, W. Kluzniak The Astrophysical Journal Letters, 603, L93-L96, 2004
03. Magnetically Arrested Disk: an Energetically Efficient Accretion Flow
R. Narayan, I.V. Igumenshchev, M.A. Abramowicz Publications of the Astronomical Society of Japan, 55, L69-L72, 2003
04. Three-dimensional Magnetohydrodynamic Simulations of Radiatively Inefficient Accretion Flows
I.V. Igumenshchev, R. Narayan, M.A. Abramowicz The Astrophysical Journal, 592, 1042-1059, 2003
05. Evidence for a 2:3 resonance in Sco X-1 kHz QPOs
M.A. Abramowicz, T. Bulik, M. Bursa, W. Kluzniak Astronomy and Astrophysics, 404, L21-L24, 2003
06. Non-Linear Resonance in Nearly Geodesic Motion in Low-Mass X-Ray
Binaries
M.A. Abramowicz, V. Karas, W. Kluzniak, W.H. Lee, P. Rebusco Publications of the Astronomical Society of Japan, 55, 467-466, 2003
07. Epicyclic Orbital Oscillations in Newton's and Einstein's Dynamics
M.A. Abramowicz, W. Kluzniak General Relativity and Gravitation, 35, 69-77, 2003
08. Book Review:
Black Hole Gravitohydromagnetics by Brian PunslyM.A. Abramowicz General Relativity and Gravitation, 35, 1131, 2003
09. Det ingen vet
M.A. Abramowicz Forskning och Framsteg, February, 2004 10. Particle detectors, geodesic motion, and the equivalence principle
S. Sonego, H. Westman Classical and Quantum Gravity, 21, 433-444, 2004
2. ALREADY PUBLISHED CONFERENCE PROCEEDINGS 11.Interpreting black hole QPOs
Invited lecture at X-Ray Timing 2003: Rossi and Beyond (Harvard, 2003)
M.A. Abramowicz, W.Kluzniak X-Ray Timing 2003: Rossi and Beyond, ed. P. Kaaret, F. K. Lamb, & J. H. Swank (Melville, NY: American Institute of Physics) 12. High-frequency QPOs as a problem in physics: non-linear resonance
Presented at X-Ray Timing 2003: Rossi and Beyond (Harvard, 2003)
W.Kluzniak, M.A. Abramowicz, W.H. Lee In print: "X-Ray Timing 2003: Rossi and Beyond", ed. P. Kaaret, F. K. Lamb, & J. H. Swank (Melville, NY: American Institute of Physics) 3. IN PRINT AND SUBMITTED 01.The orbital resonance model for twin peak kHz QPOs
M.A. Abramowicz, W.Kluzniak, Z.Stuchlik, G.Torok Submitted: Astronomy and Astrophysics astro-ph/0401464 02. The importance of discovering a 3:2 twin-peak QPO in a ULX or how to solve the puzzle of intermediate mass black holes
M.A. Abramowicz, W.Kluzniak, J.E. McClintock, R.A. Remillard Accepted: The Astrophysical Journal Letters astro-ph/0402012 03. Twin peaks kHz QPOs: mathematics of the 3:2 orbital resonance
P. Rebusco In print: Publications of the Astronomical Society of Japan astro-ph/0403341 04. The Hartle-Thorne circular geodesics
M.A. Abramowicz, G.J.E. Almergren, W. Kluzniak, A.V. Thampan Submitted: Classical and Quantum Gravity gr-qc/0312070 05. Of NBOs and kHz QPOs: a low-frequency modulation
in resonant oscillations of relativistic accretion disks
J.Horak, M.A. Abramowicz, V.Karas, W. Kluzniak Submitted: The Astrophysical Journal Letters SUPERVISION OF DIPLOMA WORKS 1. DIPLOMA WORKS FINISHED IN 2003 01.Rotation in strong gravity
Joachim Almergren, degree obtained: Ph.D. Sissa, Trieste I supervised 1/2 of this work 02. Risonanza parametrica di dinamiche quasi geodetiche
con campi gravitationali forti Paola Rebusco, degree obtained: Laurea in Physics Department of Physics, University of Trieste I was an official co-supervisor of this work 2. DIPLOMA WORKS SUPERVISED IN 2003 01.Pilot wave theory
Hans Westman, degree to be obtained: Ph.D. Göteborg University Will be finished in 2004 02. Inertial forces in Einstein's general relativity
Rickard Jonsson, degree to be obtained: Ph.D. Göteborg University Will be finished in 2005 03. QPOs resonance theory
Gabriel Török, degree to be obtained: Ph.D. Silesian University in Opava, and Chalmers (Erasmus/Socrates) Will be finished in 2006 LECTURES AT SUMMER SCHOOLS 1. International School on "Black Holes in the Universe" Cargèse, Corsica (France) May 12-24, 2003 The study of black holes is currently seeing a large increase of interest in modern astrophysics. The purpose of the school "Black Holes in the Universe" is, at this timely stage, to review the current knowledge and the outstanding questions in black hole astrophysics, both observationally and theoretically. The school will mainly comprise detailed lectures given by leading experts in the field. They will be complemented by sessions of questions and answers and seminars. The school is aimed at PhD students, postdocs, and young researchers in the field in priority, and to all researchers with an interest for the school topics within the space allocation. A total number of 50 participants will be accommodated. I had an 8 hour series of lectures "Accretion around black holes", and was a member of the School scientific committee (other members: Eric Gourgoulhon, Jean-Marie Hameury, Jacques Paul, Rachid Sunyaev). I invited Paola Rebusco to participate as a student at the School, and this gave us an ample time to work on the QPOs resonance theory. 2. Nordita Master Class in Physics, Den Nordiske Lejrskole, Hillerød (Denmark)
3-10 August, 2003 Nordita organized a one-week school of physics in Hillerød (a picturesque suburb North of Copenhagen) for best students from the Nordic and Baltic countries and NW Russia region. The school aims at introducing frontier areas of physics research by world top scientists at a level understandable for undergraduate students, and also to stimulate further studies. It gives a unique possibility for students to meet outstanding scientists both in class and in informal atmosphere. The lectures will be accompanied by excercises in groups and discussion sessions. I had a 5 hour series of lectures "Theory of accretion disks around black holes" INVITED LECTURES AT CONFERENCES 1. Tenth Marcel Grossmann Meeting on General Relativity 2. The 25th Aniversary of the Copernicus Centre 3. 5th RagTime Workshop, Silesian University
4. X-Ray Timing 2003: Rossi and Beyond SCIENTIFIC VISITS ABROAD 1. Institut d'Astrophysique, Paris (France) 2. Silesian University, Opava (Czech Republic) 3. Copernicus Centre, Warsaw (Poland) 4. The UKAFF Supercomputer Centre, Leicester (England) 5. Short visits |