The physics of accretion in X-ray binary pulsars - relativistic effects, pulse profiles, and emission properties
Final Report Abstract
Neutron stars can have very strong B-fields. In a binary system, matter can fall from the star onto the neutron star (“accretion”). During accretion a plasma is formed, which couples to the B-field about 1000 km from the neutron star and falls along the B-field lines with ∼30% of the speed of light onto the magnetic poles of the neutron star. On the hard surface of the neutron star an accretion column is formed, a roughly cylinder shaped object with a foot print of < 1 km2 , a height of a few km, and a luminosity of up to a few 10000 solar luminosities are created. We study the physics of the accretion column and of the interaction of the strong B-field of the neutron star with its surroundings. To study individual sources, observations of neutron stars with strong B-fields were performed with X-ray observatories and methods were developed that predict the emission of the acretion column. These include methods to model the shape of the cyclotron resonance line and methods permitting a direct comparison of theoretical models for the emission of the accretion column with observations, including relativistic light bending and models for the emission of the column at very low mass accretion rates, which agree with observations. The polarization predicted by these models agrees with observations with IXPE. The degree of polarization in these observations was larger than predicted by earlier models which ignored the effects of the quantum vacuum.
Publications
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Cyclotron resonant scattering feature simulations. Astronomy & Astrophysics, 597, A3.
Schwarm, F.-W.; Schönherr, G.; Falkner, S.; Pottschmidt, K.; Wolff, M. T.; Becker, P. A.; Sokolova-Lapa, E.; Klochkov, D.; Ferrigno, C.; Fürst, F.; Hemphill, P. B.; Marcu-Cheatham, D. M.; Dauser, T. & Wilms, J.
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Discovery and modelling of a flattening of the positive cyclotron line/luminosity relation in GX 304−1 withRXTE. Monthly Notices of the Royal Astronomical Society, 466(3), 2752-2779.
Rothschild, Richard E.; Kühnel, Matthias; Pottschmidt, Katja; Hemphill, Paul; Postnov, Konstantin; Gornostaev, Mikhail; Shakura, Nikolai; Fürst, Felix; Wilms, Jörn; Staubert, Rüdiger & Klochkov, Dmitry
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Cyclotron resonant scattering feature simulations. Astronomy & Astrophysics, 601, A99.
Schwarm, F.-W.; Ballhausen, R.; Falkner, S.; Schönherr, G.; Pottschmidt, K.; Wolff, M. T.; Becker, P. A.; Fürst, F.; Marcu-Cheatham, D. M.; Hemphill, P. B.; Sokolova-Lapa, E.; Dauser, T.; Klochkov, D.; Ferrigno, C. & Wilms, J.
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Evidence for different accretion regimes in GRO J1008−57. Astronomy & Astrophysics, 607, A88.
Kühnel, Matthias; Fürst, Felix; Pottschmidt, Katja; Kreykenbohm, Ingo; Ballhausen, Ralf; Falkner, Sebastian; Rothschild, Richard E.; Klochkov, Dmitry & Wilms, Jörn
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Luminosity-dependent changes of the cyclotron line energy and spectral hardness in Cepheus X-4. Astronomy & Astrophysics, 601, A126.
Vybornov, V.; Klochkov, D.; Gornostaev, M.; Postnov, K.; Sokolova-Lapa, E.; Staubert, R.; Pottschmidt, K. & Santangelo, A.
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Cyclotron lines in highly magnetized neutron stars. Astronomy & Astrophysics, 622, A61.
Staubert, R.; Trümper, J.; Kendziorra, E.; Klochkov, D.; Postnov, K.; Kretschmar, P.; Pottschmidt, K.; Haberl, F.; Rothschild, R. E.; Santangelo, A.; Wilms, J.; Kreykenbohm, I. & Fürst, F.
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Spectral and Timing Analysis of the Accretion-powered Pulsar 4U 1626–67 Observed with Suzaku and NuSTAR. The Astrophysical Journal, 878(2), 121.
Iwakiri, Wataru B.; Pottschmidt, Katja; Falkner, Sebastian; Hemphill, Paul B.; Fürst, Felix; Nishimura, Osamu; Schwarm, Fritz-Walter; Wolff, Michael T.; Marcu-Cheatham, Diana M.; Chakrabarty, Deepto; Tomsick, John A.; Wilson-Hodge, Colleen A.; Bissinger, Kühnel Matthias; Terada, Yukikatsu; Enoto, Teruaki & Wilms, Jörn
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Accurate Treatment of Comptonization in X-Ray Illuminated Accretion Disks. The Astrophysical Journal, 897(1), 67.
García, Javier A.; Sokolova-Lapa, Ekaterina; Dauser, Thomas; Madej, Jerzy; Różańska, Agata; Majczyna, Agnieszka; Harrison, Fiona A. & Wilms, Jörn
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Modelling of 35-d superorbital cycle of B and V light curves of IMXB HZ Her/Her X-1. Monthly Notices of the Royal Astronomical Society, 499(2), 1747-1757.
Kolesnikov, D. A.; Shakura, N. I.; Postnov, K. A.; Volkov, I. M.; Bikmaev, I. F.; Irsmambetova, T. R.; Staubert, R.; Wilms, J.; Irtuganov, E.; Golysheva, .P Yu.; Shugarov, S. Yu.; Nikolenko, I. V.; Trunkovsky, E. M.; Schönherr, G.; Schwope, A. & Klochkov, D.
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NuSTAR observation of GRO J1744–28 at low mass accretion rate. Astronomy & Astrophysics, 643, A128.
König, Ole; Fürst, Felix; Kretschmar, Peter; Ballhausen, Ralf; Sokolova-Lapa, Ekaterina; Dauser, Thomas; Sánchez-Fernández, Celia; Hemphill, Paul B.; Wolff, Michael T.; Pottschmidt, Katja & Wilms, Jörn
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The giant outburst of 4U 0115+634 in 2011 with Suzaku and RXTE. Astronomy & Astrophysics, 634, A99.
Kühnel, Matthias Bissinger né; Kreykenbohm, Ingo; Ferrigno, Carlo; Pottschmidt, Katja; Marcu-Cheatham, Diana M.; Fürst, Felix; Rothschild, Richard E.; Kretschmar, Peter; Klochkov, Dmitry; Hemphill, Paul; Hertel, Dominik; Müller, Sebastian; Sokolova-Lapa, Ekaterina; Oruru, Bosco; Grinberg, Victoria; Martínez-Núñez, Silvia; Torrejón, José M.; Becker, Peter A.; Wolff, Michael T. ... & Wilms, Jörn
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Fitting strategies of accretion column models and application to the broadband spectrum of Cen X-3. Astronomy & Astrophysics, 656, A105.
Thalhammer, Philipp; Bissinger, Matthias; Ballhausen, Ralf; Pottschmidt, Katja; Wolff, Michael T.; Stierhof, Jakob; Sokolova-Lapa, Ekaterina; Fürst, Felix; Malacaria, Christian; Gottlieb, Amy; Marcu-Cheatham, Diana M.; Becker, Peter A. & Wilms, Jörn
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X-ray emission from magnetized neutron star atmospheres at low mass-accretion rates. Astronomy & Astrophysics, 651, A12.
Sokolova-Lapa, E.; Gornostaev, M.; Wilms, J.; Ballhausen, R.; Falkner, S.; Postnov, K.; Thalhammer, P.; Fürst, F.; García, J. A.; Shakura, N.; Becker, P. A.; Wolff, M. T.; Pottschmidt, K.; Härer, L. & Malacaria, C.
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Continuum, cyclotron line, and absorption variability in the high-mass X-ray binary Vela X-1. Astronomy & Astrophysics, 660, A19.
Diez, C. M.; Grinberg, V.; Fürst, F.; Sokolova-Lapa, E.; Santangelo, A.; Wilms, J.; Pottschmidt, K.; Martínez-Núñez, S.; Malacaria, C. & Kretschmar, P.
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Vacuum polarization alters the spectra of accreting X-ray pulsars. Astronomy & Astrophysics, 674, L2.
Sokolova-Lapa, E.; Stierhof, J.; Dauser, T. & Wilms, J.
