Quasi-spherical subsonic accretion in X-ray pulsars

N.I. Shakura, K.A. Postnov, A.Yu. Kochetkova, L. Hjalmarsdotter
Lomonosov Moscow State University, Shternberg State Astronomical Institute, Universitetskii prosp. 13, Moscow, 119889, Russian Federation

A theoretical model is considered for quasi-spherical subsonic accretion onto slowly rotating magnetized neutron stars. In this regime the accreting matter settles down subsonically onto the rotating magnetosphere, forming an extended quasi-static shell. Angular momentum transfer in the shell occurs via large-scale convective motions resulting, for observed pulsars, in an almost iso-angular-momentum $\omega \sim 1/R^2$ rotation law inside the shell. The accretion rate through the shell is determined by the ability of the plasma to enter the magnetosphere due to Rayleigh—Taylor instabilities, with allowance for cooling. A settling accretion regime is possible for moderate accretion rates $\dot M \lesssim \dot M_* \simeq 4\times 10^{16}$ g s⁻¹. At higher accretion rates a free-fall gap above the neutron star magnetosphere appears due to rapid Compton cooling, and the accretion becomes highly non-stationary. Observations of spin-up/spin-down rates of quasi-spherically wind accreting equilibrium X-ray pulsars with known orbital periods (like, e.g., GX~301-2 and Vela~X-1) enable us to determine the main dimensionless parameters of the model as well as to estimate surface magnetic field of the neutron star. For equilibrium pulsars, the independent measurements of the neutron star magnetic field allows for an estimate of the stellar wind velocity of the optical companion without using complicated spectroscopic measurements. For non-equilibrium pulsars, a maximum value is shown to exist for the spin-down rate of the accreting neutron star. From observations of the spin-down rate and the X-ray luminosity in such pulsars (e.g., GX 1+4, SXP 1062 and 4U 2206+54), a lower limit can be put on the neutron star magnetic field, which in all cases turns out to be close to the standard value and which agrees with cyclotron line measurements. The model further explains both the spin-up/spin-down of the pulsar frequency on large time-scales and also accounts for the irregular short-term frequency fluctuations, which may correlate or anti-correlate with the observed X-ray luminosity fluctuations.

PACS: 95.30.Lz, 97.10.Gz, 97.80.Jp, 98.70.Qy (all)
DOI: 10.3367/UFNe.0183.201304a.0337
URL: https://ufn.ru/en/articles/2013/4/a/
Web of Science

000321510400001
ADS NASA

2013PhyU...56..321S
Citation: Shakura N I, Postnov K A, Kochetkova A Yu, Hjalmarsdotter L "Quasi-spherical subsonic accretion in X-ray pulsars" Phys. Usp. 56 321–346 (2013)

BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks

Received: 16th, August 2012, revised: 23rd, November 2012, accepted: 27th, November 2012

Оригинал: Шакура Н И, Постнов К А, Кочеткова А Ю, Ялмарсдоттер Л «Квазисферическая дозвуковая аккреция на рентгеновские пульсары» УФН 183 337–364 (2013); DOI: 10.3367/UFNr.0183.201304a.0337

References (77) ↓ Cited by (23) Similar articles (20)

Bildsten L et al. Astrophys. J. Suppl. 113 367 (1997)
Shakura N I, Sunyaev R A Astron. Astrophys. 24 337 (1973)
Pringle J E, Rees M J Astron. Astrophys. 21 1 (1972)
Ghosh P, Lamb F K Astrophys. J. 234 296 (1979)
Lovelace R V E, Romanova M M, Bisnovatyi-Kogan G S Mon. Not. R. Astron. Soc. 275 244 (1995)
Kluźniak W, Rappaport S Astrophys. J. 671 1990 (2007)
Fryxell B A, Taam R E Astrophys. J. 335 862 (1988)
Ruffert M Astron. Astrophys. 317 793 (1997)
Ruffert M Astron. Astrophys. 346 861 (1999)
Burnard D J, Arons J, Lea S M Astrophys. J. 266 175 (1983)
Davies R E, Pringle J E Mon. Not. R. Astron. Soc. 196 209 (1981)
Illarionov A F, Kompaneets D A Mon. Not. R. Astron. Soc. 247 219 (1990)
Bisnovatyi-Kogan G S Astron. Astrophys. 245 528 (1991)
Shakura N, Postnov K, Kochetkova A, Hjalmarsdotter L Mon. Not. R. Astron. Soc. 420 216 (2012)
Illarionov A F, Sunyaev R A Astron. Astrophys. 39 185 (1975)
Elsner R F, Lamb F K Astrophys. J. 215 897 (1977)
Arons J, Lea S M Astrophys. J. 207 914 (1976)
Bondi H Mon. Not. R. Astron. Soc. 112 195 (1952)
Arons J, Lea S M Astrophys. J. 210 792 (1976)
Kompaneets A S Zh. Eksp. Teor. Fiz. 31 876 (1956); Kompaneets A S Sov. Phys. JETP 4 730 (1957)
Weymann R Phys. Fluids 8 2112 (1965)
Shakura N, Postnov K, Hjalmarsdotter L Mon. Not. R. Astron. Soc. 428 670 (2013)
Doroshenko V, Santangelo A, Suleimanov V Astron. Astrophys. 529 52 (2011)
Finger M et al. http://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/gx1p4.html
Ikhsanov N R, Beskrovnaya N G Astron. Zhurn. 89 652 (2012); Ikhsanov N R, Beskrovnaya N G Astron. Rep. 56 589 (2012)
Lipunov V M Astrofizika Neitronnykh Zvezd (M.: Nauka, 1987); Lipunov V M Astrophysics Of Neutron Stars (Berlin: Springer-Verlag, 1992)
Chakrabarty D et al. Astrophys. J. Lett. 101 (1997)
Sunyaev R A Physics And Astrophysics Of Neutron Stars And Black Holes (Proc. of the Intern. School of Physics "Enrico Fermi", Course 65, Eds R Giacconi, R Ruffini) (Amsterdam: North-Holland Publ. Co., 1978) p. 697
Ho C et al. Mon. Not. R. Astron. Soc. 238 1447 (1989)
Nelson R W et al. Astrophys. J. 488 L117 (1997)
Hunt R Mon. Not. R. Astron. Soc. 154 141 (1971)
González-Galán A et al. Astron. Astrophys. 537 A66 (2012)
Koh D T et al. Astrophys. J. 479 933 (1997)
White N E et al. Astrophys. J. 209 L119 (1976)
Kaper L, van der Meer A, Najarro F Astron. Astrophys. 457 595 (2006)
de Kool M, Anzer U Mon. Not. R. Astron. Soc. 262 726 (1993)
Nagase F Publ. Astron. Soc. Jpn. 41 1 (1989)
Pravdo S H, Ghosh P Astrophys. J. 554 383 (2001)
La Barbera A et al. Astron. Astrophys. 438 617 (2005)
Kreykenbohm I et al. Astron. Astrophys. 427 975 (2004)
Doroshenko V et al. Astron. Astrophys. 515 A10 (2010)
Quaintrell H et al. Astron. Astrophys. 401 313 (2003)
van Kerkwijk M H et al. Astron. Astrophys. 303 483 (1995)
Rappaport S IAU Circ. 2869 2 (1975)
Bochkarev N G, Karitskaya E A, Shakura N I Pis’ma Astron. Zhurn. 1 13 (1975); Bochkarev N G, Karitskaya E A, Shakura N I Sov. Astron. Lett. 1 237 (1975)
Nagase F et al. Publ. Astron. Soc. Jpn. 38 547 (1986)
Watanabe S et al. Astrophys. J. 651 421 (2006)
Staubert R Chin. J. Astron. Astrophys. 3 (Suppl.) 270 (2003)
Doroshenko V PhD Thesis (IAAT) (Tübingen: Institut für Astronomie und Astrophysik Tübingen, Univ. Tübingen, 2011)
Davidsen A, Malina R, Bowyer S Astrophys. J. 211 866 (1977)
Hinkle K H Astrophys. J. 641 479 (2006)
Makishima K et al. Nature 333 746 (1988)
Dotani T et al. Publ. Astron. Soc. Jpn. 41 427 (1989)
Hénault-Brunet V et al. Mon. Not. R. Astron. Soc. 420 L13 (2012)
Haberl F et al. Astron. Astrophys. 537 L1 (2012)
Popov S B, Turolla R Mon. Not. R. Astron. Soc. 421 L127 (2012)
Fu L, Li X-D Astrophys. J. 757 171 (2012)
Reig P, Torrejón J M, Blay P Mon. Not. R. Astron. Soc. 425 595 (2012)
Ribó M et al. Astron. Astrophys. 449 687 (2006)
Torrejón J M et al. Astron. Astrophys. 423 301 (2004)
Masetti N et al. Astron. Astrophys. 423 311 (2004)
Blay P et al. Astron. Astrophys. 438 963 (2005)
Wang W Mon. Not. R. Astron. Soc. 398 1428 (2009)
Raymond J C, Cox D P, Smith B W Astrophys. J. 204 290 (1976)
Cowie L L, McKee C F, Ostriker J P Astrophys. J. 247 908 (1981)
Tarter C B, Tucker W H, Salpeter E E Astrophys. J. 156 943 (1969)
Hatchett S, Buff J, McCray R Astrophys. J. 206 847 (1976)
Syunyaev R A, Shakura N I Pis’ma Astron. Zhurn. 3 262 (1977); Sunyaev R A, Shakura N I Sov. Astron. Lett. 3 138 (1977)
Marykutty J et al. Mon. Not. R. Astron. Soc. 407 285 (2010)
Ducci L, Sidoli L, Paizis A Mon. Not. R. Astron. Soc. 408 1540 (2010)
Chashkina A, Popov S B New Astron. 17 594 (2012)
Landau L D, Lifshits E M Gidrodinamika (M.: Nauka, 1986); Landau L D, Lifshitz E M Fluid Mechanics (Oxford: Pergamon Press, 1987)
Wasiutyński J Studies In Hydrodynamics And Structure Of Stars And Planets (Oslo: Dybwad, 1946)
Shakura N I, Sunyaev R A Adv. Space Res. 8 135 (1988)
Shakura N I, Sunyaev R A, Zilitinkevich S S Astron. Astrophys. 62 179 (1978)
Parker E N Interplanetary Dynamical Processes (New York: Interscience Publ., 1963)
Beskin V S Osesimmetrichnye Statsionarnye Techeniya v Astrofizike (M.: Fizmatlit, 2005); Beskin V S MHD Flows In Compact Astrophysical Objects (Heidelberg: Springer, 2010)