The Angular Momentum of Accreting Neutron Stars：（合生中子星的角动量）.pdfVIP

The Angular Momentum of Accreting Neutron Stars Lars Bildsten 8 Department of Physics and Department of Astronomy 9 9 University of California, Berkeley, CA 94720 1 n a J Abstract. I review the rotation measurements of accreting neutron stars. Many 7 of the highly magnetic (B 1011 G) accreting X-ray pulsars have been con- tinuously observed with the Burst and Transient Source Experiment (BATSE) 1 v aboard the Compton Gamma-Ray Observatory (CGRO) since April 1991. These 3 observations show that the accretion torque exerted on many disk-fed accret- 4 ing X-ray pulsars changes sign on a monthly to yearly timescale. This results 0 in alternating periods of spin-up and spin-down with nearly the same torques, 1 0 leading to little net angular momentum gained by accretion. I also summarize 8 recent discoveries with the Rossi X-Ray Timing Explorer (RXTE) of periodicities 9 during Type I X-ray bursts. These seem to indicate that many of the rapidly / −10 −1 11 ˙ h accreting (M 10 M⊙ yr ) and weakly magnetic (B ≪ 10 G) neutron stars in our galaxy are rotating at frequencies 250 Hz. Most remarkable is p ∼ - that they all rotate within a rather narrow range of frequencies. o r t s a : I INTRODUCTION v i X Since the discovery of neutron stars (NSs) over 30 ye