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arXiv 1003.0418astro-ph.HE
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四毫秒钟的长期计时

Long-term timing of four millisecond pulsars

G. H. Janssen, B. W. Stappers, C. G. Bassa, I. Cognard, M. Kramer, G. Theureau

摘要:

我们使用欧洲脉冲星定时阵列网络中的多个望远镜对四个毫秒脉冲进行了定时,PSR J1721-2457,J1745-0952,J1810-2005和J1918-0642,每个脉冲长达10.5年:荷兰的韦斯特博克综合射电望远镜、法国的南凯射电望远镜和英国约德雷尔班克的洛弗尔望远镜。长的时间跨度使我们能够测量J1745-0952和J1918-0642的自行,表明它们的横向速度分别为200(50)和54(7)km/s。我们得到了J1721-2457和J1810-2005的自行上限,这意味着它们的横向速度分别小于140和400 km/s。在所有的情况下,速度都在毫秒级地震的典型范围内。我们目前的脉冲轮廓为每个脉冲星采取的观测在多个频率在350至2600 MHz的范围内,并表明,J1810-2005在这个范围内显示出显着的配置文件的演变。使用我们的多频观测,我们测量了所有四颗恒星的光谱指数,对于J1810-2005,它似乎非常平坦。J1918-0642的通量密度显示出广泛的调制,我们将其归因于折射和衍射闪烁的组合效应。我们讨论了在脉冲星计时阵列中加入J1721-2457或J1918-0642的可能性,发现在未来几年内提高脉冲星计时精度时,加入J1918-0642将是有用的。我们已经搜索了档案光学观测,以发现双星的同伴,但没有发现。然而,我们提供了PSR J 1745 -0952和J 1918 -0642的白矮星伴星的质量下限。

英文摘要:

We have timed four millisecond pulses, PSRs J1721-2457, J1745-0952, J1810-2005, and J1918-0642, for up to a total of 10.5 years each using multiple telescopes in the European Pulsar Timing Array network: the Westerbork Synthesis Radio Telescope in The Netherlands, the Nancay Radio Telescope in France and the Lovell telescope at Jodrell Bank in the UK. The long time span has enabled us to measure the proper motions of J1745-0952 and J1918-0642, indicating that they have transverse velocities of 200(50) and 54(7) km/s respectively. We have obtained upper limits on the proper motion of J1721-2457 and J1810-2005, which imply that they have transverse velocities less than 140 and 400 km/s respectively. In all cases, the velocities lie in the range typical of millisecond pulsars. We present pulse profiles for each pulsar taken from observations at multiple frequencies in the range of 350 to 2600 MHz, and show that J1810-2005 shows significant profile evolution in this range. Using our multi-frequency observations, we measured the spectral indices for all four pulsars, and for J1810-2005 it appears to be very flat. The flux density of J1918-0642 shows extensive modulation which we attribute to the combined effects of refractive and diffractive scintillation. We discuss the possible use of including J1721-2457 or J1918-0642 in a pulsar timing array, and find that J1918-0642 will be useful to include when the timing precision of this pulsar is improved over the next few years. We have searched archival optical observations to detect companions of the binary pulsars, but none were detected. However, we provide lower limits on the masses of the white dwarf companions of PSRs J1745-0952 and J1918-0642.

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