利用南山数据对PSR B0329+54的长时标轮廓稳定性的研究

利用新疆天文台25 m射电望远镜2003—2009年对PSR B0329+54长达453 h的观测数据,研究了这颗源在1540 MHz上正常模式和反常模式的轮廓稳定性时标.通过不同时间的积分脉冲轮廓与参考轮廓交叉相关系数分析,发现随积分时间的增加,两种模式的轮廓先是以较快的速度趋于稳定,在积分时间增加到约(4±1) min时,轮廓趋稳速率放缓,当积分时间达到(140±60) min (正常模式)或达到(65±15) min (反常模式)时,轮廓趋稳速度再次变快.相关系数的结果显示两种模式的轮廓在绝大多数积分时标上都不是完全随机的涨落.如果以发生轮廓趋稳速率从快到慢转变所需的积分时间作为轮廓稳定时标的判据,两种模式的稳定时标均大约为5 min.轮廓中不同成分强度比例的涨落随积分时间的变化关系各不相同,由此可以推断3个成分强度涨落性质有差异.造成轮廓趋稳行为在不同时标上有明显差异的原因有观测噪声和星际闪烁等.

The Study for Long-time Stability of Pulse Profiles of PSR B0329+54 by Using Nanshan Data

The stability of the integrated profile of PSR B0329+54 at 1540MHz is studied with the observation data of Nanshan 25-m radio telescope up to 453 hours from 2003 to 2009. It is found that the profiles of two modes tend to stabilize at a rapid rate first, next change to a slower rate when the integration time reaches about (4±1)min, and then become rapidly stabilized again when the integration time reaches (140±60)min (normal mode) and (65±15)min (abnormal mode). The results of cross correlation coefficient show that the profile fluctuation of the two modes are not completely random. If transition time from a rapid to a lower stabilization rate is regarded as a criterion, the stability timescales of both two modes could be about 5min. The ratios between different pairs of components in the pulse profile fluctuate in different ways, suggesting that the three components in the profile follow different fluctuations. We discuss the possible reasons, such as observation noise and interstellar scintillation.