High-speed, multicolour optical photometry of the anomalous X-ray pulsar 4U 0142+61 with ULTRACAM

被引:40
作者
Dhillon, VS [1 ]
Marsh, TR
Hulleman, F
van Kerkwijk, MH
Shearer, A
Littlefair, SP
Gavriil, FP
Kaspi, VM
机构
[1] Univ Sheffield, Dept Phys & Astron, Sheffield S3 7RH, S Yorkshire, England
[2] Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England
[3] Univ Utrecht, Astron Inst, NL-3508 TA Utrecht, Netherlands
[4] Univ Toronto, Dept Astron & Astrophys, Toronto, ON M5S 3H8, Canada
[5] Natl Univ Ireland Univ Coll Galway, Dept Informat Technol, Computat Astrophys Grp, Galway, Ireland
[6] McGill Univ, Dept Phys, Montreal, PQ H3A 2T8, Canada
关键词
stars : neutron; pulsars : individual; 4U 0142+61;
D O I
10.1111/j.1365-2966.2005.09465.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present high-speed, multicolour optical photometry of the anomalous X-ray pulsar 4U 0142+61, obtained with ULTRACAM on the 4.2-m William Herschel Telescope. We detect 4U 0142+61 at magnitudes of i' = 23.7 +/- 0.1, g' = 27.2 +/- 0.2 and u' > 25.8, consistent with the magnitudes found recently by Hulleman et al. and hence confirming their discovery of both a spectral break in the optical and a lack of long-term optical variability. We also confirm the earlier discovery of Kern & Martin that 4U 0142+61 shows optical pulsations with an identical period (similar to 8.7 s) to the X-ray pulsations. The rms pulsed fraction in our data is 29 +/- 8 per cent, 5-7 times greater than the 0.2-8 keV X-ray rms pulsed fraction. The optical and X-ray pulse profiles show similar morphologies and appear to be approximately in phase with each other, the former lagging the latter by only 0.04 +/- 0.02 cycles. In conjunction with the constraints imposed by X-ray observations, the results presented here favour a magnetar interpretation for the anomalous X-ray pulsars.
引用
收藏
页码:609 / 614
页数:6
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