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Astron. Astrophys. 334, 925-930 (1998)

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The two-component X-ray spectrum of the 6.4 s pulsar 1E 1048.1-5937

T. Oosterbroek 1, A.N. Parmar 1, S. Mereghetti 2 and G.L. Israel 3

1 Astrophysics Division, Space Science Department of ESA, ESTEC, P.O. Box 299, 2200 AG Noordwijk, The Netherlands
2 IFCTR, via Bassini 15, I-20133 Milano, Italy
3 Osservatorio Astronomico di Roma, via dell'Osservatorio 1, I-00040 Monteporzio Catone, Italy

Received 31 October 1997 / Accepted 6 March 1998


The 6.4 s X-ray pulsar 1E 1048.1-5937 was observed by BeppoSAX in 1997 May. This source belongs to the class of "anomalous" pulsars which have pulse periods in range 5-11 s, show no evidence of optical or radio counterparts, and exhibit long-term increases in pulse period. The phase-averaged 0.5-10 keV spectrum can be described by an absorbed power-law and blackbody model. The best-fit photon index is 2.5 [FORMULA] 0.2 and the blackbody temperature and radius are 0.64 [FORMULA] 0.01 keV and [FORMULA]  km (for a distance of 3 kpc), respectively. The detection of blackbody emission from this source strengthens the similarity with two of the more well studied "anomalous" pulsars, 1E 2259+586 and 4U 0142+614. There is no evidence for any phase dependent spectral changes.

The pulse period of [FORMULA]  s implies that 1E 1048.1-5937 continues to spin-down, but at a slower rate than obtained from the previous measurements in 1994 and 1996.

Key words: stars: neutron – pulsars: individual (1E 1048.1 – 5937) – X-rays: stars

Send offprint requests to: T. Oosterbroek: toosterb@astro.estec.esa.nl

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© European Southern Observatory (ESO) 1998

Online publication: June 2, 1998