BEPPOSAX and Chandra Observations of SAX J0103.2-7209 = 2E 0101.5-7225: A New Persistent 345 Second X-Ray Pulsar in the Small Magellanic Cloud
Abstract
We report the results of a 1998 July BeppoSAX observation of a field in the Small Magellanic Cloud which led to the discovery of ~345 s pulsations in the X-ray flux of SAX J0103.2-7209. The BeppoSAX X-ray spectrum is well fitted by an absorbed power law with a photon index of ~1.0 plus a blackbody component with kT=0.11 keV. The unabsorbed luminosity in the 2-10 keV energy range is ~1.2x1036 ergs s-1. In a very recent Chandra observation, the 345 s pulsations are also detected. The available period measurements provide a constant period derivative of -1.7 s yr-1 over the last 3 years, making SAX J0103.2-7209 one of the most rapidly spinning up X-ray pulsars known. The BeppoSAX position (30" uncertainty radius) is consistent with that of the Einstein source 2E 0101.5-7225 and the ROSAT source RX J0103.2-7209. This source was detected at a luminosity level of a few times 1035-1036 ergs s-1 in all data sets of past X-ray missions since 1979. The ROSAT HRI and Chandra positions are consistent with that of a mV=14.8 Be spectral-type star already proposed as the likely optical counterpart of 2E 0101.5-7225. We briefly report and discuss photometric and spectroscopic data carried out at the ESO telescopes 2 days before the BeppoSAX observation. We conclude that SAX J0103.2-7209 and 2E 0101.5-7225 are the same source: a relatively young and persistent X-ray pulsar in the SMC. The results reported in this Letter are partially based on observations carried out at ESO, La Silla, Chile (61.D-0513).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2000
- DOI:
- 10.1086/312546
- arXiv:
- arXiv:astro-ph/0001423
- Bibcode:
- 2000ApJ...531L.131I
- Keywords:
-
- STARS: BINARIES: GENERAL;
- STARS: PULSARS: INDIVIDUAL: ALPHANUMERIC: SAX J0103.2-7209;
- STARS: PULSARS: INDIVIDUAL: ALPHANUMERIC: 2E 0101.5-7225;
- STARS: EMISSION-LINE;
- BE;
- STARS: ROTATION;
- X-RAYS: STARS;
- Astrophysics
- E-Print:
- 4 pages. Accepted for publication in ApJ Letters. Emulateapj style used