Issue |
A&A
Volume 451, Number 2, May IV 2006
|
|
---|---|---|
Page(s) | 587 - 602 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20054711 | |
Published online | 02 May 2006 |
INTEGRAL survey of the Cassiopeia region in hard X rays
1
SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands e-mail: Hartog@sron.nl
2
Sterrenkundig Instituut Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
3
Sterrekundig Instituut, Universiteit Utrecht, PO Box 80000, 3508 TA Utrecht, The Netherlands
4
Max-Planck-Institut für extraterrestrische Physik, PO Box 1603, 85740 Garching, Germany
Received:
16
December
2005
Accepted:
19
January
2006
We report on the results of a deep 1.6 Ms INTEGRAL
observation of the Cassiopeia region performed from December 2003 to
February 2004. Eleven sources were detected with the imager IBIS-ISGRI
at energies above 20 keV, including three new hard X-ray sources. Most
remarkable is the discovery of hard X-ray emission from the anomalous
X-ray pulsar 4U 0142+61, which shows emission up to ~150 keV with
a very hard power-law spectrum with photon index ± 0.17. We derived flux upper limits for energies between 0.75 MeV and 30 MeV using archival data from the Compton telescope COMPTEL. In order to reconcile the very hard spectrum of 4U 0142+61 measured by
INTEGRAL with the COMPTEL upper limits, the spectrum has to bend or
break between ~75 keV and ~750 keV. 1E 2259+586,
another anomalous X-ray pulsar in this region, was not
detected. INTEGRAL and COMPTEL upper limits are provided. The new
INTEGRAL sources are IGR J00370+6122 and IGR J00234+6144. IGR J00370+6122 is a new supergiant X-ray binary with an orbital period of 15.665 ± 0.006 days, derived from RXTE
All-Sky Monitor data. Archival BeppoSAX Wide-Field Camera data yielded
four more detections. IGR J00234+6144 still requires a proper
identification. Other sources for which INTEGRAL results are presented
are high-mass X-ray binaries 2S 0114+650, γ Cas,
RX J0146.9+6121 and 4U 2206+54, intermediate polar V709 Cas and
1ES 0033+595, an AGN of the BL-Lac type. For each of these sources the
hard X-ray spectra are fitted with different models and compared with
earlier published results.
Key words: stars: neutron / stars: supergiants / stars: white dwarfs / X-rays: binaries / X-rays: general / gamma rays: observations
© ESO, 2006
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