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          Institute: MPI für extraterrestrische Physik     Collection: High Energy Astrophysics at MPE     Display Documents

ID: 5658.0, MPI für extraterrestrische Physik / High Energy Astrophysics at MPE
The thermal radiation of the isolated neutron star RX J1856.5- 3754 observed with Chandra and XMM-Newton
Authors:Burwitz, V.; Haberl, F.; Neuhäuser, R.; Predehl, P.; Trümper, J.; Zavlin, V. E.
Date of Publication (YYYY-MM-DD):2003-03
Title of Journal:Astronomy & Astrophysics
Journal Abbrev.:Astron. Astrophys.
Issue / Number:3
Start Page:1109
End Page:1114
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We present results of the analysis of data collected in 57-ks XMM-Newton and 505-ks Chandra observations of the nearby (similar or equal to120pc) isolated neutron star RXJ1856.5- 3754. We confirm most of the statements made by Burwitz et al. (2001) who discussed the original 55-ks Chandra data. Detailed spectral analysis of the combined X-ray and optical data rules out the currently available nonmagnetic light and heavy element neutron star atmosphere (LTE) models with hydrogen, helium, iron and solar compositions. We find that strongly magnetized atmosphere models also are unable to represent the data. The X- ray and optical data show no spectral features and are best fitted with a two-component blackbody model with kT(bb,X)(infinity) similar or equal to 63.5 eV and R- bb,X(infinity) similar or equal to 4.4 (d/120 pc) km for the hot X-ray emitting region, and kT(bb,opt)(infinity) < 33 eV and R-bb,opt(infinity) > 17 (d/20 pc) km for the rest of the neutron star surface responsible for the optical flux. The large number of counts collected with XMM-Newton allows us to reduce the upper limit on periodic variation in the X-ray range down to 1.3% (at a 2sigma confidence level) in the 10(-3)-50 Hz frequency range. In an attempt to explain this small variability, we discuss an one-component model with kT(bb)(infinity) similar or equal to 63 eV and R-bb(infinity) similar or equal to 12.3 (d/120 pc) km. This model requires a low radiative efficiency in the X-ray domain, which may be expected if the neutron star has a condensed matter surface.
Free Keywords:stars : atmospheres; stars : individual : RX J1856.5-3754; stars : neutron; X-rays : stars
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für extraterrestrische Physik
External Affiliations:Max Planck Inst Extraterr Phys, POB 1312, D-85741 Garching,; Germany; Max Planck Inst Extraterr Phys, D-85741 Garching, Germany
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