Volume 424, Number 2, September III 2004
|Page(s)||635 - 645|
|Section||Stellar structure and evolution|
|Published online||23 August 2004|
The isolated neutron star X-ray pulsars RX J0420.0–5022 and RX J0806.4–4123: New X-ray and optical observations*
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany e-mail: email@example.com
2 Observatoire Astronomique, CNRS UMR 7550, 11 rue de l'Université, 67000 Strasbourg, France
3 Universitäts-Sternwarte, Geismarlandstr. 11, 37083 Göttingen, Germany
4 Department of Physics, University of Warwick, Coventry CV4 7AL, UK
5 Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
6 Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
7 Dipartimento di Fisica, Universitá di Padova, via Marzolo 8, 35131 Padova, Italy
Accepted: 18 May 2004
We report on the analysis of new X-ray data obtained with XMM-Newton and Chandra from two ROSAT-discovered X-ray dim isolated neutron stars (XDINs). was observed with XMM-Newton in April 2003, 2.5 years after the first observation. The EPIC-pn data confirm that this object is an X-ray pulsar with 11.371 s neutron star spin period. The X-ray spectrum is consistent with absorbed black-body emission with a temperature eV and NH = 4 cm-2 without significant changes between the two observations. Four XMM-Newton observations of between December 2002 and July 2003 did not confirm the 22.7 s pulsations originally indicated in ROSAT data, but clearly reveal a 3.453 s period. A fit to the X-ray spectrum using an absorbed black-body model yields eV, the lowest value found from the small group of XDINs and NH = 1.0 cm-2. Including a broad absorption line improves the quality of the spectral fits considerably for both objects and may indicate the presence of absorption features similar to those reported from , and . For both targets we derive accurate X-ray positions from the Chandra data and present an optical counterpart candidate for with mag from VLT imaging.
Key words: X-rays: stars / stars: neutron / stars: magnetic fields / stars: individual: ,
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.