Astronomy and Astrophysics, volume 424, 635-645 (2004/9-3)
The isolated neutron star X-ray pulsars RX J0420.0-5022 and RX J0806.4-4123: New X-ray and optical observations.
HABERL F., MOTCH C., ZAVLIN V.E., REINSCH K., GAENSICKE B.T., CROPPER M., SCHWOPE A.D., TUROLLA R. and ZANE S.
Abstract (from CDS):
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). RX J0806.4-4123
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 11.371s neutron star spin period. The X-ray spectrum is consistent with absorbed black-body emission with a temperature kT=96eV and NH
without significant changes between the two observations. Four XMM-Newton observations of RX J0420.0-5022
between December 2002 and July 2003 did not confirm the 22.7s pulsations originally indicated in ROSAT data, but clearly reveal a 3.453s period. A fit to the X-ray spectrum using an absorbed black-body model yields kT=45eV, the lowest value found from the small group of XDINs and NH
. 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 RBS1223
, RX J1605.3+3249
and RX J0720.4-3125
. For both targets we derive accurate X-ray positions from the Chandra data and present an optical counterpart candidate for RX J0420.0-5022
with B=26.6±0.3mag from VLT imaging.
X-rays: stars - stars: neutron - stars: magnetic fields - stars: individual: RX J0420.0-5022, RX J0806.4-4123
Fig.7, Table 6: [HPM99] A (No. I) added.
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