Issue |
A&A
Volume 444, Number 1, December II 2005
|
|
---|---|---|
Page(s) | 15 - 24 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20053472 | |
Published online | 21 November 2005 |
INTEGRAL and RXTE observations of accreting millisecond pulsar IGR J00291+5934 in outburst
1
CEA Saclay, DSM/DAPNIA/Service d'Astrophysique (CNRS FRE 2591), 91191 Gif-sur-Yvette, France e-mail: mfalanga@cea.fr
2
Unité mixte de recherche Astroparticule et Cosmologie, 11 place Berthelot, 75005 Paris, France
3
SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
4
Astronomy Division, PO Box 3000, 90014 University of Oulu, Finland
5
Laboratoire de l'Univers et de ses Théories, Observatoire de Paris, 92195 Meudon Cedex, France
6
Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
7
Dipartimento di Scienze Fisiche ed Astronomiche, Università di Palermo, via Archirafi 36, 90123 Palermo, Italy
8
School of Physics and Astronomy, University of Southampton, SO17 1BJ, UK
9
INTEGRAL Science Data Centre, 1290 Versoix, Switzerland
10
Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone, Italy
Received:
19
May
2005
Accepted:
18
August
2005
Simultaneous observations of the
accretion-powered millisecond pulsar IGR J00291+5934
by the International Gamma-Ray Astrophysics Laboratory and
Rossi X-ray Timing Explorer during the 2004 December outburst
are analysed.
The average spectrum is well described by thermal Comptonization
with an electron temperature of 50 keV and Thomson optical depth
in a slab geometry. The spectral shape is almost constant
during the outburst.
For the first time we detect a spin-up,
, of an accreting millisecond pulsar.
The ISGRI data reveal the pulsation of X-rays at a period of 1.67
milliseconds up to
keV.
The pulsed fraction is shown to increase from 6 per cent
at 6 keV to 12–20 per cent at 100 keV.
This is naturally explained by the action of the Doppler effect on the
exponentially cutoff Comptonization spectrum from the hot spot.
The nearly sinusoidal pulses show soft lags with a
complex energy dependence, increasing up to 7 keV, then decreasing to 15 keV,
and seemingly saturating at higher energies.
Key words: accretion, accretion discs / binaries: close / stars: individual: IGR J00291+5934 / stars: neutron / X-rays: binaries
© ESO, 2005
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.