INTEGRALPlanckGaiaHitomiPOLARCHEOPSEuclidATHENA
HEAVENSFACTCTALOFTSPICAJEM-EUSOXIPEeXTPTheseus
ISDCCDCI
Data Centre for Astrophysics
Astronomy Department of the University of Geneva

Public INTEGRAL TOO observation of V 0332+53 in outburst

ABSTRACT

We present the analysis of a 100 ks INTEGRAL (3-100 keV) observation of the transient X-ray pulsar V 0332+53 in outburst. The source is pulsating at PPulse = 4.3751±0.0002 s with a clear double pulse from 6 keV to 60 keV. The average flux was ~550 mCrab between 20 keV and 60 keV. We modeled the broad band continuum from 5 keV to 100 keV with a power-law modified by an exponential cut off. We observe three cyclotron lines: the fundamental line at 24.9±0.1 keV, the first harmonic at 50.5±0.1 keV, as well as the second harmonic at 71.7+0.7-0.8 keV, thus confirming the discovery of the harmonic lines by Coburn et al. (2005) in RXTE data.

The High-Mass X-ray Binary V 0332+53 (EXO 0331+530) underwent a dramatic outburst in January 2004 - December 2005 (see ATel 349, ATel 371, ATel 372). It was a Target of Opportunity (TOO) for an immediately public INTEGRAL observation on 6-10 January 2005, as soon as allowed by visibility constraints, first in staring mode and then in the hexagonal dithering mode for a total of about 110 ksec.

The V 0332+53 system is composed of a Be star and a pulsar with a pulsation period of 4.4 sec detected with EXOSAT by Stella et al. (1985, ApJ 288, L45). The source was first detected with Vela 5B during an outburst in 1973 (Terrell & Priedhorsky, 1984, ApJ 285, L15). A second outburst occured in 1983 and was observed with EXOSAT. A third outburst was detected by the Ginga satellite in 1989 and Quasi-Periodic Oscillations (QPOs) have been detected at a frequency of about 0.05 Hz (Takeshima et al., 1994, ApJ 436, 871).

The current outburst reaches a flux of about 1 Crab in the X-rays (3-10 keV). The V 0332+53 flux increased steadily between the end of November 2004 and New Year 2005 as can be seen on the RXTE All Sky Monitor (ASM) light curve provided by the Massachusetts Institute of Technology (MIT).

A preliminary analysis of the INTEGRAL data at the ISDC produced a high signal to noise very steep spectrum featuring 3 cyclotron lines (Soldi et al., 2005, ATel 382). This is one of the best cyclotron line spectrum ever obtained and confirms the lines discovered with RXTE by Coburn et al. (2005, ATel 381).

The observations of the Target Of Opportunity (TOO) V 0332+53 are public and available for download from our ftp site, with the data location given in the table below.

Revolutions Observation
pattern
FTP instructions
to retrieve data
Data content
272 Staring cd arc/FTP/arc_distr/TOO_272_273_274
mget *
4 tar files:
TOO_AUX_272_273_274.tar.gz (all needed auxiliary data)
TOO_SCW_272.tar.gz (science data of rev. 272)
TOO_SCW_273.tar.gz (science data of rev. 273)
TOO_SCW_274.tar.gz (science data of rev. 274)
273 Hexagonal dithering
274 Hexagonal dithering
278 Hexagonal dithering cd arc/FTP/arc_distr/TOO_278
mget *
4 tar files:
TOO_AUX_278.tar.gz (auxiliary data)
TOO_SCW_278_1.tar.gz (1st set of science data)
TOO_SCW_278_2.tar.gz (2nd set of science data)
TOO_SCW_278_REV.tar.gz (rev. data)
284 Hexagonal dithering cd arc/FTP/arc_distr/TOO_284-288
mget *284*
7 tar files:
TOO_AUX_284-288.tar.gz (auxiliary data)
TOO_SCW_284_0.tar.gz (1st set of science data)
TOO_SCW_284_1.tar.gz (2nd set of science data)
TOO_SCW_284_2.tar.gz (3rd set of science data)
TOO_SCW_284_3.tar.gz (4th set of science data)
TOO_SCW_284_4.tar.gz (5th set of science data)
TOO_SCW_284_rev.tar.gz (rev. data)
285 Hexagonal dithering cd arc/FTP/arc_distr/TOO_284-288
mget *AUX*
mget *285*
3 tar files:
TOO_AUX_284-288.tar.gz (auxiliary data)
TOO_SCW_285.tar.gz (science data)
TOO_SCW_285_rev.tar.gz (rev. data)
286 Hexagonal dithering cd arc/FTP/arc_distr/TOO_284-288
mget *AUX*
mget *286*
3 tar files:
TOO_AUX_284-288.tar.gz (auxiliary data)
TOO_SCW_286.tar.gz (science data)
TOO_SCW_286_rev.tar.gz (rev. data)
287 Hexagonal dithering cd arc/FTP/arc_distr/TOO_284-288
mget *AUX*
mget *287*
3 tar files:
TOO_AUX_284-288.tar.gz (auxiliary data)
TOO_SCW_287.tar.gz (science data)
TOO_SCW_287_rev.tar.gz (rev. data)
288 Hexagonal dithering cd arc/FTP/arc_distr/TOO_284-288
mget *AUX*
mget *288*
3 tar files:
TOO_AUX_284-288.tar.gz (auxiliary data)
TOO_SCW_288.tar.gz (science data)
TOO_SCW_288_rev.tar.gz (rev. data)