THE INTEGRAL SOURCE IGR J16328-4726: A HIGH-MASS X-RAY BINARY FROM THE BEPPOSAX ERA

Journal Article · Tue Jan 01 04:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/762/1/19· OSTI ID:22167348

Fiocchi, M.; Bazzano, A.; Natalucci, L.; Persi, P.; Piro, L.; Ubertini, P. ^[1]; Bird, A. J.; Drave, S. P. ^[2]

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1. Istituto di Astrofisica e Planetologia Spaziali (INAF), Via Fosso del Cavaliere 100, Roma I-00133 (Italy)
2. School of Physics and Astronomy, University of Southampton, University Road, Southampton SO17 1BJ (United Kingdom)

We report on temporal and spectral analysis of the INTEGRAL fast transient candidate IGR J16328-4726 observed with BeppoSAX in 1998 and more recently with INTEGRAL. The MECS X-ray data show a frequent microactivity typical of the intermediate state of supergiant fast X-ray transients and a weak flare with a duration of {approx}4.6 ks. The X-ray emission in the 1.5-10 keV energy range is well described through the different time intervals by an absorbed power-law model. Comparing spectra from the lower emission level up to the peak of the flare, we note that while the power-law photon index was constant ({approx}2), the absorption column density varied by a factor of up to {approx}6-7, reaching a value of {approx}2 Multiplication-Sign 10{sup 23} cm{sup -2} at the peak of the flare. Analysis of the long-term INTEGRAL/IBIS light curve confirms and refines the proposed {approx}10.07 day period, and the derived ephemeris places the BeppoSAX observations away from periastron. Using the near- and the mid-IR available observations, we constructed a spectral infrared distribution for the counterpart of IGR J16328-4726, allowing us to identify its counterpart as a high-mass OB type star and to classify this source as a firm HMXB. Following the standard clumpy wind theory, we estimated the mass and the radius of the clump responsible for the flare. The obtained values of M {sub cl} {approx_equal} 4 Multiplication-Sign 10{sup 22}g and R{sub cl} {approx_equal} 4.4 Multiplication-Sign 10{sup 6} km are in agreement with expected values from theoretical predictions.

• OSTI ID: 22167348
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 762; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ASTRONOMY
ASTROPHYSICS
BINARY STARS
COMPARATIVE EVALUATIONS
COSMIC PHOTONS
EMISSION SPECTRA
GIANT STARS
INDEXES
INTERMEDIATE STATE
KEV RANGE
MASS
NEUTRON STARS
PHOTON EMISSION
TRANSIENTS
VISIBLE RADIATION
X RADIATION