TY - JOUR
T1 - The first broad-band X-ray study of the Supergiant Fast X-ray Transient SAX J1818.6-1703 in outburst
AU - Sidoli, L.
AU - Romano, P.
AU - Esposito, P.
AU - Parola, V. La
AU - Kennea, J. A.
AU - Krimm, H. A.
AU - Chester, M. M.
AU - Bazzano, A.
AU - Burrows, D. N.
AU - Gehrels, N.
PY - 2009/11
Y1 - 2009/11
N2 - The Supergiant Fast X-ray Transient (SFXT) SAX J1818.6-1703 underwent an outburst on 2009 May 6 and was observed with Swift. We report on these observations which, for the first time, allow us to study the broad-band spectrum from soft to hard X-rays of this source. No X-ray spectral information was available on this source before the Swift monitoring. The spectrum can be deconvolved well with models usually adopted to describe the emission from HMXB X-ray pulsars, and is characterized by a very high absorption, a flat power law (photon index ∼0.1-0.5) and a cut-off at about 7-12 keV. Alternatively, the SAX J1818.6-1703 emission can be described with a Comptonized emission from a cold and optically thick corona, with an electron temperature kTe = 5-7 keV, a hot seed photon temperature, kT0, of 1.3-1.4 keV and an optical depth for the Comptonizing plasma, τ, of about 10. The 1-100 keV luminosity at the peak of the flare is 3 × 1036 erg s -1 (assuming the optical counterpart distance of 2.5 kpc). These properties of SAX J1818.6-1703 resemble those of the prototype of the SFXT class, XTE J1739-302. The monitoring with Swift/XRT reveals an outburst duration of about 5 d, similar to other members of the class of SFXTs, confirming SAX J1818.6-1703 as a member of this class.
AB - The Supergiant Fast X-ray Transient (SFXT) SAX J1818.6-1703 underwent an outburst on 2009 May 6 and was observed with Swift. We report on these observations which, for the first time, allow us to study the broad-band spectrum from soft to hard X-rays of this source. No X-ray spectral information was available on this source before the Swift monitoring. The spectrum can be deconvolved well with models usually adopted to describe the emission from HMXB X-ray pulsars, and is characterized by a very high absorption, a flat power law (photon index ∼0.1-0.5) and a cut-off at about 7-12 keV. Alternatively, the SAX J1818.6-1703 emission can be described with a Comptonized emission from a cold and optically thick corona, with an electron temperature kTe = 5-7 keV, a hot seed photon temperature, kT0, of 1.3-1.4 keV and an optical depth for the Comptonizing plasma, τ, of about 10. The 1-100 keV luminosity at the peak of the flare is 3 × 1036 erg s -1 (assuming the optical counterpart distance of 2.5 kpc). These properties of SAX J1818.6-1703 resemble those of the prototype of the SFXT class, XTE J1739-302. The monitoring with Swift/XRT reveals an outburst duration of about 5 d, similar to other members of the class of SFXTs, confirming SAX J1818.6-1703 as a member of this class.
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U2 - 10.1111/j.1365-2966.2009.15445.x
DO - 10.1111/j.1365-2966.2009.15445.x
M3 - Article
AN - SCOPUS:70449560678
SN - 0035-8711
VL - 400
SP - 258
EP - 262
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -