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INTEGRAL observations of the on-going outburst from the new X-ray transient Swift J1728.9-3613
ISDC Data Centre for Astrophysics1
Astronomisches Institut Tuebingen2
Erlangen Centre for Astroparticle Physics3
National Institute for Astrophysics4
Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark5
National Space Institute, Technical University of Denmark6
University of Geneva7
The new X-ray transient source Swift J1728.9-3613 (ATel #12436, ATel #12437, ATel #12443, ATel #12445, ATel #12455, GCN #23800) has been recently detected by INTEGRAL during the monitoring of the Galactic Center (INTEGRAL revolution 2056; PI: J. Wilms). We extracted the IBIS/ISGRI and JEM-X mosaics combining the available near real time (NRT) INTEGRAL observations (from 2019-02-12 11:55 to 2019-02-12 13:39 UTC; IBIS/ISGRI exposure time: ~5.7ks; JEM-X exposure time: ~2.7ks) and found that the source is detected at a significance of 27 σ in the 20-40 keV energy range and about 12 σ in the 40-80 keV energy range.
The corresponding fluxes are 103 ± 4 mCrab and 96 ± 8 mCrab, respectively. In the JEM-X mosaics, the source is detected at a significance of 60 σ in the 3-10 keV energy range and about 16 σ in the 10-25 keV energy range. The corresponding fluxes are 337 ± 9 mCrab and 154 ± 16 mCrab, respectively. The average preliminary JEM-X + IBIS/ISGRI spectrum (4-100 keV) can be described (χ2red=1.5, 19 dof) with an absorbed power law with photon index of 2.9 ± 0.1 and exponential rolloff at 50 (+31, -15) keV.
We fixed the absorption column density at NH=3.4E22 cm-2, according to the previous measurement in the ATel #12455. The 4-100 keV flux estimated from the spectral fit is (5.3 ± 0.8)*1E-9 erg/cm2/s (all unertainties are given at 68% confidence level). The photon index and flux are consistent with those measured by NICER about two weeks ago (ATel #12455), indicating that during this period the source did not change significantly its spectral state.
A more complete analysis will be carried on the consolidated INTEGRAL data.
Language: | English |
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Year: | 2019 |
Types: | Other |
ORCIDs: | Chenevez, J. |