INTEGRAL's detection of two Galactic X-ray transient sources: SWIFT J1858.6-0814 and 4U 1901+014

M. Fiocchi*, F. Onori, A. Bazzano, A. J. Bird, V. A. Lepingwell, J. Chenevez, K. Alizai, L. Bassani, A. Malizia, N. Masetti

*Corresponding author for this work

Research output: Other contributionNet publication - Internet publicationResearch

Abstract

During a recent INTEGRAL observation as part of the Galactic Plane Scan Programme (PI: Dr. A. Bazzano), the IBIS/ISGRI instrument detected two Galactic X-ray transient sources: SWIFT J1858.6-0814 and 4U 1901+014. The sources were detected during scans performed in revolution 2081 between 2019-04-19T08:42:34 UTC and 2019-04-20T01:50:10 UTC in images made in the 22-60 keV energy range.
SWIFT J1858.6-0814 was first detected by Swift/BAT on 2018 October 31 (ATel #12151) and was detected in both soft X-rays (ATel #12158, ATel #12160, ATel #12163, ATel #12164) and hard X-rays (ATel #12167). The source remained active up to 2019 February as observed by NuSTAR (ATel #12512). SWIFT J1858.6-0814 was detected by IBIS/ISGRI in the 22-60 keV energy range with a flux of 14.5±1.9 mCrab, for an effective exposure time of 5.8 ks. From the combined JEM-X1 and JEM-X2 mosaic, we estimated a 3 sigma upper limit of 6 mCrab and 16 mCrab in the 3-10 keV and 10-25 keV energy bands, respectively, for an exposure time of 3.8 ks.
Both SWIFT/BAT and MAXI/GSC detected the fourth X-ray outburst from the binary pulsar 4U 1901+03 on 2019-02-08 (GCN #23882, ATel #12498). A NuSTAR observation which began around 2019-02-08 has shown a hard X-ray emission and a possible detection of a narrow absorption Cyclotron line around 31 keV (ATel #12684). The ISGRI/IBIS observation was performed during the decline of the source´s current outburst and 4U1901+014 was detected with a flux of 45.0±3.4 mCrab, for an effective exposure time of 1.9 ks (in the 22-60 keV energy range). This source was not within the field of view of JEM-X instruments.
All the data have been analyzed using the Offline Software Analysis version 11.0 (OSA11).
Results from the Galactic Plane Scanning are made publicly available at http://gps.iaps.inaf.it
Original languageEnglish
Publication date29 Apr 2019
Publication statusPublished - 29 Apr 2019
SeriesThe Astronomer's telegram
NumberATel #12704

Keywords

  • X-ray
  • Gamma ray
  • Binary
  • Transient

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