INTEGRAL and RXTE monitoring of XTE J1817-330: evolving through a state change?

E. Kuulkers*, P. Goldoni, S. E. Shaw, S. Brandt, J. Chenevez, T. J.-L. Courvoisier, K. Ebisawa, P. Kretschmar, C. Markwardt, N. Mowlavi, T. Oosterbroek, A. Orr, A. Paizis, J. Rodriguez, C. Sanchez-Fernandez, R. Wijnands

*Corresponding author for this work

Research output: Other contributionNet publication - Internet publicationResearch

Abstract

INTEGRAL Galactic Bulge monitoring observations (ATel #438) indicate that the X-ray transient and black-hole candidate XTE J1817-330 (ATel #714) has increased in hard X-rays (20-60 keV) compared to the observations performed on Feb 9, 2006 (ATel #731). The 20-60 keV fluxes were 46+/-2 mCrab on Feb 11 and 79+/-2 mCrab on Feb 14. The 60-150 keV fluxes did not show a significant increase: they were 45+/-7 and 60+/-7 mCrab, respectively, on the above quoted days. Preliminary spectral analysis indicates that in the range 20-150 keV the spectrum of the source has indeed steepened: a power-law with photon index of 2.6+/-0.1 fits the INTEGRAL observations on Feb 14.

The RXTE/PCA Galactic Bulge scans, however, show a decrease of the source at lower energies (2-10 keV), from 840 mCrab on Feb 9 to 710 mCrab on Feb 12 to 670 mCrab on Feb 15 (all +/-4 mCrab). This is in contrast to the spectral behaviour described above.

These findings may indicate a state change, which could be accompanied by changes in the emission at other wavelengths. We again note that an INTEGRAL ToO observation of XTEJ1817-330 is presently ongoing and will last up to Feb 17, 11:20 UTC. Observations at other wavelengths are therefore encouraged.
Original languageEnglish
Publication date16 Feb 2006
Publication statusPublished - 16 Feb 2006
SeriesThe Astronomer's telegram
NumberATel #738

Keywords

  • X.ray
  • Gamma ray
  • Binary
  • Black hole
  • Transient
  • Variables

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