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GRS 1915+105: The first three months with INTEGRAL

D. C. Hannikainen·O. Vilhu·J. Rodriguez·N. J. Westergaard·S. Shaw·G. G. Pooley·T. Belloni·A. A. Zdziarski·R. W. Hunstead·K. Wu·S. Brandt·A. Castro-Tirado·P. A. Charles·A. J. Dean·Ph. Durouchoux·R. P. Fender·P. Hakala·C. R. Kaiser·A. R. King·N. Lund·I. F. Mirabel·J. Poutanen
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Abstract

GRS 1915+105 is being observed as part of an Open Time monitoring program with INTEGRAL. Three out of six observations from the monitoring program are presented here, in addition to data obtained through an exchange with other observers. We also present simultaneous RXTE observations of GRS 1915+105. During INTEGRAL Revolution 48 (2003 March 6) the source was observed to be in a highly variable state, characterized by 5-minute quasi-periodic oscillations. During these oscillations, the rise is faster than the decline, and is harder. This particular type of variability has never been observed before. During subsequent INTEGRAL revolutions (2003 March-May), the source was in a steady or ''plateau'' state (also known as class $χ$ according to Belloni et al. 2000). Here we discuss both the temporal and spectral characteristics of the source during the first three months of observations. The source was clearly detected with all three gamma-ray and X-ray instruments onboard INTEGRAL.

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D. C. Hannikainen, O. Vilhu, J. Rodriguez, N. J. Westergaard, S. Shaw, G. G. Pooley, T. Belloni, A. A. Zdziarski, R. W. Hunstead, K. Wu, S. Brandt, A. Castro-Tirado, P. A. Charles, A. J. Dean, Ph. Durouchoux, R. P. Fender, P. Hakala, C. R. Kaiser, A. R. King, N. Lund, I. F. Mirabel, J. Poutanen. 2004-05-18. GRS 1915+105: The first three months with INTEGRAL. https://arxiv.org/abs/astro-ph/0405349

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