We propose to continue the INTEGRAL/multi-wavelengh monitoring of GRS 1915+105 with the goal to understand the tight connections that exist between the different emitting media, and placed in a broader context, understand accreting-ejecting sources in general. We will still take advantage of other facilities we included in the past AOs (the Sardinia and Medicina radio telescopes, Insight-HXMT in the X-rays when GRS 1915+105 is bright enough to be detected, and NICER). Based on the suggestions of AO18s TAC, and to continue with the strategy of our AO 19 program, we request 10 observations of 90 ks each taken every second revolution, in order to 1) probe the physics of accretion by studying the 3--500 keV emission of the source, 2) understand the connections between accretion and ejection processes, 3) continue monitoring GRS 1915+105 in a rare, albeit long-lasting, low luminosity state never seen before 2018. Here, providing the sources states remains unchanged, this program will allow us to accumulate more data and thus have a better view of the (rather unknown) behaviour of this source beyond 200 keV. These 3 points can almost be studied with INTEGRAL only (and our radio program for point 2). In addition INTEGRAL, with NICER and HXMT can help to study the origin of the high variability of GRS 1915+105 constrain physical models of emission processes through broad-band spectral and temporal analysis. It should be noted that GRS 1915+105 lies in a quite crowded field, with many variable sources such as X-ray binaries of all types, the enigmatic microquasar SS 433, and a couple of highly absorbed IGR sources. This survey will also permit all these sources to be studied in a regular manner. Such a monitoring will greatly participate to the INTEGRAL legacy by bringing new data for a dozen of exciting Galactic sources.
The INTEGRAL (International Gamma-Ray Astrophysics Laboratory) mission, launched by the European Space Agency (ESA) on October 17, 2002, was designed to study high-energy phenomena in the universe. INTEGRAL was operating until february 2025 and it was equipped with three high-energy instruments: the Imager on Board the INTEGRAL Satellite (IBIS), the Spectrometer on INTEGRAL (SPI), and the JEM-X (Joint European Monitor for X-rays). Its Optical Monitoring Camera (OMC) provided optical V-band magnitude measurements, complementing the high-energy observations.
European Space Agency, Rodriguez, 2025, 'GRS 1915+105 MULTI-YEAR INTEGRAL/MULTI-WAVELENGTH MONITORING PROGRAM: CLARIFYING ACCRETION-EJECTION MECHANISMS', 1.0, European Space Agency, https://doi.org/10.57780/esa-g8sr3ou
