An Unusual Change in the Radio Jets of GRS 1915+105

Abstract: We compare Very Large Array observations of GRS 1915+105 made in 1994 and 2023, with nearly three decades of difference. The source has experienced intriguing major changes. The position angle of the bipolar ejecta in the plane of the sky has increased counterclockwise by 24$^\circ$. The inclination angle of the flow with respect to the line of sight has increased by 17$^\circ$. Both sets of observations show the temporal quasi-sinusoidal radio oscillations previously reported for other epochs. However, the 2023 oscillations are faster than ever before, with a period of about 8 minutes as opposed to the periods in the range of 20 to 40 minutes observed in previous epochs. Analysis of GRS 1915+105 images over the years suggest that the observed changes took place within a year or less. Our analysis indicates that during 2023 the plane of the accretion disk was aligned with the line of sight, which may explain the deep X-ray obscured state and the high mid-infrared luminosity observed with JWST in that epoch. More recent 2024 observations show that the position angle of the ejecta has returned to its historic values. Future monitoring of the time evolution of the source may clarify the cause of these remarkable changes.