Milliarcsecond-scale jet reorientations in GRS 1915+105 pointing towards a warped accretion disc

The black hole X-ray binary GRS 1915+105 was persistently X-ray bright for over 26 years before entering a prolonged low X-ray flux state in 2018, while remaining bright at radio wavelengths. The new analysis still awaits peer review, but it already lays out the central claim clearly.

That matters because astrophysics becomes persuasive only when an observed signal can be tied to a physically defensible explanation. Compact objects such as neutron stars and black holes are natural laboratories for extreme physics, but the distance and complexity of these systems make interpretation difficult without multi-wavelength coverage and careful modeling. A detection without a mechanism is only half a result. the other half comes from showing that the signal fits quantitatively inside a coherent physical picture rather than merely being consistent with a broad family of models. Multi-wavelength observations suggest this state results from a complex layer of absorbing material of unknown nature. Radio jet observations provide an unobstructed view of the physical changes during this phase, and recent Very Large Array and East Asian VLBI Network observations revealed.

We use higher-resolution VLBI observations to investigate the connection between the obscuration event and the jet behaviour close to the launch region. We observed GRS 1915+105 with the Very Long Baseline Array and European VLBI Network at four epochs during the early obscuration phase (2019-2021), sampling a diverse range of jet.

We study the milliarcsecond jet morphology and PA changes and relate these to the reported X-ray behaviour. Many post-2018 PAs are significantly offset from the pre-obscuration jet axis, which has a weighted mean of $142^\circ \pm 7^\circ$ on milliarcsecond scales.

We measure a maximum offset of $57^\circ \pm 8^\circ$, the largest reported for GRS 1915+105 to date. Our epochs reveal a variety of jet behaviour, ranging from a stable, compact source with a large PA offset, to a bright, flaring source with a similar offset, to an extended jet.

The broader interest lies in turning an observational clue into something that can be weighed against competing models of the underlying physics. Astrophysics does not have the luxury of controlled experiments; everything is inferred from radiation that traveled across cosmic distances under conditions that cannot be reproduced in a terrestrial laboratory. This makes the interpretation chain longer and more uncertain than in bench science, but it also means that a well-constrained measurement of an extreme object carries theoretical information that no earthbound experiment can provide.

The lack of measurable PA changes within individual 8-hour epochs rules out rapid Lense-Thirring precession of the inner disc as the direct driver of the jet reorientation. Instead, the timescales involved, the system geometry, and the apparent connection to the X-ray obscuration favour a radiation-driven warped accretion disc, a configuration that.

Because this is still a preprint, the result should be read with genuine interest and proportionate caution. Peer review is not a guarantee of correctness, but it is a process that forces authors to respond to technical criticism from specialists who have no stake in a particular outcome. Preprints that survive that process, often with substantive revisions, emerge with a stronger evidential base than the version that first appeared. Until that stage is complete, the responsible reading keeps uncertainty explicitly visible rather than treating the claims as established findings.

The next step is to see whether independent datasets and physical modeling converge on the same interpretation. Multi-wavelength follow-up, combining X-ray, radio and optical data where possible, is typically what separates a compelling detection from a robust physical characterization. In high-energy astrophysics, results that initially looked definitive have been revised when data from a second messenger arrived; the current result should be read with that history in mind. Until peer review and independent follow-up address those open questions, skepticism is not a failure of appreciation for the work; it is part of how science decides what to keep.

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