Hunting ghosts: the iconic stellar stream(s) around NG5907 under scrutiny

TL;DR

This study re-examines the iconic stellar stream around NGC5907 using deep imaging, finding only a single stream and questioning the existence of the previously claimed double loop, highlighting the importance of independent verification.

Contribution

The paper provides new deep imaging data that challenges prior claims of a double loop stellar stream around NGC5907, emphasizing the necessity for independent confirmation of faint features.

Findings

Only a single, knee-shaped stellar stream was observed.

The previously claimed double loop was not confirmed.

Independent observations are crucial for verifying low-surface brightness features.

Abstract

Stellar streams are regarded as crucial objects to test galaxy formation models, with their morphology tracing the underlying potentials and their occurrence tracking the assembly history of the galaxies. The existence of one of the most iconic stellar streams, the double loop around NGC5907, has recently been questioned by new observations with the Dragonfly telescope. This new work only finds parts of the stream, even though they reach a 1 sigma surface brightness limit of 30.3 mag per sq. arcsec in the g-band. Using 7.2 hours of Luminance L-band imaging with the Milankovi\'c 1.4 meter telescope, we have re-observed the putative double loop part to confirm or reject this assessment. We do not find signs of the double loop, but see only a single, knee-shaped stellar stream. Comparing our to the data by the Dragonfly team, we find the same features. Our observations reach a 1 sigma surface brightness limit of 29.7 mag per sq. arcsec in the g-band. These findings emphasize the need for independent confirmation of detections of very low-surface brightness features.