English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Gravitational lens flux-ratio anomalies provide a powerful technique formeasuring dark matter substructure in distant galaxies. However, before usingthese flux-ratio anomalies to test galaxy formation models, it is imperative toascertain that the given anomalies are indeed due to the presence of darkmatter substructure and not due to some other component of the lensing galaxyhalo or to propagation effects. Here we present the case of CLASS~B1555+375,which has a strong radio-wavelength flux-ratio anomaly. Our high-resolutionnear-infrared Keck~II adaptive optics imaging and archival Hubble SpaceTelescope data reveal the lensing galaxy in this system to have a clear edge-ondisc component that crosses directly over the pair of images that exhibit theflux-ratio anomaly. We find that simple models that include the disc canreproduce the cm-wavelength flux-ratio anomaly without requiring additionaldark matter substructure. Although further studies are required, our resultssuggest the assumption that all flux-ratio anomalies are due to a population ofdark matter sub-haloes may be incorrect, and analyses that do not account forthe full complexity of the lens macro-model may overestimate the substructuremass fraction in massive lensing galaxies.

SHARP - II. Mass structure in strong lenses is not necessarily dark matter substructure: A flux ratio anomaly from an edge-on disc