Origin of spatial variation in H₂ line-to-continuum ratio in the blue lobe

Investigate the physical cause of the spatial variation in the H₂ line-to-continuum ratio within the blue-shifted lobe of DG Tau B and develop a quantitative model that explains the low ratios (0.2–0.3) near the apex and cavity walls versus higher ratios (>5) elsewhere.

Background

The NIRSpec maps reveal that the blue-shifted lobe exhibits strong continuum scattering and a broad range of H₂ line-to-continuum ratios, complicating the interpretation of in-situ emission. The authors note that some regions near the apex and cavity walls show unusually low ratios, which may indicate differences in illumination geometry or source structure, but the precise origin of these variations has not yet been established.

References

Until the origin of this spatial variation in line-to-continuum ratio is fully understood and modeled, however, only the (small) patches in the blue lobe with large ratio values > 5 can be unambiguously considered as dominated by intrinsic in-situ H$_2$ emission.

— JWST study of the DG Tau B disk wind candidate: I -- Overview and Nested H$_2$/CO outflows (2403.19400 - Delabrosse et al., 28 Mar 2024) in Section 3.1.2 (Scattered versus in-situ H₂)