(Re)solving the Complex Multiscale Morphology and V-shaped Spectral Energy Distribution of a Newly Discovered Strongly Lensed Little Red Dot in A383

Abstract

We present a luminous "little red dot" (LRD) at $z$ = 6.027, doubly imaged by the galaxy cluster A383 and observed with the James Webb Space Telescope (JWST) NIRCam. Owing to its large magnifications, $\hat{I}¼$ $\sim$ 11 for image A383-LRD1A and $\hat{I}¼$ $\sim$ 7 for A383-LRD1B, the system is exceptionally bright and highly stretched, providing a rare, spatially resolved view of an LRD. The images reveal a complex morphology with a compact red dot, a spatially offset blue dot, and faint emission bridging and surrounding the two. After correcting for lensing, the blue and red dots have rest-frame UV and optical sizes of $\sim 60$ pc and $\lesssim 150$ pc, respectively, while extended emission traced most clearly in F356W ([O III]+H${\hat{I}}^2$) reaches scales of order $\sim 1$ kpc. Spatially resolved spectral energy distribution (SED) analysis reveals that the characteristic V-shaped SED arises from the superposition of a flat UV continuum from the blue dot, consistent with a young stellar population, and a steep red SED from the red dot, which, based on Hubble Space Telescope+JWST photometry alone, admits a straightforward stellar interpretation as a massive, heavily dust-attenuated component. However, this interpretation is challenged by Atacama Large Millimeter/submillimeter Array dust continuum upper limits, suggesting a nonstellar origin such as dense gas configurations. Separated by only $\sim$ 300 pc in the source plane, these components would blend into a single compact source in unlensed observations with the canonical LRD colors. This system therefore provides a rare opportunity to resolve the internal structure of an LRD and to begin unraveling the physical nature of this population.

Accepted for publication in ApJL

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References in corpus (3)

• Spectral Uniformity of Little Red Dots: A Natural Outcome of Coevolving Seed Black Holes and Nascent Starbursts
• Connecting the Dots: UV-Bright Companions of Little Red Dots as Lyman-Werner Sources Enabling Direct Collapse Black Hole Formation
• Little Red Dot $-$ Host Galaxy $=$ Black Hole Star: A Gas-Enshrouded Heart at the Center of Every Little Red Dot