(Re)solving the complex multi-scale morphology and V-shaped SED of a newly discovered strongly-lensed Little Red Dot in Abell 383
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| Format: | Preprint |
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2025
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| _version_ | 1866914178336292864 |
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| author | Baggen, Josephine F. W. van Dokkum, Pieter Labbé, Ivo Brammer, Gabriel |
| author_facet | Baggen, Josephine F. W. van Dokkum, Pieter Labbé, Ivo Brammer, Gabriel |
| contents | We present a luminous Little Red Dot (LRD) at $z=6.027$, doubly imaged by the galaxy cluster Abell 383 and observed with JWST/NIRCam. The source shows the characteristic "V-shaped" SED and pronounced Balmer break that define the LRD population. Owing to its large magnifications, $μ\sim11$ for image S1 and $μ\sim7$ for S2, 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, we find that both dots are extremely small but resolved, with rest-frame UV sizes of $\sim 20$ pc (red) and $\sim60$ pc (blue). These compact dots are embedded in a more extended, line-dominated cloud traced most clearly in F356W ([OIII]+H$β$), which reaches scales of order $\sim$1 kpc. SED decomposition shows that the blue component has a flat UV continuum consistent with a young stellar population, whereas the red component has a steep red SED that can be interpreted as either an evolved stellar population with high stellar mass ($\log M_\star/M_\odot>10$) or a reddened AGN. If this object is representative of the LRD population, our results imply that the V-shaped SEDs of LRDs do not arise from individual compact sources but instead from the superposition of two physically distinct components. Separated by only $\sim300$ 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 gain direct insight into the physical nature of this population. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_03239 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | (Re)solving the complex multi-scale morphology and V-shaped SED of a newly discovered strongly-lensed Little Red Dot in Abell 383 Baggen, Josephine F. W. van Dokkum, Pieter Labbé, Ivo Brammer, Gabriel Astrophysics of Galaxies We present a luminous Little Red Dot (LRD) at $z=6.027$, doubly imaged by the galaxy cluster Abell 383 and observed with JWST/NIRCam. The source shows the characteristic "V-shaped" SED and pronounced Balmer break that define the LRD population. Owing to its large magnifications, $μ\sim11$ for image S1 and $μ\sim7$ for S2, 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, we find that both dots are extremely small but resolved, with rest-frame UV sizes of $\sim 20$ pc (red) and $\sim60$ pc (blue). These compact dots are embedded in a more extended, line-dominated cloud traced most clearly in F356W ([OIII]+H$β$), which reaches scales of order $\sim$1 kpc. SED decomposition shows that the blue component has a flat UV continuum consistent with a young stellar population, whereas the red component has a steep red SED that can be interpreted as either an evolved stellar population with high stellar mass ($\log M_\star/M_\odot>10$) or a reddened AGN. If this object is representative of the LRD population, our results imply that the V-shaped SEDs of LRDs do not arise from individual compact sources but instead from the superposition of two physically distinct components. Separated by only $\sim300$ 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 gain direct insight into the physical nature of this population. |
| title | (Re)solving the complex multi-scale morphology and V-shaped SED of a newly discovered strongly-lensed Little Red Dot in Abell 383 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2512.03239 |