Spatial decomposition of Little Red Dots with JWST/NIRSpec IFU into broad-line red cores and narrow-line blue host galaxies
Yuzo Ishikawa, Anna-Christina Eilers, Rohan P. Naidu, Jorryt Matthee, Rongmon Bordoloi, John Chisholm, Jenny E. Greene, Yilun Ma, Pascal A. Oesch, Wendy Q. Sun, Alberto Torralba, John R. Weaver, Stijn Wuyts, Mengyuan Xiao
astro-ph.GA
Submitted: 2026-07-10
Comments: 16 pages, 11 figures, submitted
Code: https://github.com/spacetelescope/jwst
License: http://creativecommons.org/licenses/by/4.0/
The gist: Little Red Dots (LRDs) are a population of compact red sources discovered by the James Webb Space Telescope (JWST).
Terminology
Abstract
Little Red Dots (LRDs) are a population of compact red sources discovered by the James Webb Space Telescope (JWST). Imaging and spectroscopy have shown that LRDs exhibit a complex spectrum with a ``V-shaped" continuum, broad Balmer emission lines, and in some cases Balmer absorption. While the physical origin of these components remains debated, recent studies propose that they arise from a compact central engine likely hosting a rapidly growing black hole embedded within a more extended host galaxy. We test this central engine + host galaxy model using JWST/NIRSpec integral field unit (IFU) spectroscopy to spectrally decompose the observed continuum, narrow and broad emission lines, and absorption. We spatially map each component for five broad Ha-selected LRDs at z 5 observed with both the prism and high-resolution G395H grating. We find that the blue continuum emission is co-spatial with the narrow emission line region, while the red continuum arises from a compact core co-spatial with the broad Balmer emission and absorption. Spatial maps of the [OIII] equivalent width reveal a pronounced decrease in the central core. Our work provides further evidence that the LRD emission is produced by at least two distinct physical components arising from a red central engine embedded within a blue host galaxy.
Sources
- (Re)solving the Complex Multiscale Morphology and V-shaped Spectral Energy Distribution of a Newly Discovered Strongly Lensed Little Red Dot in A383
- Too Quiet for Comfort: Local Little Red Dots Lack Variability over Decades
- A PANORAMIC of UV-optical morphologies of "Little Red Dots": Two groups of LRDs distinguished by UV half-light radius
- Little Red Dots host Black Hole Stars: A unified family of gas-reddened AGN revealed by JWST/NIRSpec spectroscopy
- The case for super-Eddington accretion in JWST broad-line AGN during the first billion years
- The GlimmIr: Spectroscopic Variability in a z~7 LRD Indicates Rapid Changes in Both the Narrow and Broad Line Regions
- (LRDs)$^2$: The Low-ReDshift Little Red Dots Survey. II. DESI DR1 Sample
- How I Wonder What You Are -- JWST's Little Red Dots do not TWINKLE
- No Luminous Little Red Dots: A Sharp Cutoff in Their Luminosity Function
- Non-LTE atmosphere models of very luminous sources and their applicability to Little Red Dots, quasi-stars, and similar objects
- The Engine and its Flows: Little Red Dot spectra are shaped by the column densities of their gas envelopes
- A "Black Hole Star" Reveals the Remarkable Gas-Enshrouded Hearts of the Little Red Dots
- Little Red Dots as Intermediate Mass, Super-Eddington Engines: Insights from Type IIn Supernovae and The 1837-1856 Great Eruption of eta Carinae
- A new sample of Little Red Dots at $z<0.45$ in DESI DR1: Broad Balmer lines, low ionization spectrum and no variability
- Beyond the Dot: an LRD-like nucleus at the Heart of an IR-Bright Galaxy and its implications for high-redshift LRDs
- Little Red Dot $-$ Host Galaxy $=$ Black Hole Star: A Gas-Enshrouded Heart at the Center of Every Little Red Dot
- VENUS: Two Faint Little Red Dots Separated by $\sim70\,\mathrm{pc}$ Hidden in a Single Lensed Galaxy at $z\sim7$
- Extended Components of Little Red Dots in the Rest-Frame Optical
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