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RUBIES: JWST/NIRSpec Confirmation of an Infrared-luminous, Broad-line Little Red Dot with an Ionized Outflow

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arxiv 2403.02304 v4 pith:IEYAJCKT submitted 2024-03-04 astro-ph.GA

classification astro-ph.GA
keywords emissioncontinuumgalaxyjwstmodelalphablackbroad
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abstract

The JWST discovery of ``little red dots'' (LRDs) is reshaping our picture of the early Universe, yet the physical mechanisms driving their compact size and UV-optical colors remain elusive. Here we report an unusually bright LRD ($z=3.1$) observed as part of the RUBIES program. This LRD exhibits broad emission lines (FWHM $\sim4000$km/s), a blue UV continuum, a clear Balmer break and a red continuum sampled out to rest 4 $\mu$m with MIRI. We develop a new joint galaxy and AGN model within the Prospector Bayesian inference framework and perform spectrophotometric modeling using NIRCam, MIRI, and NIRSpec/Prism observations. Our fiducial model reveals a $M_*\sim 10^9M_\odot$ galaxy alongside a dust-reddened AGN driving the optical emission. Explaining the rest-frame optical color as a reddened AGN requires $A_{\rm v}\gtrsim3$, suggesting that a great majority of the accretion disk energy is re-radiated as dust emission. Yet despite clear AGN signatures, we find a surprising lack of hot torus emission, which implies that either the dust emission in this object must be cold, or the red continuum must instead be driven by a massive, evolved stellar population of the host galaxy -- seemingly inconsistent with the high EW broad lines (H$\alpha$ EW $\sim800$\AA). The widths and luminosities of Pa$\beta$, Pa$\delta$, Pa$\gamma$, and H$\alpha$ imply a modest black hole mass of $M_{\rm BH}\sim10^8M_\odot$. Additionally, we identify a narrow blue-shifted HeI absorption in G395M spectra, signaling an ionized outflow with kinetic energy up to $\sim1$\% the luminosity of the AGN. The low redshift of RUBIES-BLAGN-1 combined with the depth and richness of the JWST imaging and spectroscopic observations provide a unique opportunity to build a physical model for these so-far mysterious LRDs, which may prove to be a crucial phase in the early formation of massive galaxies and their supermassive black holes.

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Cited by 12 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Misaligned or chaotic? A strong break of axial symmetry in the local LRD J1025 revealed with VLT/FORS2 spectropolarimetry

    astro-ph.GA 2026-07 accept novelty 7.0 of 10

    The local Little Red Dot J1025 shows a 48° polarisation-angle offset between continuum and broad H-alpha, requiring broken axial symmetry.

  2. What you see is what you get: empirically measured bolometric luminosities of Little Red Dots

    astro-ph.GA 2025-09 conditional novelty 7.0 of 10

    Directly integrating the observed spectra of two Little Red Dots shows the bolometric luminosity is dominated by rest-frame optical light, lowering implied black hole masses to about 10^5 to 10^7 solar masses.

  3. An (in)complete NIRSpec census of Balmer absorption in Type 1 AGN -- radiation-driven outflows in little red dots, quasars and variable stars

    astro-ph.GA 2026-07 conditional novelty 6.0 of 10

    About 44% of little red dots have hydrogen-alpha absorption from outflowing gas, implying radiatively driven outflows rather than static atmospheres.

  4. Discovery of Multiply Ionized Iron Emission Powered by an Active Galactic Nucleus in a z~7 Little Red Dot

    astro-ph.GA 2025-09 conditional novelty 6.0 of 10

    The z=6.68 Little Red Dot THRILS 46403 shows a 4.5 sigma [FeVII] line, the first robust coronal-line detection among z>5 LRDs, plus narrow Balmer absorption, supporting an AGN with direct sightlines to gas at or beyon...

  5. Do Little Red Dots Vary?

    astro-ph.GA 2025-09 conditional novelty 6.0 of 10

    Super-Eddington accretion models can explain why little red dots show almost no variability, whereas standard sub-Eddington AGN variability models predict changes that should already have been seen.

  6. Investigating Little Red Dots with UV Excess: Are They the High-Redshift Siblings of Blue Hot DOGs?

    astro-ph.GA 2025-08 conditional novelty 6.0 of 10

    Little Red Dots are not the high-redshift relatives of Blue-excess Hot DOGs; they have less dust obscuration, little hot dust, and likely a different power source.

  7. Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). XXIV. 54 New Quasars and Candidate Obscured Quasars at $5.71 \le z \le 7.02$

    astro-ph.GA 2025-08 accept novelty 6.0 of 10

    Spectroscopic follow-up of the completed HSC-SSP survey yields 43 new quasars, 11 candidate obscured quasars, and 29 galaxies at z 5.71 to 7.02.

  8. MEGA: Spectrophotometric SED Fitting of Little Red Dots Detected in JWST MIRI

    astro-ph.GA 2025-08 conditional novelty 6.0 of 10

    Standard AGN and star-forming templates cannot fully reproduce the SEDs of eight MIRI-detected little red dots; dense-gas models plus extra hot dust partly work but fail on UV and narrow emission lines.

  9. Beyond the Dot: an LRD-like nucleus at the Heart of an IR-Bright Galaxy and its implications for high-redshift LRDs

    astro-ph.GA 2025-07 conditional novelty 6.0 of 10

    A z=2 LRD analog with a resolved host, plus a 99-object stacking analysis, suggests high-redshift Little Red Dots are the dimmed nuclei of extended galaxies rather than a distinct population.

  10. The BlueDOG at Cosmic Noon: A Possible Analog to Little Red Dots?

    astro-ph.GA 2025-08 conditional novelty 5.0 of 10

    A z=2.6 hyperluminous dust-obscured galaxy with an LRD-like SED hosts a ~10^10.2 Msun black hole, while the origin of its blue UV excess is left ambiguous.

  11. Little Red Dots from Small-Scale Primordial Black Hole Clustering

    astro-ph.CO 2025-07 conditional novelty 5.0 of 10

    Densely clustered 30-solar-mass primordial black holes can sequentially merge into ~10^6 solar-mass seeds by redshift 6, possibly explaining JWST little red dots, with high spin from tidal torques and a two-peak gravi...

  12. Little Red reionization factories

    astro-ph.GA 2025-08 unverdicted novelty 4.0 of 10

    LRDs may drive cosmic reionization: tidal fields are said to funnel intergalactic hydrogen into colliding streams at LRD sites, igniting starbursts that ionize the gas.

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