UNCOVER: 404 Error -- Models Not Found for the Triply Imaged Little Red Dot A2744-QSO1

Abstract

JWST has revealed an abundance of compact, red objects at $z\approx 5-8$ dubbed "little red dots" (LRDs), whose SEDs display a faint blue UV continuum followed by a steep rise in the optical. Despite extensive study of their characteristic V-shaped SEDs, the nature of LRDs remains unknown. We present a new analysis of the NIRSpec/PRISM spectrum of A2744-QSO1, a triply imaged LRD at $z=7.04$ from the UNCOVER survey. The spectrum shows a strong Balmer break and broad Balmer emission lines, both of which are difficult to explain with models invoking exclusively AGN or stellar contributions. Our fiducial model decomposes the spectrum into a post-starburst galaxy dominating the UV-optical continuum and a reddened AGN being sub-dominant at all wavelength and contributing at $\sim 20\%$ level. However, our most credible model infers a stellar mass of $M_{\star }\approx 4\times 10^9{\mathrm{M}}_{\odot }$ within a radius of $r_{\mathrm{e}}<30$pc, driving its central density to the highest among observations to date. This high central density could be explained if A2744-QSO-1 is the early-forming core of a modern-day massive elliptical galaxy that later puffed up via the inside-out growth channel. The models also necessitate an unusually steep dust law to preserve the strong break strength, though this steepness may be explained by a deficit of large dust grains. It is also probable that these challenges reflect our ignorance of A2744-QSO1's true nature. Future variability and reverberation mapping studies could help disentangle the galaxy and AGN contribution to the continuum, and deeper redder observations could also unveil the dust properties in LRDs.

Accepted by ApJ

References in corpus (35)

• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope I. Overview of the instrument and its capabilities
• A Comprehensive Study on Galaxies at z~9-16 Found in the Early JWST Data: UV Luminosity Functions and Cosmic Star-Formation History at the Pre-Reionization Epoch
• The James Webb Space Telescope Mission
• A CEERS Discovery of an Accreting Supermassive Black Hole 570 Myr after the Big Bang: Identifying a Progenitor of Massive z > 6 Quasars
• JADES. The diverse population of infant Black Holes at 4<z<11: merging, tiny, poor, but mighty
• Formation of the first nuclear clusters and massive black holes at high redshift
• Efficient Formation of Massive Galaxies at Cosmic Dawn by Feedback-Free Starbursts
• Hubble Space Telescope Combined Strong and Weak Lensing Analysis of the CLASH Sample: Mass and Magnification Models and Systematic Uncertainties
• A massive quiescent galaxy at redshift 4.658
• JWST CEERS & JADES Active Galaxies at z = 4-7 Violate the Local $M_{\bullet }-M_{\star }$ Relation at $>3\sigma$: Implications for Low-Mass Black Holes and Seeding Models
• Rapid growth of seed black holes in the early universe by supra-exponential accretion
• Type II Quasars from the Sloan Digital Sky Survey: V. Imaging host galaxies with the Hubble Space Telescope
• JWST/NIRCam Probes Young Star Clusters in the Reionization Era Sunrise Arc
• RUBIES: Evolved Stellar Populations with Extended Formation Histories at $z\sim 7-8$ in Candidate Massive Galaxies Identified with JWST/NIRSpec
• A Near-Infrared Spectroscopic Survey of K-selected Galaxies at z~2.3: Redshifts and Implications for Broadband Photometric Studies
• JWST UNCOVER: Extremely red and compact object at$z_{\mathrm{phot}}\simeq 7.6$ triply imaged by Abell 2744
• UNCOVERing the extended strong lensing structures of Abell 2744 with the deepest JWST imaging
• Heavily reddened type 1 quasars at z > 2 I: Evidence for significant obscured black-hole growth at the highest quasar luminosities
• A dusty compact object bridging galaxies and quasars at cosmic dawn
• Deciphering the JWST spectrum of a 'little red dot' at $z\sim 4.53$: An obscured AGN and its star-forming host
• Mildly Super-Eddington Accretion Onto Slowly-Spinning Black Holes Explains the X-Ray Weakness of the Little Red Dots
• JADES -- The Rosetta Stone of JWST-discovered AGN: deciphering the intriguing nature of early AGN
• Modelling type 1 quasar colours in the era of Rubin and Euclid
• The contribution from stars stripped in binaries to cosmic reionization of hydrogen and helium
• Little Red Dots: Rapidly Growing Black Holes Reddened by Extended Dusty Flows
• Size matters: are we witnessing super-Eddington accretion in high-redshift black holes from JWST?
• A physically-based model of the ionizing radiation from active galaxies for photoionization modeling
• Compact massive objects in Virgo galaxies: the black hole population
• Formation of supermassive stars in the first star clusters
• Dust attenuation evolution in $z\sim 2$-$12$ JWST galaxies
• Observable and ionizing properties of star-forming galaxies with very massive stars and different IMFs
• Exploring a primordial solution for early black holes detected with the JWST
• Galaxies with grains: unraveling dust evolution and extinction curves with hydrodynamical simulations

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• Investigating photometric and spectroscopic variability in the multiply-imaged Little Red Dot A2744-QSO1
• A direct black hole mass measurement in a Little Red Dot at the Epoch of Reionization
• Dust Budget Crisis in Little Red Dots
• The warm outer layer of a Little Red Dot as the source of [Fe II] and collisional Balmer lines with scattering wings
• SHELLQs. Bridging the Gap: JWST Unveils Obscured Quasars in the Most Luminous Galaxies at z > 6
• Spectral Uniformity of Little Red Dots: A Natural Outcome of Coevolving Seed Black Holes and Nascent Starbursts
• Possible environmental quenching in an interacting little red dot pair at $z\sim 7$
• A weak Ly$\alpha$ halo for an extremely bright Little Red Dot: Indications of enshrouded SMBH growth
• pop-cosmos: Insights from generative modeling of a deep, infrared-selected galaxy population
• On the ages of the stellar populations of galaxies at $z=0.1$-7
• The implications of overmassive black holes at $z>5$ for quasar and black hole growth
• Signatures of Exploding Supermassive PopIII Stars at High Redshift in JWST, EUCLID and Roman Space Telescope
• Discovery of low-redshift analogues to "Little Red Dots" in DESI: A later evolutionary stage of compact LRDs?
• Rapid sinking and efficient mergers of supermassive black holes in compact high-redshift galaxies
• AGILE: an end-to-end Rubin-LSST simulation of AGNs, galaxies, and stars I. Software description and first data release