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The Vera C. Rubin Observatory LSST is expected to discover tens of millions of new Active Galactic Nuclei (AGNs). The survey's exceptional cadence and sensitivity will enable UV/optical/NIR monitoring of a significant fraction of these…

The recent observations of highly accreting supermassive black holes (SMBH) at very high redshift ($>$4) with the James Webb Space Telescope (JWST) allowed us to shed light for the very first time on the early evolutionary phases of active…

Astrophysics of Galaxies · Physics 2025-09-05 M. Berton , E. Järvelä , A. Tortosa , C. Mazzucchelli

Observations with the James Webb Space Telescope (JWST) have uncovered numerous faint active galactic nuclei (AGN) at $z\sim5$ and beyond. These objects are key to our understanding of the formation of supermassive black holes (SMBHs),…

Recent observations have revealed a unique class of active galactic nuclei (AGNs), termed little red dots (LRDs). These objects are hypothesized to be powered by massive black holes rapidly accreting in dense gaseous environments.…

Astrophysics of Galaxies · Physics 2026-05-22 Shinsuke Takasao , Kohei Inayoshi

The James Webb Space Telescope (JWST) has uncovered a population of compact, high-redshift sources, the Little Red Dots (LRDs), which may host supermassive black holes (BHs) significantly heavier than their stellar content compared with…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-23 Valerio De Luca , Loris Del Grosso , Gabriele Franciolini , Konstantinos Kritos , Emanuele Berti , Daniel D'Orazio , Joseph Silk

The James Webb Space Telescope (JWST) has uncovered a ubiquitous population of dust-obscured compact sources at $z\gtrsim 4$. Many of these objects exhibit signs of active galactic nucleus (AGN) activity, making their study crucial for…

We present near- and mid-infrared spectra of eight Low-Luminosity Active Galactic Nuclei (LLAGN), spanning nearly four orders of magnitude in black hole mass and Eddington ratio, obtained with JWST/NIRSpec and MIRI as part of the ReveaLLAGN…

JWST has revealed a population of broad-line active galactic nuclei at $z>4$ with remarkably red colors, so-called "Little Red Dots." Ubiquitous Balmer breaks suggest that they harbor old stellar populations in massive, compact host…

It has been claimed that a fraction of the so-called Little Red Dots (LRDs) are characterised by exponential broad line profiles, which have been ascribed to broadening from electron scattering by an ionised cocoon. In this work, we…

JWST spectroscopy has discovered a population of $z \gtrsim 3.5$ galaxies with broad Balmer emission lines, and narrow forbidden lines, that are consistent with hosting active galactic nuclei (AGN). Many of these systems, now known as…

Low luminosity active galactic nuclei (LLAGN) probe accretion physics in the low Eddington regime and can provide additional clues about galaxy evolution. AGN variability is ubiquitous and thus provides a reliable tool for finding AGN. We…

We present a study of Pseudo-LRD-NOM (Pseudo little red dot with no metal lines), a highly magnified low-mass galaxy behind the lensing cluster Abell 370 at z=5.96. We classify this object as a pseudo-LRD because its red rest-frame optical…

Astrophysics of Galaxies · Physics 2026-01-19 Karina I. Caputi , Ryan A. Cooper , Pierluigi Rinaldi , Rafael Navarro-Carrera , Edoardo Iani

Observations with the James Webb Space Telescope (JWST) have uncovered a substantial population of high-redshift broad-line active galactic nuclei (BLAGNs) characterized by moderate luminosities, weak X-ray emissions, and faint…

High Energy Astrophysical Phenomena · Physics 2026-04-01 Piero Madau

New populations of red active galactic nuclei (known as ``Little Red Dots'') discovered by JWST exhibit remarkable spectral energy distributions. Leveraging X-ray through far-infrared observations of two of the most luminous known Little…

Variability detected in galaxies is usually attributed to their active galactic nuclei (AGNs). While all AGNs are intrinsically variable, the AGN unification model predicts that type~2 AGNs rarely vary because their engines are blocked by…

Astrophysics of Galaxies · Physics 2026-02-17 Bangzheng Sun , Haojing Yan , Wei Leong Tee , Feige Wang

Spatially compact objects with extremely red color in the rest-frame optical to near-infrared (0.4--1 ${\rm \mu m}$) and blue color in the rest-frame ultraviolet (UV; 0.2--0.4 ${\rm \mu m}$) have been discovered at $5 < z < 9$ using the…

Astrophysics of Galaxies · Physics 2023-12-06 Akatoki Noboriguchi , Akio K. Inoue , Tohru Nagao , Yoshiki Toba , Toru Misawa

Little Red Dots (LRDs) are compact sources at $z>5$ discovered through JWST spectroscopy. Their spectra exhibit broad Balmer emission lines ($\gtrsim1000\rm~km~s^{-1}$), alongside absorption features and a pronounced Balmer break --…

Astrophysics of Galaxies · Physics 2026-01-14 Seok-Jun Chang , Max Gronke , Jorryt Matthee , Charlotte Mason

JWST spectroscopy has built large emission line samples at $z\gtrsim4$, but it has yet to confidently reveal many galaxies with the hard radiation fields commonly associated with AGN photoionization. While this may indicate a weaker UV…

JWST surveys have uncovered a population of compact, red sources ("Little Red Dots," LRDs) at $z \ge 5$ that exhibit broad Balmer emission yet remain X-ray faint, implying heavy obscuration with $N_H \ge 10^{24}$ cm$^{-2}$. We propose that…

Astrophysics of Galaxies · Physics 2026-05-29 Tak-Pong Woo