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Little Red Dots (LRDs) are a new class of compact extragalactic objects, with a v-shaped optical spectral energy distribution breaking close to the Balmer break wavelength, and broad, typically exponentially-shaped lines. They are believed…

Astrophysics of Galaxies · Physics 2025-10-09 G. P. Nikopoulos , D. Watson , A. Sneppen , V. Rusakov , K. E. Heintz , J. Witstok , G. Brammer

Little red dots (LRDs) are a puzzling population of extragalactic sources whose origin is highly debated. In this {work}, we performed a comprehensive stacking analysis of NIRCam, MIRI, and ALMA images of a large and homogeneously selected…

We test whether ``little red dots'' (LRDs) are the dust-reddened, high-inclination counterparts of bluer compact broad-line active galactic nuclei, here referred to as ``little blue dots'' (LBDs), by modeling their relative number densities…

Astrophysics of Galaxies · Physics 2026-05-07 Piero Madau , Roberto Maiolino

James Webb Space Telescope (JWST) has revealed a population of red and compact objects with a unique V-shape SED at z >= 4 known as Little Red Dots (LRDs). Most of the LRDs with existing spectral observations exhibit broad Balmer lines and…

Astrophysics of Galaxies · Physics 2026-01-06 Zijian Zhang , Linhua Jiang , Weiyang Liu , Luis C. Ho , Kohei Inayoshi

The James Webb Space Telescope has detected massive black holes (BHs) with masses of $\sim 10^{6-8}~M_\odot$ within the first billion years of the universe. One of the remarkable findings is the identification of "Little Red Dots" (LRDs), a…

Astrophysics of Galaxies · Physics 2025-07-17 Kohei Inayoshi

Broad emission lines are emitted in the surroundings of supermassive black holes in the centers of active galactic nuclei (AGN). This region is spatially not resolved. We intend to get information on the structure and geometry of this broad…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 W. Kollatschny , M. Zetzl

The James Webb Space Telescope (JWST) observations have revolutionized extragalactic research, particularly with the discovery of little red dots (LRD), which we propose are dust-reddened broad-line active galactic nuclei (AGNs). Their…

Astrophysics of Galaxies · Physics 2025-02-06 Zhengrong Li , Kohei Inayoshi , Kejian Chen , Kohei Ichikawa , Luis C. Ho

Recent observations by the James Webb Space Telescope have uncovered a population of compact, red object ($z\sim 4\text{--}7$) known as little red dots (LRDs). The presence of broad Balmer emission lines indicates active galactic nuclei…

High Energy Astrophysical Phenomena · Physics 2025-11-03 Daisaburo Kido , Kunihito Ioka , Kenta Hotokezaka , Kohei Inayoshi , Christopher M. Irwin

We present spectroscopic observations of 27 active galactic nuclei (AGN) with some of the lowest black hole (BH) masses known. We use the high spectral resolution and small aperture of our Keck data, taken with the Echellette Spectrograph…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Randi R. Ludwig , Jenny E. Greene , Aaron J. Barth , Luis C. Ho

Raman scattering by atomic hydrogen converts the UV continuum around Ly$\beta$ into optical continuum around H$\alpha$, and the basic atomic physics has been discussed in several works on symbiotic stars. We propose that the same process…

Astrophysics · Physics 2016-08-30 Hee-Won Lee , Jong-Hyeun Yun

The population of the Little Red Dots (LRDs) may represent a key phase of supermassive black hole (SMBH) growth. A cocoon of dense excited gas is emerging as key component to explain the most striking properties of LRDs, such as strong…

Little red dots (LRDs) newly discovered with JWST are active galactic nuclei (AGN) that may represent black hole (BH) growth at the earliest cosmic epochs. These sources show puzzling features unlike typical AGNs, including red optical…

Astrophysics of Galaxies · Physics 2026-03-04 Hiroya Umeda , Kohei Inayoshi , Yuichi Harikane , Kohta Murase

The discovery of Little Red Dots (LRDs) -- a population of compact, high-redshift, dust-reddened galaxies -- is one of the most surprising results from JWST. However, the nature of LRDs is still debated: does the near-infrared emission…

Astrophysics of Galaxies · Physics 2024-06-14 Tonima Tasnim Ananna , Ákos Bogdán , Orsolya E. Kovács , Priyamvada Natarajan , Ryan C. Hickox

The James Webb Space telescope has discovered an abundant population of broad line emitters, typical signposts for Active Galactic Nuclei (AGN). Many of these sources have red colors and a compact appearance that has led to naming them…

Astrophysics of Galaxies · Physics 2025-03-05 M. Volonteri , M. Trebitsch , J. E. Greene , Y. Dubois , C. -A. Dong-Paez , M. Habouzit , A. Lupi , Y. Ma , R. S. Beckmann , P. Dayal , R. Schneider

The unprecedented sensitivity of the \textit{James Webb Space Telescope} (\textit{JWST}) has revolutionized our understanding of the early universe. Among the most intriguing \textit{JWST} discoveries are red, very compact objects showing…

Astrophysics of Galaxies · Physics 2025-02-07 Muhammad A. Latif , Ammara Aftab , Daniel J. Whalen , Mar Mezcua

An empirical relation between the broad line region (BLR) size and optical continuum luminosity is often adopted to estimate the BLR size and then the black hole mass of AGNs. However, optical luminosity may not be a good indicator of…

Astrophysics · Physics 2009-11-10 Xue-Bing Wu , R. Wang , M. Z. Kong , F. K. Liu , J. L. Han