Year: 2026
Type: preprint
Abstract: JWST has revealed a substantial population of "Little Red Dots" (LRDs) at $z>4$, challenging conventional AGN frameworks. However, the low-redshift regime remains largely unexplored. In the second paper of the (LRDs)$^2$ series, we present a systematic selection from DESI DR1 and identify 27 LRDs at $z=0.2-0.9$, yielding a number density lower limit of $7.5\times10^{-10}$ cMpc$^{-3}$. We conducted near-IR spectroscopic follow-up observations for 21 of them, revealing their full SED shapes and emission lines. These low-$z$ LRDs share the hallmark properties of their high-$z$ counterparts: compact morphology, V-shaped UV-optical continua, broad Balmer emission with extreme decrements (median H$α$/H$β\sim15$), frequent Balmer absorption (70%), and blackbody-like optical-to-near-IR continua. All have low metallicity, occupy the same regions in the BPT diagram as high-$z$ LRDs, and have softer ionizing spectra than typical AGNs. The consistency between low-$z$ and high-$z$ LRD properties indicates the same physical processes at work. The correlation between broad-line Balmer luminosity and $L_{5100}$ deviates from that of local type-1 AGNs, limiting the direct application of local BH mass calibrations. Ionized [O III] outflows are ubiquitous (78%). One LRD at $z=0.196$, J1717+3807, shows robust long-term variability in $i$ and WISE bands. The optical-to-NIR continua of LRDs reveal a wide range of temperatures $\sim2000-4700$ K (peak $0.6-1.4$ $μ$m), with a subset showing cooler and larger envelopes than those at high $z$. Low-$z$ LRDs serve not only as proximate laboratories for probing the nature of LRDs, but also trace the cosmic evolution of this population from the cosmic dawn to the present day.
Source: arXiv (Cornell University)
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, Smithsonian Institution, U.S. Department of Energy, National Aeronautics and Space Administration, W. M. Keck Foundation, Gordon and Betty Moore Foundation, University of Pennsylvania, Ohio State University, California Institute of Technology, University of Chicago, University of Minnesota, University of Michigan, Johns Hopkins University, University of Notre Dame, University of Portsmouth, Space Telescope Science Institute, National Energy Research Scientific Computing Center, European Space Agency, University of Cambridge, University College London, University of Nottingham, University of Sussex, University of Edinburgh, Queen's University Belfast, Durham University, Deutsche Forschungsgemeinschaft, Chinese Academy of Sciences, Queen's University, Ministério da Ciência, Tecnologia e Inovação, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Financiadora de Estudos e Projetos, Ministerio de Ciencia e Innovación, Istituto Nazionale di Astrofisica, National Central University, Ludwig-Maximilians-Universität München, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Eötvös Loránd Tudományegyetem, Institut de Física d'Altes Energies, Max-Planck-Institut für Astronomie, University of Illinois at Urbana-Champaign, Office of Science, Jet Propulsion Laboratory, Smithsonian Astrophysical Observatory, Science Mission Directorate, Science and Technology Facilities Council, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Division of Astronomical Sciences, High Energy Physics, Integrated Electronics Engineering Center, Binghamton University, Planetary Science Division, Argonne National Laboratory, Fermilab, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, SLAC National Accelerator Laboratory
Awards: G1039895795, G1044631029, G1079818582, G1143651532, G1286236842, G1313983767, G1451874870, G1632040200, G1677143136, G1800429324, G1813527838, G1863003419, G1968183688, G2171960263, G2638771445, G272672434, G3083819904, G3204085874, G3685081974, G387521742, G42916606, G433322167, G4392917094, G4474636675, G4501827968, G4518818167, G498139845, G5076365615, G5159282255, G5252970658, G5826275554, G58316358, G618131832, G6253208238, G6273510985, G6506395156, G6652958823, A NEO SEARCH PROGRAM USING THE PAN-STARRS PS1 TELESCOPETHE GOAL OF THE PROPOSED RESEARCH IS TO USE T, G6756316859, G6876926712, G6936026503, G7060297222, G7187964967, Management and Operations of the National Optical Astronomy Observatory, G7354628648, G7406122311, G759921648, G767601387, G775452760, Pan-STARRS1: Operations; Public Data Release; Education and Outreach, G7861570460, G8210229802, G823181903, G8292014801, G833430883, G8404944017, G8437677540, G8483879465, G8934477357, G969889393, G988696487
OpenAlex ID: W7162113399