We study the stability and possible fates of little red dots (LRDs) under the stellar-only interpretation of their observational features. This is performed by a combination of analyzing the relevant timescales in their stellar dynamics and also the application of recent numerical results on the evolution of the densest stellar systems. We find that these objects typically have tage ∼ tcoll < trelax and are therefore in an unexplored regime never observed before for a stellar system and are potentially highly unstable to runaway collisions. We study different scenarios for the evolution of LRDs and conclude that in a fair fraction of those systems, the formation of a massive black hole (MBH) by runaway stellar collisions seems unavoidable, in all the possibilities studied within the stellar-only interpretation. This evolutionary path would naturally explain many of the problematic characteristics of Little Red Dots, including that these objects are probably transient in the history of the Universe, that most of them would not emit X-rays since they would not yet have become MBHs, and once they do, they would constitute a significant portion of the mass of LRDs. We conclude that LRDs are the most favorable known places to find a recently formed MBH seed or, in the process of formation, that are most probably formed directly within the supermassive range.

On the fate of little red dots / Escala, A., Zimmermann, L., Valdebenito, S., Vergara, M.C., Schleicher, D.R.G., Liempi, M.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 1538-4357. - 995:1(2025), pp. 44-50. [10.3847/1538-4357/ae200e]

On the fate of little red dots

Matias Liempi
2025

Abstract

We study the stability and possible fates of little red dots (LRDs) under the stellar-only interpretation of their observational features. This is performed by a combination of analyzing the relevant timescales in their stellar dynamics and also the application of recent numerical results on the evolution of the densest stellar systems. We find that these objects typically have tage ∼ tcoll < trelax and are therefore in an unexplored regime never observed before for a stellar system and are potentially highly unstable to runaway collisions. We study different scenarios for the evolution of LRDs and conclude that in a fair fraction of those systems, the formation of a massive black hole (MBH) by runaway stellar collisions seems unavoidable, in all the possibilities studied within the stellar-only interpretation. This evolutionary path would naturally explain many of the problematic characteristics of Little Red Dots, including that these objects are probably transient in the history of the Universe, that most of them would not emit X-rays since they would not yet have become MBHs, and once they do, they would constitute a significant portion of the mass of LRDs. We conclude that LRDs are the most favorable known places to find a recently formed MBH seed or, in the process of formation, that are most probably formed directly within the supermassive range.
2025
astrophysical black holes; active galactic nuclei; super-Eddington accretion; supermassive black-holes; galaxy evolution
01 Pubblicazione su rivista::01a Articolo in rivista
On the fate of little red dots / Escala, A., Zimmermann, L., Valdebenito, S., Vergara, M.C., Schleicher, D.R.G., Liempi, M.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 1538-4357. - 995:1(2025), pp. 44-50. [10.3847/1538-4357/ae200e]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1771001
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