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Descrizione
The James Webb Space Telescope discovered a class of active galactic nuclei (AGNs) missed by previous selections. A fraction of these sources, dubbed "little red dots" (LRDs), show properties that are at odds with “classical” AGNs, and their nature is matter of intense debate. Most of these objects have been found at z > 4. At cosmic dawn (z ~ 6) they are ∼ 1-2 dex more abundant than X-ray and UV-selected AGNs at z ∼ 5 − 7 with similar bolometric luminosity. According to some theories, LRDs may represent the early, rapid growth stages of newly formed black hole (BH) seeds. In this scenario, the abundance of LRDs rapidly decreases from cosmic dawn to cosmic noon, where it is expected to fall short of that of standard AGNs by ∼ 3 dex.
In this talk I will compare the number density of LRDs at cosmic dawn to that at z~2-3, with the latter based on a sample of spectroscopically confirmed LRDs. I will show that this population is still abundant at cosmic noon, with their space density being only a factor of 2-3 lower than that of UV-selected quasars with comparable luminosity. A similar trend is observed in terms of BH masses. This result suggests that the formation of BH seeds can be efficient from cosmic dawn down to cosmic noon.
| Sessione | Evoluzione delle galassie |
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