Tuesday, March 19, 2024

James Webb spots 'baby' quasars or faint little red dots from cosmic dark ages, rewriting story of black holes

Amazing stuff! Maybe the Big Bang is a Big Myth! 😊 What came before the Big Bang?

"... a significant number of faint little red dots, observed in a distant part of the universe. ...
Unlike anything seen by its predecessor, the Hubble Space Telescope, these objects were indistinguishable from normal galaxies until now. The JWST’s advanced infrared capabilities have allowed scientists to determine that these dots are, in fact, miniature versions of extremely massive black holes. ...
One of the biggest puzzles in astronomy is how some SMBH grew to such immense sizes so rapidly. The current laws of physics and our understanding of stellar explosions suggest a maximum growth rate for black holes. Yet the existence of these cosmic giants defies these constraints, raising questions about our fundamental understanding of cosmic evolution. ..."

From the abstract: 
"Characterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and determining their role in cosmic reionization. We perform a spectroscopic search for broad Hα emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slitless spectroscopy from the EIGER and FRESCO surveys. We identify 20 Hα lines at z = 4.2–5.5 that have broad components with line widths from ∼1200–3700 km s−1, contributing ∼30%–90% of the total line flux. We interpret these broad components as being powered by accretion onto SMBHs with implied masses ∼107–8M⊙. In the UV luminosity range MUV,AGN+host = −21 to −18, we measure number densities of ≈10−5 cMpc−3. This is an order of magnitude higher than expected from extrapolating quasar UV luminosity functions (LFs). Yet, such AGN are found in only <1% of star-forming galaxies at z ∼ 5. The number density discrepancy is much lower when compared to the broad Hα LF. The SMBH mass function agrees with large cosmological simulations. In two objects, we detect complex Hα profiles that we tentatively interpret as caused by absorption signatures from dense gas fueling SMBH growth and outflows. We may be witnessing early AGN feedback that will clear dust-free pathways through which more massive blue quasars are seen. We uncover a strong correlation between reddening and the fraction of total galaxy luminosity arising from faint AGN. This implies that early SMBH growth is highly obscured and that faint AGN are only minor contributors to cosmic reionization."

James Webb spots 'baby' quasars from cosmic dark ages, rewriting story of black holes The observation provides a rare glimpse into the early universe, offering clues about the formation and evolution of galaxies.


Figure 1. False-color stamps of the 20 BL Hα emitters at z = 4.2–5.5 identified in this work ordered by their broad-to-total Hα luminosity ratio


No comments: