Month: September 2022

FEEDBACK LOOP. “In our model, the gas content of massive galaxies is strongly dependent on the radio-mode AGN feedback, which suppresses cooling in massive haloes at low redshift. Low cold gas fractions may retard the loss of angular momentum due to smaller viscosity and thus, the cold gas flow on to the central BH may be suppressed.” (BH = black hole; AGN = active galactic nuclei). https://lnkd.in/d9JV8md View in LinkedIn

APPRECIABLE EFFECT. “Gas accretion on to BHs due to disc instabilities seems to be a non-negligible trigger mechanism for moderately luminous AGN with BH masses 10(7) < M• < 10(8) M⊙ at low redshift.” (BH = black hole; AGN = active galactic nuclei). https://lnkd.in/d9JV8md View in LinkedIn

BACTERIAL IMMUNITY. “Together with the Cas enzymes of the CRISPR system, these spacers allow the bacteria to recognize non-self DNA and remove it before it is incorporated into the genome. Hence, the bacteria can have "memory" of a previous infiltration, which helps it respond to any future attempts.” The basis of our new-found gene editing ability. https://lnkd.in/dSwmRvM View in LinkedIn

How a feather in the wild, the rain, and mud, can retain such a perfect form has to do with two things: its barbed structure which hooks the pieces in place, and the fine coating of natural water-resistant talcum powder from the bird’s skin. View in LinkedIn

TWO FACTORS. “Our results therefore favour a ‘hybrid’ picture in which major merger events are the main driver of luminous AGN, especially at high redshift, while disc instabilities are the main mechanism powering moderately luminous Seyfert galaxies at low redshift.” (AGN = active galactic nuclei). https://lnkd.in/d9JV8md View in LinkedIn

STELLAR SEEDING. Our model “does not produce enough very luminous QSOs at high redshift (z > 5). Our third, main conclusion is that a heavy seeding mechanism for black holes provides a physically motivated way to increase the predicted number density of very luminous QSOs at high redshift, in line with observations.” (QSO = Quasi Stellar Objects). https://lnkd.in/d9JV8md View in LinkedIn

THE FAILURE OF THE SMALL. “As an implicit consequence of massive black hole seeds, we have also assumed that seeds are not able to form in dark matter haloes below 2 × 10(11) M⊙, as cold gas might not be able to collapse in these haloes due to their shallow potential wells. This simultaneously reduces the number of faint AGN at high redshift, in better agreement with observations.” (AGN = active galactic nuclei; M⊙ = solar masses). https://lnkd.in/d9JV8md View in LinkedIn

COEVOLUTION. “Overall, we conclude that the models presented here provide a plausible attempt to understand the complex scenario of BH and galaxy co-evolution, and to predict the downsizing trend within the framework of hierarchical clustering. However, there still remain many uncertainties in modelling the formation and evolution of BHs, which hopefully ongoing and future observational facilities will help to constrain.” (BH = black hole). https://lnkd.in/d9JV8md View in LinkedIn

PLANET EVOLUTION. “Star formation and black-hole accretion are the key processes that govern how galaxies evolve.” https://lnkd.in/dtZ5f9h View in LinkedIn

SO ENDS this section on black holes, one of the most extreme and fascinating phenomena in cosmology. Obviously, this was but a nibble at the subject, which is enormous and is covered by thousands of papers. Now we transition into how black holes give birth to white holes, their lesser-known offspring. https://lnkd.in/d9JV8md View in LinkedIn