Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe Origins and the Early Evolution of Quasars and Supermassive Black Holes
77
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The relationship between galaxies and supermassive black holes (SMBH) found in their cores plays a key role in the formation and evolution of both of these major constituents of the universe, as well as the evolution of the intergalactic medium. Neither can be fully understood on their own, and studies of galaxy and SMBH co-formation and co-evolution are now among the central topics of research in cosmology. Yet the very origins, and the early growth phases of the SMBH are still not firmly established. We review our current understanding of the relevant processes and their astrophysical and cosmological context, with an emphasis on the observability of the SMBH growth mechanisms at high redshifts, and their leftover progeny at low redshifts.
rate research
Read More
The next generation of electromagnetic and gravitational wave observatories will open unprecedented windows to the birth of the first supermassive black holes. This has the potential to reveal their origin and growth in the first billion years, as well as the signatures of their formation history in the local Universe. With this in mind, we outline three key focus areas which will shape research in the next decade and beyond: (1) What were the seeds of the first quasars; how did some reach a billion solar masses before z$sim7$? (2) How does black hole growth change over cosmic time, and how did the early growth of black holes shape their host galaxies? What can we learn from intermediate mass black holes (IMBHs) and dwarf galaxies today? (3) Can we unravel the physics of black hole accretion, understanding both inflows and outflows (jets and winds) in the context of the theory of general relativity? Is it valid to use these insights to scale between stellar and supermassive BHs, i.e., is black hole accretion really scale invariant? In the following, we identify opportunities for the Canadian astronomical community to play a leading role in addressing these issues, in particular by leveraging our strong involvement in the Event Horizon Telescope, the {it James Webb Space Telescope} (JWST), Euclid, the Maunakea Spectroscopic Explorer (MSE), the Thirty Meter Telescope (TMT), the Square Kilometer Array (SKA), the Cosmological Advanced Survey Telescope for Optical and ultraviolet Research (CASTOR), and more. We also discuss synergies with future space-based gravitational wave (LISA) and X-ray (e.g., Athena, Lynx) observatories, as well as the necessity for collaboration with the stellar and galactic evolution communities to build a complete picture of the birth of supermassive black holes, and their growth and their influence over the history of the Universe.
We model the cosmological co-evolution of galaxies and their central supermassive black holes (BHs) within a semi-analytical framework developed on the outputs of the Millennium Simulation (Croton et al., 2006; De Lucia & Blaizot, 2007). In this work, we analyze the model BH scaling relations, fundamental plane and mass function, and compare them with the most recent observational data. Furthermore, we extend the original code developed by Croton et al. (2006) to follow the evolution of the BH mass accretion and its conversion into radiation, and compare the derived AGN bolometric luminosity function with the observed one. We find, for the most part, a very good agreement between predicted and observed BH properties. Moreover, the model is in good agreement with the observed AGN number density in 0<z<5, provided it is assumed that the cold gas fraction accreted by BHs at high redshifts is larger than at low redshifts (Marulli et al., 2008).
The spin angular momentum S of a supermassive black hole (SBH) precesses due to torques from orbiting stars, and the stellar orbits precess due to dragging of inertial frames by the spinning hole. We solve the coupled post-Newtonian equations describing the joint evolution of S and the stellar angular momenta Lj, j = 1...N in spherical, rotating nuclear star clusters. In the absence of gravitational interactions between the stars, two evolutionary modes are found: (1) nearly uniform precession of S about the total angular momentum vector of the system; (2) damped precession, leading, in less than one precessional period, to alignment of S with the angular momentum of the rotating cluster. Beyond a certain distance from the SBH, the time scale for angular momentum changes due to gravitational encounters between the stars is shorter than spin-orbit precession times. We present a model, based on the Ornstein-Uhlenbeck equation, for the stochastic evolution of star clusters due to gravitational encounters and use it to evaluate the evolution of S in nuclei where changes in the Lj are due to frame dragging close to the SBH and to encounters farther out. Long-term evolution in this case is well described as uniform precession of the SBH about the clusters rotational axis, with an increasingly important stochastic contribution when SBH masses are small. Spin precessional periods are predicted to be strongly dependent on nuclear properties, but typical values are 10-100 Myr for low-mass SBHs in dense nuclei, 100 Myr - 10 Gyr for intermediate mass SBHs, and > 10 Gyr for the most massive SBHs. We compare the evolution of SBH spins in stellar nuclei to the case of torquing by an inclined, gaseous accretion disk.
One of the main challenges in using high redshift active galactic nuclei to study the correlations between the mass of the supermassive Black Hole (MBH) and the properties of their active host galaxies is instrumental resolution. Strong lensing magnification effectively increases instrumental resolution and thus helps to address this challenge. In this work, we study eight strongly lensed active galactic nuclei (AGN) with deep Hubble Space Telescope imaging, using the lens modelling code Lenstronomy to reconstruct the image of the source. Using the reconstructed brightness of the host galaxy, we infer the host galaxy stellar mass based on stellar population models. MBH are estimated from broad emission lines using standard methods. Our results are in good agreement with recent work based on non-lensed AGN, demonstrating the potential of using strongly lensed AGNs to extend the study of the correlations to higher redshifts. At the moment, the sample size of lensed AGN is small and thus they provide mostly a consistency check on systematic errors related to resolution for the non-lensed AGN. However, the number of known lensed AGN is expected to increase dramatically in the next few years, through dedicated searches in ground and space based wide field surveys, and they may become a key diagnostic of black hole and galaxy co-evolution.
We use data from the Sloan Digital Sky Survey and visual classifications of morphology from the Galaxy Zoo project to study black hole growth in the nearby Universe (z < 0.05) and to break down the AGN host galaxy population by color, stellar mass and morphology. We find that black hole growth at luminosities L_OIII >1E40 erg/s in early- and late-type galaxies is fundamentally different. AGN host galaxies as a population have a broad range of stellar masses (1E10-1E11 Msun), reside in the green valley of the color-mass diagram and their central black holes have median masses around 1E6.5 Msun. However, by comparing early- and late-type AGN host galaxies to their non-active counterparts, we find several key differences: in early-type galaxies, it is preferentially the galaxies with the least massive black holes that are growing, while late-type galaxies, it is preferentially the most massive}black holes that are growing. The duty cycle of AGN in early-type galaxies is strongly peaked in the green valley below the low-mass end (1E10 Msun) of the red sequence at stellar masses where there is a steady supply of blue cloud progenitors. The duty cycle of AGN in late-type galaxies on the other hand peaks in massive (1E11 Msun) green and red late-types which generally do not have a corresponding blue cloud population of similar mass. At high Eddington ratios (L/L_Edd > 0.1), the only population with a substantial fraction of AGN are the low-mass green valley early-type galaxies. Finally, the Milky Way likely resides in the sweet spot on the color-mass diagram where the AGN duty cycle of late-type galaxies is highest. We discuss the implications of these results for our understanding of the role of AGN in the evolution of galaxies
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
