Supermassive Black Holes

Stellar Objects ◽

Massive Black Holes ◽

Quasi Stellar Objects ◽

Age Of The Universe ◽

Luminous Objects ◽

This chapter focuses on supermassive black holes, which are sometimes abbreviated “SMBHs.” Stellar-mass black holes are clearly common consequences of stellar evolution, but they are not the only kinds of black holes identified by astronomers. Much more massive black holes are located in the center of many, and perhaps all, galaxies. These black holes are referred to as supermassive black holes. They are responsible for a range of phenomena originating from objects described as active galactic nuclei (AGN), which were first observed in the form of quasi-stellar objects (QSOs) or quasars. AGN are among the most luminous objects in the Universe and can be observed at great distances. The distances can be so great that the light travel time from the AGN to Earth is a large fraction of the age of the Universe. They are therefore often used to probe the evolution of the Universe.

Co-Evolution of Supermassive Black Holes and Their Host Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310005533 ◽

2009 ◽

Vol 5 (S267) ◽

pp. 34-39

Author(s):

J. K. Kotilainen ◽

R. Decarli ◽

R. Falomo ◽

A. Treves ◽

M. Labita ◽

...

Keyword(s):

Black Holes ◽

Stellar Population ◽

High Redshift ◽

Host Galaxy ◽

Host Galaxies ◽

Massive Black Holes ◽

Galaxy Masses ◽

Age Of The Universe ◽

Black Hole Masses ◽

AbstractWe study the evolution of the MBH/Mhost relation up to z = 3 for a sample of 96 quasars with known host galaxy luminosities. Black hole masses are estimated assuming virial equilibrium in the broad-line regions, while the host galaxy masses are inferred from their luminosities. With this data, we are able to pin down the evolution of the MBH/Mhost relation over 85% of the age of the universe. While the MBH/Lhost relation remains nearly unchanged, taking into account the aging of the stellar population, we find that the MBH/Mhost ratio (Γ) increases by a factor ~ 7 from z = 0 to z = 3. We show that the evolution of Γ is independent of radio loudness and quasar luminosity. We propose that the most massive black holes, in their quasar phase at high-redshift, become extremely rare objects in host galaxies of similar mass in the local universe.

The ecology of the galactic centre: Nuclear stellar clusters and supermassive black holes

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319006689 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 80-83 ◽

Cited By ~ 1

Author(s):

Melvyn B. Davies ◽

Abbas Askar ◽

Ross P. Church

Keyword(s):

Black Holes ◽

Black Hole ◽

Large Fraction ◽

Galactic Nuclei ◽

Galactic Centre ◽

Stellar Clusters ◽

Stellar Cluster ◽

Supermassive Black Hole ◽

Multiple Clusters

AbstractSupermassive black holes are found in most galactic nuclei. A large fraction of these nuclei also contain a nuclear stellar cluster surrounding the black hole. Here we consider the idea that the nuclear stellar cluster formed first and that the supermassive black hole grew later. In particular we consider the merger of three stellar clusters to form a nuclear stellar cluster, where some of these clusters contain a single intermediate-mass black hole (IMBH). In the cases where multiple clusters contain IMBHs, we discuss whether the black holes are likely to merge and whether such mergers are likely to result in the ejection of the merged black hole from the nuclear stellar cluster. In some cases, no supermassive black hole will form as any merger product is not retained. This is a natural pathway to explain those galactic nuclei that contain a nuclear stellar cluster but apparently lack a supermassive black hole; M33 being a nearby example. Alternatively, if an IMBH merger product is retained within the nuclear stellar cluster, it may subsequently grow, e.g. via the tidal disruption of stars, to form a supermassive black hole.

Dark Stars: Dark matter in the first stars leads to a new phase of stellar evolution

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308024575 ◽

2008 ◽

Vol 4 (S255) ◽

pp. 56-60 ◽

Cited By ~ 1

Author(s):

Katherine Freese ◽

Douglas Spolyar ◽

Anthony Aguirre ◽

Peter Bodenheimer ◽

Paolo Gondolo ◽

...

Keyword(s):

Black Holes ◽

Dark Matter ◽

Cross Section ◽

Stellar Evolution ◽

Weakly Interacting Massive Particles ◽

First Stars ◽

History Of ◽

Born Again ◽

The Universe ◽

New Phase

AbstractThe first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the the universe. This talk presents the story of these Dark Stars. We make predictions that the first stars are very massive (~800M⊙), cool (6000 K), bright (~106L⊙), long-lived (~106years), and probable precursors to (otherwise unexplained) supermassive black holes. Later, once the initial DM fuel runs out and fusion sets in, DM annihilation can predominate again if the scattering cross section is strong enough, so that a Dark Star is born again.

The stellar graveyard

Gravitational-Wave Astronomy ◽

10.1093/oso/9780198568032.003.0009 ◽

2019 ◽

pp. 177-206

Author(s):

Nils Andersson

Keyword(s):

Black Holes ◽

General Relativity ◽

Neutron Stars ◽

Gravitational Wave ◽

Stellar Evolution ◽

White Dwarfs ◽

Compact Objects ◽

Fermi Gases ◽

The 1950S

This chapter introduces the different classes of compact objects—white dwarfs, neutron stars, and black holes—that are relevant for gravitational-wave astronomy. The ideas are placed in the context of developing an understanding of the likely endpoint(s) of stellar evolution. Key ideas like Fermi gases and the Chandrasekhar mass are discussed, as is the emergence of general relativity as a cornerstone of astrophysics in the 1950s. Issues associated with different formation channels for, in particular, black holes are considered. The chapter ends with a discussion of the supermassive black holes that are found at the centre of galaxies.

Reionization of the Universe by Early-formed Massive Black Holes

The Astrophysical Journal ◽

10.1086/177131 ◽

1996 ◽

Vol 462 ◽

pp. 104 ◽

Cited By ~ 15

Author(s):

Shin Sasaki ◽

Masayuki Umemura

Keyword(s):

Black Holes ◽

Massive Black Holes ◽

Hipparcos subdwarfs and globular cluster ages: towards reliable absolute ages

Symposium - International Astronomical Union ◽

10.1017/s0074180900116985 ◽

1997 ◽

Vol 189 ◽

pp. 433-438 ◽

Cited By ~ 3

Author(s):

F. Pont ◽

M. Mayor ◽

C. Turon

Keyword(s):

Globular Cluster ◽

Globular Clusters ◽

Large Fraction ◽

Age Determination ◽

Colour Scale ◽

Minimum Age ◽

Age Of The Universe ◽

Robust Prediction ◽

The Universe ◽

Cluster Age

The maximum age of galactic globular clusters provides the best observational constraint on the minimum age of the Universe. One of the main “missing link” in the globular cluster age determination has been the lack of a precise calibration, with local subdwarfs, of the position of the subdwarf sequence at different [Fe/H].Hipparcos data may change this situation. As many precise parallaxes become available for local subdwarfs, the distance to globular clusters can be estimated directly from ZAMS fitting to the subdwarf locus. The ages can then be inferred from the turnoff luminosity (a robust prediction of stellar evolution models), rather than using secondary indicators such as Horizontal-Branch position, or indicators depending on the uncertain colour scale such as turnoff colour.Combining Hipparcos parallaxes with [Fe/H] values determined with the CORAVEL spectrometer, we are studying the position of the subdwarfs in the Colour-Magnitude Diagram from a sample of more than 900 subdwarf candidates. Preliminary results are presented here. It is shown that the distances of many subdwarfs had been underestimated in previous studies, mainly because a large fraction of them is in fact evolved off the main sequence into the turnoff or the subgiant branch.

The Multiwavelength AGN Population and the X-ray Background

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314003731 ◽

2013 ◽

Vol 9 (S304) ◽

pp. 188-194

Author(s):

Ezequiel Treister ◽

Claudia M. Urry ◽

Kevin Schawinski ◽

Brooke D. Simmons ◽

Priyamvada Natarajan ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Mass Density ◽

Large Fraction ◽

X Rays ◽

X Ray ◽

Black Hole Growth ◽

Hole Growth ◽

X Ray Background

AbstractIn order to fully understand galaxy formation we need to know when in the cosmic history are supermassive black holes (SMBHs) growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. Active Galactic Nuclei (AGN) population synthesis models that can explain the spectral shape and intensity of the cosmic X-ray background (CXRB) indicate that most of the SMBH growth occurs in moderate-luminosity (LX~ 1044 erg/s) sources (Seyfert-type AGN), at z~ 0.5−1 and in heavily obscured but Compton-thin, NH~ 1023cm−2, systems. However, this is not the complete history, as a large fraction of black hole growth does not emit significantly in X-rays either due to obscuration, intrinsic low luminosities or large distances. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations. We further investigate the AGN triggering mechanism as a function of bolometric luminosity, finding evidence for a strong connection between significant black hole growth events and major galaxy mergers from z~ 0 to z~ 3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. AGN activity triggered by major galaxies is responsible for ~60% of the total black hole growth. Finally, we constrain the total accreted mass density in supermassive black holes at z > 6, inferred via the upper limit derived from the integrated X-ray emission from a sample of photometrically selected galaxy candidates. We estimate an accreted mass density <1000 M⊙Mpc−3 at z~ 6, significantly lower than the previous predictions from some existing models of early black hole growth and earlier prior observations.

The Influence of Quarks and Gluons Jets Coming from Primordial Black Holes on the Reionization of the Universe

International Journal of Modern Physics A ◽

10.1142/s0217751x97002280 ◽

1997 ◽

Vol 12 (23) ◽

pp. 4167-4198 ◽

Cited By ~ 5

Author(s):

Marina Gibilisco

Keyword(s):

Black Holes ◽

Plasma Heating ◽

Critical Mass ◽

Photon Emission ◽

Plasma Temperature ◽

Primordial Black Holes ◽

Quantum Evaporation ◽

Cooling Effects ◽

Age Of The Universe ◽

In a previous work, I discussed the effect of the primordial black holes (PBH's) quantum evaporation on the reionization of the Universe at small redshifts (z ≤ 60): in principle, the photons emitted during the evaporation of such objects could drive a new ionization for the Universe after the recombination epoch; this reionization process should happen during the last stages of the PBH's life, when they totally evaporate and emit a lot of massive and massless particles. The critical mass of a black hole whose lifetime is equal to the present age of the Universe is ~ 4.4 × 1014 h-0.3 g: thus, PBH's having a mass M ~ 1014 g are the ideal candidates to induce a reionization at small redshifts. While in my previous study, I considered an exact blackbody photon emission spectrum, here I will adopt a more realistic one, taking into account the quarks and gluons jets emission through the contribution of a known fragmentation function. When the BH temperature rises above the QCD confinement scale, ΛQCD, one should expect an important contribution from quarks and gluons emission in the form of jets. In this paper I also improved my analysis by considering without any approximation the cooling effects in the plasma temperature evolution; as a result, I obtained a satisfactory "late and sudden" reionization process, characterized by a very well controlled rise of the plasma temperature: the plasma heating is not so high to induce a strong distortion of the CBR spectrum, in agreement with the recent FIRAS upper limit on the comptonization parameter, yc < 2.5 × 10-5.