Origin Of Supermassive Black Holes Research Articles

Experimental demonstration of two types of galaxies: matter galaxies and antimatter galaxies

This paper presents a novel analysis of galaxy formation through the lens of the Small Bang Model, which posits the existence of two distinct types of galaxies generated by micro black holes: matter galaxies generated by antimatter supermassive black holes (SMBHs) and antimatter galaxies generated by matter SMBHs. The relationship between the mass of galaxies and their respective SMBHs is explored, leading to the derivation of two specific mass ratios: 918 for matter galaxies and 324 for antimatter galaxies. By using a dataset of 100 galaxies from a reliable source, the research identifies two separate subsets of galaxies with low measurement error, totaling 41 galaxies. Among these, 31 galaxies (77%) are identified as matter galaxies with a mass ratio of 918, while 10 galaxies (23%) are classified as antimatter galaxies with a mass ratio of 324. The analysis reveals that, despite measurement noise, the data aligns closely with the theoretical predictions for these two distinct types of galaxies. The research provides a strong indication that galaxies and their SMBHs are governed by fixed mass relationships, challenging the idea that these relationships are random or nonlinear. This supports the Small Bang Model, which offers a compelling alternative to the Big Bang Model, with no initial singularity and a universe emerging from a low-energy state. The findings suggest that this model not only explains the formation of spiral galaxies but also accounts for the origin of supermassive black holes at the center of each galaxy. Further study is encouraged, as this discovery opens new avenues for understanding the role of antimatter in the universe and the formation of galaxies.

Einstein, tea leaves, meandering rivers, and the origin of supermassive black holes in ekpyrotic universe

Central supermassive black holes are found in most massive galaxies. However, their origin is still poorly understood. Observations of quasars show that many supermassive black holes existed less than 700 million years after the Big Bang. To explain the existence of such black holes with masses comparable to the stellar mass of the host galaxy, just 500 million years after the Big Bang, it is probably necessary to assume that they originated from heavy seeds. In an ekpyrotic universe, a hot Big Bang occurs as a result of the collision of two branes. Quantum fluctuations create ripples on the brane surfaces, leading to spatial variations in the timing of collisions, thereby creating density perturbations that can facilitate the formation of massive black hole seeds. I hypothesize that perhaps Rayleigh–Bénard–Marangoni-type convection in the extra dimension is a more efficient source of macroscopic density perturbations than quantum fluctuations.

Surveying the Onset and Evolution of Supermassive Black Holes at High-z with AXIS

The nature and origin of supermassive black holes (SMBHs) remain an open matter of debate within the scientific community. While various theoretical scenarios have been proposed, each with specific observational signatures, the lack of sufficiently sensitive X-ray observations hinders the progress of observational tests. In this white paper, we present how AXIS will contribute to solving this issue. With an angular resolution of 1.5″ on-axis and minimal off-axis degradation, we designed a deep survey capable of reaching flux limits in the [0.5–2] keV range of approximately 2 × 10−18 erg s−1 cm−2 over an area of 0.13 deg2 in approximately 7 million seconds (7 Ms). Furthermore, we planned an intermediate depth survey covering approximately 2 deg2 and reaching flux limits of about 2 × 10−17 erg s−1 cm−2 in order to detect a significant number of SMBHs with X-ray luminosities (LX) of approximately 1042 erg s−1 up to z∼10. These observations will enable AXIS to detect SMBHs with masses smaller than 105 M⊙, assuming Eddington-limited accretion and a typical bolometric correction for Type II AGN. AXIS will provide valuable information on the seeding and population synthesis models of SMBHs, allowing for more accurate constraints on their initial mass function (IMF) and accretion history from z∼0–10. To accomplish this, AXIS will leverage the unique synergy of survey telescopes such as the JWST, Roman, Euclid, Vera Rubin Telescope, and the new generation of 30 m class telescopes. These instruments will provide optical identification and redshift measurements, while AXIS will discover the smoking gun of nuclear activity, particularly in the case of highly obscured AGN or peculiar UV spectra as predicted and recently observed by the JWST in the early Universe.

Primordial origin of supermassive black holes from axion bubbles

We study a modification of the primordial black hole (PBH) formation model from axion bubbles.We assume that the Peccei-Quinn scalar rolls down in the radial direction from a large field value to the potential minimum during inflation, which suppresses the axion fluctuations and weakens the clustering of PBHs on large scales.We find that the modified model can produce a sufficient number of PBHs that seed the supermassive black holes while avoiding the observational constraints from isocurvature perturbations and angular correlation of the high-redshift quasars.

The origin of supermassive black holes at cosmic dawn

ABSTRACT We investigate the steady spherically symmetric accretion in the combined potential of a central black hole and a dark matter halo. For the halo, we consider a Hernquist and an NFW potential and calculate the critical points of the flow. We find that the trans-sonic solution to the centre is not possible without a black hole, whereas two types of trans-sonic solutions are possible in its presence. We also derive the mass accretion rate for a black hole at the centre of a dark matter halo. Our results indicate two phases of accretion. The first is an initial phase with a low accretion rate that depends on the black hole mass, followed by a second phase with a high accretion rate that depends on the halo mass. In the second phase, the black hole mass increases rapidly to supermassive scales, which explains the existence of quasars at redshift z ≥ 6 and also the supermassive black holes (SMBHs) recently detected by the JWST. Further, we calculate the evolution of the Eddington ratio for growing black holes. The accretion is mostly sub-Eddington except for a short super-Eddington episode when the mass accretion rate transitions from low to high. However, during that episode, the black hole mass is likely inadequate to hinder accretion through radiative feedback.

Magnetic Effects Promote Supermassive Star Formation in Metal-enriched Atomic-cooling Halos

Intermediate-mass black holes (with ≥105 M ⊙) are promising candidates for the origin of supermassive black holes (with ∼109 M ⊙) in the early universe (redshift z ∼ 6). Chon & Omukai first pointed out direct collapse black hole (DCBH) formation in metal-enriched atomic-cooling halos (ACHs), which relaxes the DCBH formation criterion. On the other hand, Hirano et al. showed that magnetic effects promote DCBH formation in metal-free ACHs. We perform a set of magnetohydrodynamical simulations to investigate star formation in magnetized ACHs with metallicities Z/Z ⊙ = 0, 10−5, and 10−4. Our simulations show that the mass accretion rate onto the protostars becomes lower in metal-enriched ACHs than in metal-free ACHs. However, many protostars form from gravitationally and thermally unstable metal-enriched gas clouds. Under such circumstances, the magnetic field rapidly increases as magnetic field lines wind up due to the spin of protostars. The region with the amplified magnetic field expands outwards due to the orbital motion of protostars and the rotation of the accreting gas. The amplified magnetic field extracts angular momentum from the accreting gas, promotes the coalescence of low-mass protostars, and increases the mass growth rate of the primary protostar. We conclude that the magnetic field amplification is always realized in metal-enriched ACHs regardless of the initial magnetic field strength, which affects the DCBH formation criterion. In addition, we find a qualitatively different trend from the previous unmagnetized simulations in that the mass growth rate is maximal for extremely metal-poor ACHs with Z/Z ⊙ = 10−5.

Dynamical instability of collapsed dark matter halos

A self-interacting dark matter halo can experience gravothermal collapse, resulting in a central core with an ultrahigh density. It can further contract and collapse into a black hole, a mechanism proposed to explain the origin of supermassive black holes. We study dynamical instability of the core in general relativity. We use a truncated Maxwell-Boltzmann distribution to model the dark matter distribution and solve the Tolman-Oppenheimer-Volkoff equation. For given model parameters, we obtain a series of equilibrium configurations and examine their dynamical instability based on considerations of total energy, binding energy, fractional binding energy, and adiabatic index. Our numerical results indicate that the core can collapse into a black hole when the fractional binding energy reaches 0.035 with a central gravitational redshift of 0.5. We further show for the instability to occur in the classical regime, the boundary temperature of the core should be at least 10% of the mass of dark matter particles; for a 109 M⊙ seed black hole, the particle mass needs to be larger than a few keV. These results can be used to constrain different collapse models, in particular, those with dissipative dark matter interactions. https://github.com/michaelwxfeng/truncated-Maxwell-Boltzmann.

Origin of supermassive black holes in massive metal-poor protoclusters

ABSTRACT While large numbers of supermassive black holes have been detected at z > 6, their origin is still essentially unclear. Numerical simulations have shown that the conditions for the classical direct collapse scenario are very restrictive and fragmentation is very difficult to be avoided. We thus consider here a more general case of a dense massive protostar cluster at low metallicity (≲10−3 Z⊙) embedded in gas. We estimate the mass of the central massive object, formed via collisions and gas accretion, considering the extreme cases of a logarithmically flat and a Salpeter-type initial mass function. Objects with masses of at least 104 M⊙ could be formed for inefficient radiative feedback, whereas ∼103 M⊙ objects could be formed when the accretion time is limited via feedback. These masses will vary depending on the environment and could be considerably larger, particularly due to the continuous infall of gas into the cloud. As a result, one may form intermediate mass black holes of ∼104 M⊙ or more. Upcoming observations with the James Webb Space Telescope and other observatories may help us to detect such massive black holes and their environment, thereby shedding additional light on such a formation channel.

Neutrino and Axion Astronomy with Dark Matter Experiments

Sensitive dark matter (DM) experiments can be well exploited beyond their designated targets, allowing to explore a breadth of physics topics. As we discuss, future large direct DM detection experiments constitute impressive telescopes, complementary to conventional neutrino detectors. This opens a new window into neutrino astronomy, including puzzles such as the origin of supermassive black holes and topics like supernova forecast. Furthermore, DM experiments can act as effective instruments for multimessenger astronomy. This is well illustrated by exploration of relativistic axions from transient astrophysical sources (e.g. axion star explosions), providing novel signatures as well as possible insights into the axion potential.

Exploring the origin of supermassive black holes with coherent neutrino scattering

Collapsing supermassive stars (M ≳ 3 × 104 M ☉) at high redshifts can naturally provide seeds and explain the origin of the supermassive black holes observed in the centers of nearly all galaxies. During the collapse of supermassive stars, a burst of non-thermal neutrinos is generated with a luminosity that could greatly exceed that of a conventional core collapse supernova explosion. In this work, we investigate the extent to which the neutrinos produced in these explosions can be observed via coherent elastic neutrino-nucleus scattering (CEνNS). Large scale direct dark matter detection experiments provide particularly favorable targets. We find that upcoming \U0001d4aa(100) tonne-scale experiments will be sensitive to the collapse of individual supermassive stars at distances as large as \U0001d4aa(10) Mpc.

Supermassive Star Formation in Magnetized Atomic-cooling Gas Clouds: Enhanced Accretion, Intermittent Fragmentation, and Continuous Mergers

Abstract The origin of supermassive black holes (with ≳109 M ⊙) in the early universe (redshift z ∼ 7) remains poorly understood. Gravitational collapse of a massive primordial gas cloud is a promising initial process, but theoretical studies have difficulty growing the black hole fast enough. We focus on the magnetic effects on star formation that occurs in an atomic-cooling gas cloud. Using a set of three-dimensional magnetohydrodynamic simulations, we investigate the star formation process in the magnetized atomic-cooling gas cloud with different initial magnetic field strengths. Our simulations show that the primordial magnetic seed field can be quickly amplified during the early accretion phase after the first protostar formation. The strong magnetic field efficiently extracts angular momentum from accreting gas and increases the accretion rate, which results in the high fragmentation rate in the gravitationally unstable disk region. On the other hand, the coalescence rate of fragments is also enhanced by the angular momentum transfer due to the magnetic effects. Almost all the fragments coalesce to the primary star, so the mass growth rate of the massive star increases due to the magnetic effects. We conclude that the magnetic effects support the direct collapse scenario of supermassive star formation.

Angular correlation as a novel probe of supermassive primordial black holes

We investigate the clustering property of primordial black holes (PBHs) in a scenario where PBHs can explain the existence of supermassive black holes (SMBHs) at high redshifts. We analyze the angular correlation function of PBHs originating from fluctuations of a spectator field which can be regarded as a representative model to explain SMBHs without conflicting with the constraint from the spectral distortion of cosmic microwave background. We argue that the clustering property of PBHs can give a critical test for models with PBHs as the origin of SMBHs and indeed show that the spatial distribution of PBHs in such a scenario is highly clustered, which suggests that those models may be disfavored from observations of SMBHs although a careful comparison with observational data would be necessary.

Seeding Supermassive Black Holes with Self-interacting Dark Matter: A Unified Scenario with Baryons

Abstract Observations show that supermassive black holes (SMBHs) with a mass of ∼109 M ⊙ exist when the universe is just 6% of its current age. We propose a scenario where a self-interacting dark matter halo experiences gravothermal instability and its central region collapses into a seed black hole. The presence of baryons in protogalaxies could significantly accelerate the gravothermal evolution of the halo and shorten collapse timescales. The central halo could dissipate its angular momentum remnant via viscosity induced by the self-interactions. The host halo must be on high tails of density fluctuations, implying that high-z SMBHs are expected to be rare in this scenario. We further derive conditions for triggering general relativistic instability of the collapsed region. Our results indicate that self-interacting dark matter can provide a unified explanation for diverse dark matter distributions in galaxies today and the origin of SMBHs at redshifts z ∼ 6–7.

Disc fragmentation and intermittent accretion on to supermassive stars

ABSTRACT Supermassive stars (SMSs) with ∼104–105 M⊙ are candidate objects for the origin of supermassive black holes observed at redshift z > 6. They are supposed to form in primordial-gas clouds that provide the central stars with gas at a high accretion rate, but their growth may be terminated in the middle due to the stellar ionizing radiation if the accretion is intermittent and its quiescent periods are longer than the Kelvin–Helmholtz (KH) time-scales at the stellar surfaces. In this paper, we examine the role of the ionizing radiation feedback based on the accretion history in two possible SMS-forming clouds extracted from cosmological simulations, following their evolution with vertically integrated two-dimensional hydrodynamic simulations with detailed thermal and chemical models. The consistent treatment of the gas thermal evolution is crucial for obtaining the realistic accretion history, as we demonstrate by performing an additional run with a barotropic equation of state, in which the fluctuation of the accretion rate is artificially suppressed. We find that although the accretion becomes intermittent due to the formation of spiral arms and clumps in gravitationally unstable discs, the quiescent periods are always shorter than the KH time-scales, implying that SMSs can form without affected by the ionizing radiation.

Formation of supermassive primordial black holes by Affleck-Dine mechanism

We study the supermassive black holes (SMBHs) observed in the galactic centers. Although the origin of SMBHs is not well understood yet, previous studies suggest that seed black holes (BHs) with masses $1{0}^{4\ensuremath{-}5}\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ exist at a high redshift ($z\ensuremath{\sim}10$). We examine whether primordial black holes (PBHs) produced by inhomogeneous baryogenesis can explain those seed black holes. Inhomogeneous baryogenesis is realized in the modified Affleck-Dine mechanism. In this scenario, there is no stringent constraint from cosmic microwave background $\ensuremath{\mu}$-distortion in contrast to the scenario where Gaussian fluctuations collapse into PBHs. It is found that the model can account for the origin of the seed BHs of the SMBHs.

The spins of supermassive black holes

AbstractWe present 1-second cadence, precise optical observations from SOFIA and Palomar of a sample of nearby supermassive black holes. The observations were taken to identify the shortest timescale variability in the nuclear photometry which may be associated with instabilities in the accretion flow in the immediate vicinity of the black hole. The shortest timescale variability, if associated with the radius of the innermost stable circular orbit (ISCO), can then be used to estimate the spin of the black hole. Despite 1% precision photometry, we obtained a non-detection of any significant variability in the nucleus of M32 (Mbh ∼ 2.5 × 106 Mȯ). Given the density of the stellar cusp, this argues for a scenario where 1000 Msun seed black holes formed from the coalescence of less massive black holes, which then accrete the gas produced by stellar interactions/winds. In more luminous systems however, we find a significant deection of variability and present hypotheses to explain the signal and thereby the origin of supermassive black holes.

Cradle of supermassive stars

Cosmological hydrodynamics simulations reveal the possible formation of supermassive stars within metal-free primordial gas haloes. These stars are thought to be the origin of supermassive black holes.

Gravitational stability and fragmentation condition for discs around accreting supermassive stars

Supermassive stars (SMSs) with mass $\sim10^{5}~\rm{M}_{\odot}$ are promising candidates for the origin of supermassive black holes observed at redshift $\gtrsim6$. They are supposed to form as a result of rapid accretion of primordial gas, although it can be obstructed by the time variation caused by circum-stellar disc fragmentation due to gravitational instability. To assess the occurrence of fragmentation, we study the structure of marginally gravitationally unstable accretion discs, by using a steady one-dimensional thin disc model with detailed treatment of chemical and thermal processes. Motivated by two SMS formation scenarios, i.e., those with strong ultraviolet radiation background or with large velocity difference between the baryon and the dark matter, we consider two types of flows, i.e., atomic and molecular flows, respectively, for a wide range of the central stellar mass $10-10^5~\rm{M}_{\odot}$ and the accretion rate $10^{-3}-1~\rm{M}_{\odot}~\rm{yr}^{-1}$. In the case of a mostly atomic gas flowing to the disc outer boundary, the fragmentation condition is expressed as the accretion rate being higher than the critical value of $10^{-1}~\rm{M}_{\odot}~\rm{yr}^{-1}$ regardless of the central stellar mass. On the other hand, in the case of molecular flows, there is a critical disc radius outside of which the disc becomes unstable. Those conditions appears to be marginally satisfied according to numerical simulations, suggesting that disc fragmentation can be common during SMS formation.

Observational signatures of massive black hole formation in the early Universe

Space telescope observations of massive black holes during their formation may be key to understanding the origin of supermassive black holes and high-redshift quasars. To create diagnostics for their detection and confirmation, we study a simulation of a nascent massive, so-called direct-collapse, black hole that induces a wave of nearby massive metal-free star formation, unique to this seeding scenario and to very high redshifts. Here we describe a series of distinct colors and emission line strengths, dependent on the relative strength of star formation and black hole accretion. We predict that the forthcoming James Webb Space Telescope might be able to detect and distinguish a young galaxy that hosts a direct-collapse black hole in this configuration at redshift 15 with as little as a 20,000-second total exposure time across four filters, critical for constraining supermassive black hole seeding mechanisms and early growth rates. We also find that a massive seed black hole produces strong, H$_2$-dissociating Lyman-Werner radiation.

Music from the heavens – gravitational waves from supermassive black hole mergers in the EAGLE simulations

We estimate the expected event rate of gravitational wave signals from mergers of supermassive black holes that could be resolved by a space-based interferometer, such as the Evolved Laser Interferometer Space Antenna (eLISA), utilising the reference cosmological hydrodynamical simulation from the EAGLE suite. These simulations assume a $\Lambda$CDM cosmogony with state-of-the-art subgrid models for radiative cooling, star formation, stellar mass loss, and feedback from stars and accreting black holes. They have been shown to reproduce the observed galaxy population with unprecedented fidelity. We combine the merger rates of supermassive black holes in EAGLE with the latest phenomenological waveform models to calculate the gravitational waves signals from the intrinsic parameters of the merging black holes. The EAGLE models predict $\sim2$ detections per year by a gravitational wave detector such as eLISA. We find that these signals are largely dominated by mergers between seed mass black holes merging at redshifts between $z\sim2$ and $z\sim1$. In order to investigate the dependence on the assumed black hole seed mass, we introduce an additional model with a black hole seed mass an order of magnitude smaller than in our reference model. We also consider a variation of the reference model where a prescription for the expected delays in the black hole merger timescale has been included after their host galaxies merge. We find that the merger rate is similar in all models, but that the initial black hole seed mass could be distinguished through their detected gravitational waveforms. Hence, the characteristic gravitational wave signals detected by eLISA will provide profound insight into the origin of supermassive black holes and the initial mass distribution of black hole seeds.