nonsingular black hole models

[63], The true nature of these objects was initially unknown, and the leading hypothesis was that they originated from the mergers of binary neutron stars[64] or a neutron star with a black hole. Guggenheim fellows. For active galaxies farther away, the width of broad spectral lines can be used to probe the gas orbiting near the event horizon. Furthermore, galaxies with a redshift, z, higher than 0.5 are unsuitable for life as we know it, because of their higher rate of GRBs and their stellar compactness. [note 1]. The nuclear region of the Milky Way, for example, lacks sufficient luminosity to satisfy this condition. It has been hypothesized that a gamma-ray burst in the Milky Way, pointing directly towards the Earth, could cause a mass extinction event.[9]. [39][40] Swift is equipped with a very sensitive gamma-ray detector as well as on-board X-ray and optical telescopes, which can be rapidly and automatically slewed to observe afterglow emission following a burst. Summer School of Space Art with Joe Davis", "Testing Loop Quantum Gravity from Observational Consequences of Nonsingular Rotating Black Holes", Magnetospheric eternally collapsing object, https://en.wikipedia.org/w/index.php?title=Rotating_black_hole&oldid=1118968312, Short description is different from Wikidata, Articles needing additional references from March 2021, All articles needing additional references, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 30 October 2022, at 01:06. [71][64], Most observed events (70%) have a duration of greater than two seconds and are classified as long gamma-ray bursts. There is a 50% chance that such a lethal GRB took place within two kiloparsecs of Earth during the last 500 million years, causing one of the major mass extinction events. On the other hand, the nature of the kind of singularity to be expected inside a black hole remains rather controversial. In 1975, Stephen Hawking argued that, due to quantum effects, black holes "evaporate" by a process now referred to as Hawking radiation in which elementary particles (such as photons, electrons, quarks and gluons) are emitted. First, they deplete ozone, with models showing a possible global reduction of 2535%, with as much as 75% in certain locations, an effect that would last for years. In general relativity, a white hole is a theoretical region of spacetime and singularity that cannot be entered from the outside, although energy-matter, light and information can escape from it. There is an upper limit to how large supermassive black holes can grow. The interaction of this pair with surrounding stars and gas will then gradually bring the SMBH together as a gravitationally bound binary system with a separation of ten parsecs or less. An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not produced by stars.Such excess non-stellar emission has been observed in the radio, microwave, infrared, optical, ultra-violet, X-ray and Appenzeller and Fricke (1972) built models of this behavior, but found that the resulting star would still undergo collapse, concluding that a non-rotating 0.75106M SMS "cannot escape collapse to a black hole by burning its hydrogen through the CNO cycle". All observed GRBs have originated from outside the Milky Way galaxy, although a related class of phenomena, soft gamma repeater flares, are associated with magnetars within the Milky Way. Thus, the most likely outcome would be micro black holes. The most widely accepted mechanism for the origin of long-duration GRBs is the collapsar model,[92] in which the core of an extremely massive, low-metallicity, rapidly rotating star collapses into a black hole in the final stages of its evolution. All other variations in the black hole will either escape to infinity or be swallowed up by the black hole. The broadening was due to the gravitational redshift of the light as it escaped from just 3 to 10 Schwarzschild radii from the black hole. [21][22][23][24], The highest energy light observed from a gamma-ray burst was one teraelectronvolt, from GRB 190114C in 2019. The simplest and most natural theory of gravity with torsion is the EinsteinCartan theory. The black hole information paradox is a puzzle that appears when the predictions of quantum mechanics and general relativity are combined. "[4] As pointed out by Raphael Bousso,[5] Thorn observed in 1978 that string theory admits a lower-dimensional description in which gravity emerges from it in what would now be called a holographic way. Depending on the mass during its lifetime, these stellar remnants can take one of three forms: The collapse of the stellar core to a white dwarf takes place over tens of thousands of years, while the star blows off its outer envelope to form a planetary nebula. The infalling and outgoing mass/energy interact only when they cross. Due to the natural limit on maximum speed of motion, this prevents falling objects from crossing the event horizon no matter how close they get to it. The cause of the precursor burst observed in some of these short events may be the development of a resonance between the crust and core of such stars as a result of the massive tidal forces experienced in the seconds leading up to their collision, causing the entire crust of the star to shatter. A gravitational singularity, spacetime singularity or simply singularity is a condition in which gravity is so intense that spacetime itself breaks down catastrophically. Thus, the infalling object is stretched into a thin strip of matter. Modern interest in the concept stems from particle theories, notably the grand unified and superstring theories, which predict [30] Dynamical evidence for a massive dark object was found at the core of the active elliptical galaxy Messier 87 in 1978, initially estimated at 5109M. He noted that the relatively low output of nearby galactic cores implied these were old, inactive quasars. [12] On July 2, 1967, at 14:19 UTC, the Vela 4 and Vela 3 satellites detected a flash of gamma radiation unlike any known nuclear weapons signature. These objects have a typical mass of about 100,000M and are named direct collapse black holes. In 1877, Austrian physicist Ludwig Boltzmann described it more precisely in terms of the number of distinct microscopic states that the particles composing a macroscopic "chunk" of matter could be in, while still looking like the same macroscopic "chunk". [19] In addition, it is somewhat counterintuitive to note that the average density of a SMBH within its event horizon (defined as the mass of the black hole divided by the volume of space within its Schwarzschild radius) can be less than the density of water. The closest observed GRB as of March 2014 was GRB 980425, located 40 megaparsecs (130,000,000ly)[120] away (z=0.0085) in an SBc-type dwarf galaxy. Astronomers are confident that the Milky Way galaxy has a supermassive black hole at its center, 26,000 light-years from the Solar System, in a region called Sagittarius A*[81] because: Infrared observations of bright flare activity near Sagittarius A* show orbital motion of plasma with a period of 4515min at a separation of six to ten times the gravitational radius of the candidate SMBH. Once a body collapses to within its Schwarzschild radius it forms what is called a black hole, meaning a spacetime region from which not even light can escape. Although most galaxies with no supermassive black holes are very small, dwarf galaxies, one discovery remains mysterious: The supergiant elliptical cD galaxy A2261-BCG has not been found to contain an active supermassive black hole, despite the galaxy being one of the largest galaxies known; ten times the size and one thousand times the mass of the Milky Way. Hogan's rules don't have the right limit so they can't be right." In particular, they would come to equilibrium with a thermal gas of photons. This ultraviolet radiation could potentially reach dangerous levels depending on the exact nature and distance of the burst, but it seems unlikely to be able to cause a global catastrophe for life on Earth. A star is born through the gradual gravitational collapse of a cloud of interstellar matter. 't Hooft showed that this field makes a logarithmic tent-pole shaped bump on the horizon of a black hole, and like a shadow, the bump is an alternative description of the particle's location and mass. For the initial model, these values consisted of the angle of the accretion disk's torus to the line of sight and the luminosity of the source. In such case, they would be weakly interacting massive particles; this could explain dark matter. When a gamma-ray burst is pointed towards Earth, the focusing of its energy along a relatively narrow beam causes the burst to appear much brighter than it would have been were its energy emitted spherically. [66][67][68] The mean duration of these events of 0.2 seconds suggests (because of causality) a source of very small physical diameter in stellar terms; less than 0.2 light-seconds (about 60,000km or 37,000 miles four times the Earth's diameter). [1] Under optimal conditions, the Fermi Gamma-ray Space Telescope satellite, launched in June 2008, might detect experimental evidence for evaporation of nearby black holes by observing gamma ray bursts. In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe.The inflationary epoch lasted from 10 36 seconds after the conjectured Big Bang singularity to some time between 10 33 and 10 32 seconds after the singularity. What exactly is it that spins? in conventional thermodynamics only of the Kelvin temperature T and a few additional state variables, such as the pressure.). This is the point at which it has been hypothesized that the known laws of gravity cease to be valid. This mass depends on the temperature and density of the cloud but is typically thousands to tens of thousands of solar masses.[3]. Stephen Hawking described the flight of a fictional astronaut who, passing within a black hole's event horizon, is "stretched like spaghetti" by the gravitational gradient (difference in gravitational force) from head to toe. An object with relatively high entropy is microscopically random, like a hot gas. A rigid body will resist distortion, and internal elastic forces develop as the body distorts to balance the tidal forces, so attaining mechanical equilibrium. If black holes evaporate via Hawking radiation, a supermassive black hole with a mass of 1011 (100 billion) M will evaporate in around 210100 years. For a simplified notion of a wormhole, space can be visualized as a two-dimensional surface. [8][9] Torsion modifies the Dirac equation in the presence of the gravitational field and causes fermion particles to be spatially extended. [16][20], In October 2018, astronomers reported that GRB 150101B and GW170817, a gravitational wave event detected in 2017, may have been produced by the same mechanism the merger of two neutron stars. [90] The reason for this assumption is the Msigma relation, a tight (low scatter) relation between the mass of the hole in the 10 or so galaxies with secure detections, and the velocity dispersion of the stars in the bulges of those galaxies. As an objective measure of the quantity of information, Shannon entropy has been enormously useful, as the design of all modern communications and data storage devices, from cellular phones to modems to hard disk drives and DVDs, rely on Shannon entropy. But if black holes are produced, then the theory of general relativity is proven wrong and does not exist at these small distances. However, J.D. A rotating black hole is a solution of Einstein's field equation. An interstellar cloud of gas will remain in hydrostatic equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force. Principal participants include Sheperd S. Doeleman, Peter Galison, Avi Loeb, Andrew Strominger and Shing-Tung Yau. [45] No two gamma-ray burst light curves are identical,[46] with large variation observed in almost every property: the duration of observable emission can vary from milliseconds to tens of minutes, there can be a single peak or several individual subpulses, and individual peaks can be symmetric or with fast brightening and very slow fading. He concluded that the black hole entropy is directly proportional to the area of the event horizon. They showed that the behavior could be explained by a massive black hole with up to 1010M, or a large number of smaller black holes with masses below 103M. [14] After thorough analysis, the findings were published in 1973 as an Astrophysical Journal article entitled "Observations of Gamma-Ray Bursts of Cosmic Origin". He noted that when Hawking radiation escapes, there is a way in which incoming particles can modify the outgoing particles. This means that black holes would not only absorb photons, but they would also have to emit them in the right amount to maintain detailed balance. [5], The appearance of stars composed of exotic matter and their internal layered structure is unclear since any proposed equation of state of degenerate matter is highly speculative. No physical force, therefore, can prevent a star smaller than 1.0 SR from collapsing to a singularity (at least within the currently accepted framework of general relativity; this does not hold for the EinsteinYang-MillsDirac system). Brown and Marc Henneaux had rigorously proved already in 1986, that the asymptotic symmetry of 2+1 dimensional gravity gives rise to a Virasoro algebra, whose corresponding quantum theory is a 2-dimensional conformal field theory.[18]. This fact has been used to study many aspects of nuclear and condensed matter physics by translating problems in those subjects into more mathematically tractable problems in string theory. elements [16] of an evaporating black hole, and the ETH behavior of matrix elements [17, 18, 19]. In this process, these small black holes radiate away matter. A black hole in the Milky Way, GRS 1915+105, may rotate 1,150 times per second,[6] approaching the theoretical upper limit. If it has a companion star, a white dwarf-sized object can accrete matter from the companion star. The nitrates might in fact be of benefit to some plants. [86], Because their energy is strongly focused, the gamma rays emitted by most bursts are expected to miss the Earth and never be detected. It occurred at the center of a small elliptical galaxy at redshift z = 0.3534.