Instruct: Given a question, retrieve relevant documents that answer the question.
Query: Do super massive black holes merge?
Almost every galaxy has a black hole with a mass of one million to one billion times that of the sun. A super-massive black hole, of more than 4 million solar masses, is located in the center of our own Milky Way galaxy. As the universe has evolved, galaxies often collide and merge, creating larger galaxies. This has led to the supposition that galaxies in mid-merge should have a two great black holes (a pair) orbiting one another. Expectations were, that this should be a common observation, hand in hand with mid merge collisions. However, observation has not validated this supposition; only a few orbiting pairs had been found. When observation did not match expectation, this posed problems for theories of how galaxies merge and grow.
A supermassive black hole at the core of a galaxy may serve to regulate the rate of star formation in a galactic nucleus. A black hole that is accreting infalling matter can become active, emitting a strong wind through a collimated relativistic jet. This can limit further star formation. Massive black holes ejecting radio-frequency-emitting particles at near-light speed can also block the formation of new stars in aging galaxies. However, the radio emissions around the jets may also trigger star formation. Likewise, a weaker jet may trigger star formation when it collides with a cloud.
After monitoring stellar orbits around Sagittarius A* for 16 years, Gillessen et al. estimate the object's mass at 4.31 ± 0.38 million solar masses. The result was announced in 2008 and published in "The Astrophysical Journal" in 2009. Reinhard Genzel, team leader of the research, said the study has delivered "what is now considered to be the best empirical evidence that super-massive black holes do really exist. The stellar orbits in the Galactic Center show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt."
(May 2) First visual proof of existence of black holes is published. Suvi Gezari's team in Johns Hopkins University, using the Hawaiian telescope Pan-STARRS 1, record images of a supermassive black hole 2.7 million light-years away that is swallowing a red giant.
Two black holes of between 10 and 20 solar masses each have been discovered, initially with the Very Large Array radio telescope in New Mexico, and corroborated by the Chandra X-ray telescope, in 2012. Their detection implies that gravitational ejection of black holes from clusters is not as efficient as was previously thought, and leads to estimates of a total 5 to 100 black holes within M22. Interactions between stars and black holes could explain the unusually large core of the cluster.
The Hubble Space Telescope, launched in 1990, provided the resolution needed to perform more refined observations of galactic nuclei. In 1994 the Faint Object Spectrograph on the Hubble was used to observe Messier 87, finding that ionized gas was orbiting the central part of the nucleus at a velocity of ±500 km/s. The data indicated a concentrated mass of lay within a span, providing strong evidence of a supermassive black hole. Using the Very Long Baseline Array to observe Messier 106 , Miyoshi et al. (1995) were able to demonstrate that the emission from an HO maser in this galaxy came from a gaseous disk in the nucleus that orbited a concentrated mass of , which was constrained to a radius of 0.13 parsecs. They noted that a swarm of solar mass black holes within a radius this small would not survive for long without undergoing collisions, making a supermassive black hole the sole viable candidate.
The nucleus of the galaxy is active and hosts a low luminosity transition Active Galactic Nucleus (AGN). The most accepted theory for the energy source of AGNs is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 3665 is estimated to be based on the velocity dispersion of the molecular gas around the nucleus , or based on the M-sigma relation.
The standard model for an active galactic nucleus is based upon an accretion disc that forms around a supermassive black hole (SMBH) at the core region of the galaxy. The radiation from an active galactic nucleus results from the gravitational energy of matter as it falls toward the black hole from the disc. In about 10% of these galaxies, a diametrically opposed pair of energetic jets ejects particles from the galaxy core at velocities close to the speed of light. The mechanism for producing these jets is not well understood.
In a paper published October 31, 2018, the discovery of conclusive evidence that Sagittarius A* is a black hole was announced. Using the GRAVITY interferometer and the four telescopes of the Very Large Telescope (VLT) to create a virtual telescope 130 metres in diameter, astronomers detected clumps of gas moving at about 30% of the speed of light. Emission from highly energetic electrons very close to the black hole was visible as three prominent bright flares. These exactly match theoretical predictions for hot spots orbiting close to a black hole of four million solar masses. The flares are thought to originate from magnetic interactions in the very hot gas orbiting very close to Sagittarius A*.
The Event Horizon Telescope (EHT) is a project to create a large telescope array consisting of a global network of radio telescopes and combining data from several very-long-baseline interferometry (VLBI) stations around the Earth. The aim is to observe the immediate environment of the supermassive black hole Sagittarius A* at the center of the Milky Way, as well as the even larger black hole in the supergiant elliptical galaxy Messier 87, with angular resolution comparable to the black hole's event horizon.
Most WR stars, the classical population I type, are now understood as being a natural stage in the evolution of the most massive stars (not counting the less common planetary nebula central stars), either after a period as a red supergiant, after a period as a blue supergiant, or directly from the most massive main-sequence stars. Only the lower mass red supergiants are expected to explode as a supernova at that stage, while more massive red supergiants progress back to hotter temperatures as they expel their atmospheres. Some explode while at the yellow hypergiant or LBV stage, but many become Wolf Rayet stars. They have lost or burnt almost all of their hydrogen and are now fusing helium in their cores, or heavier elements for a very brief period at the end of their lives.
The nucleus of the Sombrero galaxy is classified as a low ionization nuclear emission region (LINER). These are nuclear regions where ionized gas is present, but the ions are only weakly ionized (i.e. the atoms are missing relatively few electrons). The source of energy for ionizing the gas in LINERs has been debated extensively. Some LINER nuclei may be powered by hot, young stars found in star formation regions, whereas other LINER nuclei may be powered by active galactic nuclei (highly energetic regions that contain supermassive black holes). Infrared spectroscopy observations have demonstrated that the nucleus of the Sombrero Galaxy is probably devoid of any significant star formation activity. However, a supermassive black hole has been identified in the nucleus (as discussed in the subsection below), so this active galactic nucleus is probably the energy source that weakly ionizes the gas in the Sombrero Galaxy.
The radio continuum emission along the galaxy's major axis is asymmetrical, being brighter in the southwestern part than in the northeast. But the overall radio surface brightness is on the low side. In the mid-infrared range, the spectrum shows indications of high ionization levels usually associated with an active galactic nucleus. However, optical observations show no signs of an active nucleus, which may just mean it is heavily obscured. Indeed, the amount of ionized matter appears to increase near the core. Although this galaxy lacks a bulge that could supply mass to a supermassive black hole, a large black hole was detected at the core by the Chandra X-ray Observatory in 2012. It is inferred to have a mass of around 10 to 10 times the mass of the Sun. This makes it one of the lowest mass nuclear black holes known.
A supercolony occurs when many ant colonies over a large area unite. They still continue to recognize genetic differences in order to mate, but the different colonies within the super colony avoid aggression. Until 2000, the largest known ant supercolony was on the Ishikari coast of Hokkaidō, Japan. The colony was estimated to contain 306 million worker ants and one million queen ants living in 45,000 nests interconnected by underground passages over an area of . In 2000, an enormous supercolony of Argentine ants was found in Southern Europe (report published in 2002). Of 33 ant populations tested along the stretch along the Mediterranean and Atlantic coasts in Southern Europe, 30 belonged to one supercolony with estimated millions of nests and billions of workers, interspersed with three populations of another supercolony. The researchers claim that this case of unicoloniality cannot be explained by loss of their genetic diversity due to the genetic bottleneck of the imported ants. In 2009, it was demonstrated that the largest Japanese, Californian and European Argentine ant supercolonies were in fact part of a single global "megacolony". This intercontinental megacolony represents the most populous recorded animal society on earth, other than humans. Although a good story, this has proven to be incorrect and no ant colony could reach such an enormous size without the 1 million queen ants collapsing their tiny ant economy due to fighting for the power of the ultimate queen.
O'Dowd studies black holes and quasars by using gravitational lensing. He uses the Hubble Space Telescope to look at distant quasars that line up with nearby galaxies. Those galaxies act like additional lenses on the telescope, allowing scientists to see much closer to the black hole than is otherwise possible.
Theoretical models indicate that if Jupiter had much more mass than it does at present, its atmosphere would collapse, and the planet would shrink. For small changes in mass, the radius would not change appreciably, but above about (1.6 Jupiter masses) the interior would become so much more compressed under the increased pressure that its volume would "decrease" despite the increasing amount of matter. As a result, Jupiter is thought to have about as large a diameter as a planet of its composition and evolutionary history can achieve. The process of further shrinkage with increasing mass would continue until appreciable stellar ignition was achieved, as in high-mass brown dwarfs having around 50 Jupiter masses. Jupiter would need to be about 75 times more massive to fuse hydrogen and become a star.
A supervolcano usually has a large caldera and can produce devastation on an enormous, sometimes continental, scale. Such volcanoes are able to severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. They are the most dangerous type of volcano. Examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupo in New Zealand; Lake Toba in Sumatra, Indonesia; and Ngorongoro Crater in Tanzania. Because of the enormous area they may cover, supervolcanoes are hard to identify centuries after an eruption. Similarly, large igneous provinces are also considered supervolcanoes because of the vast amount of basalt lava erupted (even though the lava flow is non-explosive).
The loosely defined term "supervolcano" has been used to describe volcanic fields that produce exceptionally large volcanic eruptions. Thus defined, the Yellowstone Supervolcano is the volcanic field which produced the latest three supereruptions from the Yellowstone hotspot; it also produced one additional smaller eruption, thereby creating the West Thumb of Yellowstone Lake 174,000 years ago. The three supereruptions occurred 2.1 million, 1.3 million, and approximately 630,000 years ago, forming the Island Park Caldera, the Henry's Fork Caldera, and Yellowstone calderas, respectively. The Island Park Caldera supereruption (2.1 million years ago), which produced the Huckleberry Ridge Tuff, was the largest, and produced 2,500 times as much ash as the 1980 Mount St. Helens eruption. The next biggest supereruption formed the Yellowstone Caldera (~ 630,000 years ago) and produced the Lava Creek Tuff. The Henry's Fork Caldera (1.2 million years ago) produced the smaller Mesa Falls Tuff, but is the only caldera from the Snake River Plain-Yellowstone hotspot that is plainly visible today.
During the decade, many smaller manufacturers could not compete with the Big Three and either went out of business or merged. In 1954, American Motors was formed when Hudson merged with Nash-Kelvinator Corporation in a deal worth almost $200 million, the largest corporate merger in United States history at that time.
This episode documents how gravity has a profound effect across the universe, and Cox seeks out a non-space zero-gravity experience to highlight his point. From the formation of galaxies and stars to the patterns of uplift and erosion seen on Earth, gravity is centrally important. Examples are given, such as the tidal force that captured and locked our moon over time, or more massively in the projected collision between the Andromeda and Milky Way Galaxies. Cox then enters a high-G training centrifuge to show how on Earth, gravity is a relatively weak force, but elsewhere in the Universe it is significantly stronger. In Chaco Culture National Historical Park he refers to Carl Sagan's Cosmos, and its link to a 3-week long supernova in 1054. The almost unimaginable crushing gravitational power of the Crab Pulsar is then contrasted to the distance of an atom's nucleus to its orbiting electrons. Finally, there is a look back at how Einstein's research on gravity has enabled us to better understand how gravity actually works within both "the falling valley" of spacetime and the "event horizon" of black holes.
Water has been detected in interstellar clouds within our galaxy, the Milky Way. Water probably exists in abundance in other galaxies, too, because its components, hydrogen and oxygen, are among the most abundant elements in the universe. Based on models of the formation and evolution of the Solar System and that of other star systems, most other planetary systems are likely to have similar ingredients.
The black holes are an estimated 25,000 light years apart, and thus will take millions of years to collide. Should the two supermassive black holes merge, they will form a single super-supermassive black hole.
Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses () may form. There is general consensus that supermassive black holes exist in the centers of most galaxies.
These statistics have been recently altered. 33 pair of super-massive orbiting black holes were recently discovered. The first 32 pair by the DEEP2 Galaxy Redshift Survey conducted with the Keck II Telescope on Hawaii’s Mauna Kea. This survey determined which black hole was moving toward earth at which time. When the black hole moves toward Earth, its light is blue-shifted, meaning it has a shorter wavelength. Orbiting pairs were identified by looking for instances when one black hole was blueshifted and the other redshifted. The pairs orbit each other at 200 km per second, at several thousand light years apart.
An unexpected result can occur with binary black holes that merge in that the gravitational waves carry momentum and the merging black-hole pair accelerates seemingly violating Newton's third law. The center of gravity can add over 1000 km/s of kick velocity. The greatest kick velocities (approaching 5000 km/s) occur for equal-mass and equal-spin-magnitude black-hole binaries, when the spins directions are optimally oriented to be counter-aligned, parallel to the orbital plane or nearly aligned with the orbital angular momentum. This is enough to escape large galaxies. With more likely orientations a smaller effect takes place, perhaps only a few hundred kilometers per second. This sort of speed will eject merging binary black holes from globular clusters, thus preventing the formation of massive black holes in globular cluster cores. In turn this reduces the chances of subsequent mergers, and thus the chance of detecting gravitational waves. For non spinning black holes a maximum recoil velocity of 175 km/s occurs for masses in the ratio of five to one. When spins are aligned in the orbital plane a recoil of 5000 km/s is possible with two identical black holes.
Parameters that may be of interest include the point at which the black holes merge, the mass ratio which produces maximum kick, and how much mass/energy is radiated via gravitational waves. In a head-on collision this fraction is calculated at 0.002 or 0.2%. One of the best candidates of the recoiled supermassive black holes is CXO J101527.2+625911.