Tag Archives: supermassive black holes

Is the pole of the Milky Way’s central black hole pointing directly at us?

The uncertainty of science: New data obtained using a constellation of Earth-based telescopes, working as a unit, strongly suggests that the pole of the Milky Way7s supermassive central black hole, dubbed Sagittarius A* (pronounced A-star), is pointing directly at us.

The high quality of the unscattered image has allowed the team to constrain theoretical models for the gas around Sgr A*. The bulk of the radio emission is coming from a mere 300 milllionth of a degree, and the source has a symmetrical morphology. “This may indicate that the radio emission is produced in a disk of infalling gas rather than by a radio jet,” explains Sara Issaoun, graduate student at the Radboud University Nijmegen in the Netherlands, who leads the work and has tested several computer models against the data. “However, that would make Sgr A* an exception compared to other radio emitting black holes. The alternative could be that the radio jet is pointing almost at us”.

The German astronomer Heino Falcke, Professor of Radio Astronomy at Radboud University and PhD supervisor of Issaoun, calls this statement very unusual, but he also no longer rules it out. Last year, Falcke would have considered this a contrived model, but recently the GRAVITY team came to a similar conclusion using ESO’s Very Large Telescope Interferometer of optical telescopes and an independent technique. “Maybe this is true after all”, concludes Falcke, “and we are looking at this beast from a very special vantage point.”

If this is true, it might explain why Sgr A* is generally observed to be one of the quietest central supermassive black holes known. Compared to many others, its flux of emissions is far less.

Hubble films of movie of a jet firing from a black hole

Cool image time! Using images taken by the Hubble Space Telescope over the past two decades astronomers have assembled a movie of the motion of blobs, ejected by a jet from a supermassive black hole at the center of a galaxy.

The jet from NGC 3862 has a string-of-pearls structure of glowing knots of material. Taking advantage of Hubble’s sharp resolution and long-term optical stability, Eileen Meyer of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, matched archival Hubble images with a new, deep image taken in 2014 to better understand jet motions. Meyer was surprised to see a fast knot with an apparent speed of seven times the speed of light catch up with the end of a slower moving, but still superluminal, knot along the string. The resulting “shock collision” caused the merging blobs to brighten significantly.

The movie is below the fold.
» Read more

A giant black hole in a tiny galaxy

The uncertainty of science: Astronomers have unexpectedly discovered a supermassive black hole in the center of a nearby tiny galaxy, comprising almost 18% of the galaxy’s entire mass.

To weigh the beast, the researchers measured the velocity of stars whipping about the galaxy’s centre using an infrared spectrometer on the Gemini North telescope atop Mauna Kea in Hawaii. The high velocity of the stars is best explained by a central black hole that tips the scales at 21 million times the Sun’s mass, concluded Seth’s team. That is more than five times heavier than the black hole at the centre of the Milky Way — even though M60-UCD1 has an estimated diameter of about one-six-hundredth that of our home galaxy.

Previously astronomers had believed that the size of a galaxy would predict the size of its central black hole, and that a galaxy this small would not house such a supermassive object. This find upsets those theories.

A trio of supermassive black holes

Astronomers have discovered a trinary of supermassive black holes at the center of a distant collision of multiple galaxies.

Astronomer Roger Deane of the University of Cape Town in South Africa and his colleagues have been watching a particular quasar, known as SDSS J1502+1115, in the constellation Boötes. Other astronomers had found that the object, located 4.3 billion light-years from Earth, possessed two supermassive black holes, each the center of a large galaxy smashing into another. The black holes are at least 24,000 light-years apart.

Deane wanted to confirm their existence, so he used an intercontinental array of radio dishes that yields even sharper views than the Hubble Space Telescope. Lo and behold, one of the black holes turned out to be two. “We were incredibly surprised,” says Deane, whose team reports its findings online today in Nature.

While the discovery of this system is incredibly cool, this article in the journal Science is surprisingly incorrect on some points, while also missing the main story.
» Read more

Astronomers watch the central supermassive black hole of a galaxy eat something, either a planet or a brown dwarf.

Astronomers watch the central supermassive black hole of a galaxy eat something, either a planet or a brown dwarf.

Astronomers were using Integral to study a different galaxy when they noticed a bright X-ray flare coming from another location in the same wide field-of-view. Using XMM-Newton, the origin was confirmed as NGC 4845, a galaxy never before detected at high energies. Along with Swift and MAXI, the emission was traced from its maximum in January 2011, when the galaxy brightened by a factor of a thousand, and then as it subsided over the course of the year. “The observation was completely unexpected, from a galaxy that has been quiet for at least 20–30 years,” says Marek Nikolajuk of the University of Bialystok, Poland, lead author of the paper in Astronomy & Astrophysics.

By analysing the characteristics of the flare, the astronomers could determine that the emission came from a halo of material around the galaxy’s central black hole as it tore apart and fed on an object of 14–30 Jupiter masses. This size range corresponds to brown dwarfs, substellar objects that are not massive enough to fuse hydrogen in their core and ignite as stars. However, the authors note that it could have had an even lower mass, just a few times that of Jupiter, placing it in the range of gas-giant planets.

All the instruments listed above are orbiting space telescopes. You can read the science paper here.

The biggest black hole yet found, 17 billion times the mass of our sun.

The biggest black hole yet found, 17 billion times the mass of our sun.

The unusual black hole makes up 14 percent of its galaxy’s mass, rather than the usual 0.1 percent. … NGC 1277 [the galaxy] lies 220 million light-years away in the constellation Perseus. The galaxy is only ten percent the size and mass of our own Milky Way. Despite NGC 1277’s diminutive size, the black hole at its heart is more than 11 times as wide as Neptune’s orbit around the Sun.

Based on these measurements, it appears that this black hole is literally eating this galaxy whole.

Astronomers think they have discovered a distant supermassive black hole that is being ejected from its galaxy at a speed of several million miles per hour.

Astronomers think they have discovered a distant supermassive black hole that is being ejected from its galaxy at a speed of several million miles per hour.

Although the ejection of a supermassive black hole from a galaxy by recoil because more gravitational waves are being emitted in one direction than another is likely to be rare, it nevertheless could mean that there are many giant black holes roaming undetected out in the vast spaces between galaxies. “These black holes would be invisible to us,” said co-author Laura Blecha, also of CfA, “because they have consumed all of the gas surrounding them after being thrown out of their home galaxy.”

This conclusion however is not final. The data could also be explained by the spiraling in of two supermassive black holes.

Two newly discovered supermassive black holes weigh in as the heaviest known

Two newly discovered supermassive black holes weigh in as the heaviest known.

One of the newly discovered black holes is 9.7 billion solar masses and is located in the elliptical galaxy NGC 3842, which is the brightest galaxy in the Leo cluster of galaxies that sits 320 million light years away in the direction of the constellation Leo. The second is as large or larger and sits in the elliptical galaxy NGC 4889, which is the brightest galaxy in the Coma cluster about 336 million light years from Earth in the direction of the constellation Coma Berenices.

It is believed that these heavy supermassive black holes are the kind that produced quasars in the early universe.

Astronomers have proposed that the cloud of dust that surrounds about 50% of the supermassive black holes at the center of galaxies comes from destroyed planets

Science better than fiction: Astronomers have proposed that the cloud of dust surrounding about 50% of the supermassive black holes at the center of galaxies comes from planets that were ripped apart and smashed by that black hole.

Collisions between these rocky objects would occur at colossal speeds as large as 1000 km per second, continuously shattering and fragmenting the objects, until eventually they end up as microscopic dust. Dr. Nayakshin points out that this harsh environment – radiation and frequent collisions – would make the planets orbiting supermassive black holes sterile, even before they are destroyed. “Too bad for life on these planets”, he says, “but on the other hand the dust created in this way blocks much of the harmful radiation from reaching the rest of the host galaxy. This in turn may make it easier for life to prosper elsewhere in the rest of the central region of the galaxy.”

An X-ray deep field over six weeks by Chandra finds massive black holes common in early universe

An X-ray deep field image taken over a six week period by Chandra had found that massive black holes are common in early universe.

These results imply that between 30% and 100% of the distant galaxies contain growing supermassive black holes. Extrapolating these results from the relatively small field of view that was observed to the full sky, there are at least 30 million supermassive black holes in the early Universe. This is a factor of 10,000 larger than the estimated number of quasars in the early Universe.