When the universe was young, massive galaxies formed quickly but surprisingly peacefully. Researchers say they’ve found evidence that these galaxies didn’t grow by sucking up the remnant materials from supernovae or by violent collisions with other galaxies–instead they were fed by streams of cold gas that were funneled into their central star-forming region.
Astronomers using the European Southern Observatory’s Very Large Telescope in Chile have observed three primeval galaxies with patches of star formation near their centers, away from the heavy elements that signal the remains of previous stars. The team found that these galaxies were sucking in cool hydrogen and helium from the space between galaxies as fuel. “It solves the problem of providing to the galaxies fuel to form their stars in a continuous way, without having to invoke violent mergers and galaxy interactions,” said study researcher Giovanni Cresci. [SPACE.com]
The study, published in Nature, describes three galaxies that formed just 2 billion years after the Big Bang–which created lots of hydrogen and helium to feed hungry, growing galaxies, but created few heavier elements. Those formed later in stars and supernovae.
80beats: Hubble Spies Baby Galaxies That Formed Just After the Big Bang
Bad Astronomy: Hubble Sees Ancient Galaxies Rejuvenating Themselves
Bad Astronomy: Hubble Digs Deep to See Baby Galaxies
DISCOVER: Scientists Are Ready to Build Some Galaxies
DISCOVER: Are Black Holes the Architects of the Universe?
Image: L. Calcada (ESO)
If you want to make a supermassive black hole quickly, collide young, massive proto-galaxies. After running the numbers on a supercomputer, that’s what researchers have recently concluded. Their simulation shows that a collision between massive gas clouds could make a black hole “from scratch” in a relatively short time.
Supermassive black hole truly are super massive–possibly billions of times the mass of our sun. They also appear to be super old; some estimates say they formed less than a billion years after the Big Bang. Thus the puzzle, how do you get so big so quickly?
The paper which appeared online yesterday in Nature (with associated letter) modeled the collision of two gas clouds that formed into a unstable gas disk, which channeled gas into its center. Eventually this dense center collapsed in on itself to make the black hole king. (See simulations of the proto-galaxies colliding, above.)
“It has been perplexing how such black holes with masses billions of times the mass of the sun could exist so early in the history of the universe,” astronomer Julie Comerford of University of California Berkeley, who was not involved in the study, wrote in an e-mail to Wired.com. “These simulations are an important advance in understanding how those supermassive black holes were built up so quickly.” [Wired]
One of the top three priorities for the next decade of astrophysics and astronomy, we noted this week, is unraveling dark energy, the weird force that pushes the universe apart. Given that scientists know next-to-nothing about dark energy—besides the fact that it makes up most of the universe—any step could be an important one. Thanks to a study out this week in Science, astrophysicists at least can have more confidence in this phenomenon that can’t be directly seen or measured: Their estimates for dark matter’s extent appear to be on target.
The technique scientists used in this study is called gravitational lensing, and the lens in this case is a huge galactic cluster called Abell 1689.
Because of its huge mass, the cluster acts as a cosmic magnifying glass, causing light to bend around it. The way in which light is distorted by this cosmic lens depends on three factors: how far away the distant object is; the mass of Abell 1689; and the distribution of dark energy [BBC News].
I like the Milky Way. I dare say it’s my favorite galaxy, being home and all. But a blue star called HE 0437-5439 is in one big hurry to leave.
The star is zooming away from the Milky Way’s center at 16 million miles per hour, three times faster than our own sun glides across the galaxy. Astronomers had spotted the hasty traveler before—it’s one of 16 known “hypervelocity” stars. Now, with the help of the Hubble Space Telescope, Warren Brown of the Harvard-Smithsonian Center for Astrophysics traced the path of the star back to the event that allowed it to reach such great speed: a meeting with a black hole.
A hundred million years ago this star was one of three traveling together at a more sedate pace.
The theory of general relativity: It works. OK, it’s not exactly Earth-shattering news that Albert Einstein’s century-old idea works in real life. That’s been shown over and over. But what had been difficult for researchers to do until now was verify the theory on truly massive scales beyond the solar system, that of whole galaxies and clusters of galaxies. This week in Nature, Reinabelle Reyes and colleagues report that they did it, and that Einstein was proven correct once more.
While the find is a nice coup for Reyes’ team, its importance goes beyond just reaffirming the great scientists of yesteryear with yet another “Einstein was right” story. The existence of dark matter and dark energy is based on the assumption that Einstein’s gravity is affecting galaxies billions of light-years from Earth in the same way that it affects objects in our solar system [National Geographic]. However, if the study had shown that general relativity needed a slight adjustment at vast distances (like the nudge Einstein himself provided to Newton’s physics), that could have altered prevailing ideas about dark matter and energy. This research indicates those pesky ideas may be here to stay [Space.com].
Back in December 1995, the Hubble Space Telescope created the now-famous “deep field” image, which took more than 300 exposures over the course of 10 days to peer deep into the history of the universe and spot more than 1,500 galaxies. A decade and a half later—after failures, upgrades, and the “ultra deep field“—Hubble marches on. Yesterday at the American Astronomical Society meeting, astronomers announced they’d used the telescope to look deeper into the past than ever before.
The new image captures 7,500 galaxies of all kinds and shapes. The oldest galaxies in the image glow an intense blue, indicating high concentrations of the lighter elements hydrogen and helium. Hydrogen fusion inside active stars creates heavier elements such as iron and nickel, which get spread across the universe when massive stars explode. These elements cause modern galaxies to glow in a rainbow of colors, so the extreme blueness of the newfound galaxies suggests that they formed before very many massive stars had lived and died [National Geographic News].
Waltzing black holes, star-destroying black holes; it’s a black hole bonanza as the American Astronomical Society meets this week in Washington DC.
First, the orbiting pairs: Just about every galaxy has a supermassive black hole at its heart that is millions if not billions the size of our sun. Logic would suggest that when two galaxies merge, astronomers would see the two great black holes orbiting each other, but so far they’ve had tough luck, astronomer Julie Comerford says. “We expect the universe to be littered with these waltzing black holes,” Comerford said. “But until recently, only a few had ever been found.” Those missing black hole pairs posed problems for theories of how galaxies merge and grow [Wired.com].
Stars and other astronomical phenomena radiate across the electromagnetic spectrum, on both sides of the puny band of visible light that the human eye can pick up. NASA‘s newest toy, set for a Friday launch into space, will map the infrared portion of that radiation—and do it across the entire sky.
The Wide-Field Infrared Survey Explorer, or WISE, has been under construction since 2006. The satellite will spend six months mapping the entire sky in the infrared, after which it will make a second, three-month pass to further refine the mapping [Universe Today]. Stars, galaxies, comets, and other objects will fall under the explorer’s purview.
Which came first: A galaxy or the supermassive black hole at its center? Thanks to a misfit quasar, astronomers have some new clues.
Quasars are particular kinds of black holes that release incredibly intense jets of energy, and scientists spied this one five billion light-years away. To their surprise, the astronomers found that unlike most quasars, this one was ”naked” and not situated at the centre of a galaxy. However, there was a companion galaxy close to it creating new stars at a frantic rate equivalent to about 350 suns per year [The Telegraph].
The Mount Wilson Observatory has allowed astronomers to gaze at the heavens for more than a century from a peak in the San Gabriel Mountains, just northeast of Los Angeles, but the devastating conflagration known as the Station Fire that ripped through the Angeles National Forest over the past week had stargazers wondering if the historic facility was about to go up in smoke. The flames got so close at one point that firefighters abandoned the facility, but now L.A. County Deputy Fire Chief Jim Powers has assured astronomers that he foresees “another hundred years for Mount Wilson Observatory.” This is the story of how firefighters saved the birthplace of modern astronomy as well as a virtual forest of communication towers that serve the region [AP].
On Monday night, the scene was grim. The observatory had been hastily evacuated that day, and only two-dozen firefighters stood overnight sentry, positioned along the gloomy perimeters of the observatory and towers. A greater number might have been deployed, but there were more pressing priorities in the urban elevations — the protection of hillside homes [Los Angeles Times]. By daybreak, fire chiefs made the call to retreat from the mountaintop, where firefighters could easily be trapped by the oncoming flames. “It’s not worth dying for,” said Los Angeles County Fire Department Battalion Chief Steve Martin [Los Angeles Times].