Back From the Dead: The Zombies of the Space Thread

A Black Hole’s Boomerangs

Astronomers have deciphered the dynamics of yet another great trick that monster black holes can play.

In many galaxies, jets of energy are squeezed outward by the black hole that lurks at the center and go shooting off in opposite directions into space.

But in a few bizarre-looking galaxies, the jets take the form of four beams in the shape of an X. Now, radio astronomy observations have shown how that happens.

Astronomers have no trouble understanding how black holes — objects so dense that not even light can escape the tombstone grip of their gravity — can become the most luminous objects in the universe, powering quasars. The pressure in the fat, fiery swirl of doom that surrounds a black hole expels high-energy particles from the top and bottom of the doughnut.

But a galaxy known as PKS 2014-55 is different. This old, elliptical galaxy is about 800 million light-years from Earth in the constellation Telescopium, and its jets are shaped like two boomerangs placed back to back to form an X.

Why? Perhaps, some astronomers thought, the central black hole was wobbling, like a lawn sprinkler throwing jets in different directions. Or maybe a pair of supermassive black holes were colliding.

But observations by an international group of astronomers with a powerful new South African radio telescope, MeerKAT, have provided an alternate explanation.

The dynamics of the jets, it seems, more closely resemble those in an elaborate Las Vegas fountain, with water going up and down and flowing in designer configurations. In this case, superhot gas is being pumped up 2.5 million light-years into intergalactic space. It then cascades back and splashes sideways off the center of the galaxy, sculpting an X in the cosmos, as if marking a treasure.

“Material falls back and gets reflected around the center,” said Fernando Camilo, chief scientist of the South African Radio Astronomy Observatory, which built MeerKAT.

The team, led by William Cotton, an astronomer with the National Radio Astronomy Observatory in the United States, reported its results last week in the Monthly Notices of the Royal Astronomical Society.

Key to the results was the new MeerKAT radio telescope, an array of 64 antennas located in the Karoo desert in South Africa. Computers can combine the data from the individual dishes to create radio images with exquisite detail. MeerKAT was designed and built as a precursor to one of the great dream projects of astronomy, the Square Kilometer Array, a giant assembly of hundreds of radio dishes with a total collecting area of a square kilometer. Half of it is being built in South Africa and half in Australia.

“MeerKAT is one of a new generation of instruments whose power solves old puzzles even as it finds new ones,” Dr. Cotton said in a statement issued by the South African Radio Astronomy Observatory.

In their paper, the scientists described in detail how the fireworks in PKS 2014-55 work.

First, energetic material is launched outward in two opposite directions by the central black hole. But intergalactic space is not empty; it is filled with a thin hot gas. As the jet encounters this gas, it slows and eventually stops. Material from the stalled jet then begins to fall back down into the galaxy from which it came, accumulating around the edges of the main jets like mist tumbling down the outside of a fire hose.

Eventually, the return flow hits the galaxy itself, and the cloud of hot gas that typically inhabits the centers of old galaxies. The pressure of this gas deflects the flow of the returning streams, the way a pebble in a stream redirects the current.

Which way the flow goes from there, Dr. Camilo said, depends on how the ellipse of hot gas is oriented relative to the two returning hydrodynamic flows. In this case, the streams are again steered in opposite directions, creating the two boomerang-shaped features.

“It’s all quite neat,” Dr. Camilo said.

More 'fast radio bursts' have been detected from a distant galaxy. This one has a repeating pattern.

More unexplained signals are coming from outer space, scientists report in a new study.

For only the second time ever, scientists have detected a radio signal from a distant galaxy that repeats at regular intervals.

The series of "fast radio bursts" – short-lived pulses of radio waves that come from across the universe – were detected for 90 days then stopped for a period of 67 days.

The same start-and-stop pattern then repeated every 157 days.

Kaustubh Rajwade of the University of Manchester in the U.K., who led the new research, said in a statement: "This is an exciting result as it is only the second system where we believe we see this modulation in burst activity. Detecting a periodicity provides an important constraint on the origin of the bursts."

This discovery provides an important clue to identifying the origin of these enigmatic bursts, which come from a dwarf galaxy that's some 3 billion light-years away from Earth.

The presence of a regular sequence in the burst activity could imply that the powerful bursts are linked to the orbital motion of a massive star, a neutron star or a black hole, according to the University of Manchester.

First discovered in 2007, fast radio bursts last only a few milliseconds, which makes it difficult to accurately determine where they come from.

"One of the greatest mysteries in astronomy right now is the origin of short, dramatic bursts of radio light seen across the universe," the Max Planck Institute for Radio Astronomy said in a statement earlier this year.

"Although they last for only a thousandth of a second, there are now hundreds of records of these enigmatic sources," the institute said.

Could it be aliens? Almost certainly not, the Massachusetts Institute of Technology said in a recent statement: "The signals are a sign of energetic events that are on the extreme scale of the cosmos. Even a highly intelligent species would be very unlikely to produce energies like this. And there is no detectable pattern so far that would suggest there’s a sentient hand at play."

Speaking about the new research, study co-author Duncan Lorimer of West Virginia University said that “this exciting discovery highlights how little we know about the origin of fast radio bursts."

The study was published Sunday in the peer-reviewed journal Monthly Notices of the Royal Astronomical Society.

Here’s something to look forward to this weekend: Before sunrise on July 19, five planets–Mercury, Venus, Mars, Jupiter, and Saturn–and the crescent moon will all be visible in the sky at the same time. And better yet, you won’t even need a telescope to see them!

The five planets and crescent moon will simultaneously be visible to the naked eye 45 minutes before sunrise on Sunday, July 19, astronomy educator Dr. Jeffrey Hunt wrote in a blog post. They’ll be curved across the morning sky, so you’ll want to “find a spot with clear horizons in the east-northeast and the southwest,” Hunt advises.

How do you recognize which planet is which? Two hours before sunrise, you’ll already be able to spot Jupiter in the southwestern sky with the ringed planet Saturn above it and to the right. Mars, aka the red planet, will be visible in the southeastern horizon. Venus blazes in the eastern sky, and Mercury will be to the right of the moon–which will be very low in the east-northeast, reports Space.com.

Although you don’t need a telescope, a pair of binoculars might help you spot the moon, Mercury, and Jupiter because of how low they will be in the sky. If you’re looking for helpful degree measurements or want to know how to set up your telescope for a closer look, check out more at When the Curves Line Up.

Even the most "muddy" meteorites hold priceless artifacts from the very beginning of our solar system.

Rainbow meteorite discovered in Costa Rica may hold building blocks of life

A small, soft space rock smacked into Costa Rica on April 23, 2019. And it may have carried building blocks for life.

The washing machine-sized clay fireball broke up before landing, . Locals found shards scattered between two villages, La Palmera and Aguas Zarcas. And while meteorites turn up all over Earth, these shards were special; the asteroid that spawned them was a soft remnant of the early solar system, made from the dust from the spinning nebula that would ultimately form our solar system, formed in even older stars. And the meteorites that rained down from the event — collectively called Aguas Zarcas — belong to a rare class called carbonaceous chondrites, which form in the wee hours of the solar system's emergence and are typically packed with carbon. This particular space rock contains complex carbon compounds, likely including amino acids (which join to form proteins and DNA) and perhaps other, even more complex building blocks of life.

While other rocky chunks from the very early solar system became parts of planets, this one remained intact and changed over time only through sunlight-driven chemical reactions that spurred the creation of more and more complex chemical compounds.

An earlier meteor that exploded over Murchison, Australia, in 1969 had similar features. Amino acids discovered in its clay, Joshua Sokol reported in Science, helped spread the idea that life on Earth may have originated from chemicals delivered in meteorites. And like the Murchison meteorite, this Aguas Zarcas fragment contains dust from the ancient, earlier Milky Way, before our sun formed.

Studies of this new meteorite are still incomplete, Sokol wrote. But researchers are excited that they can examine it using modern techniques, looking for complex organic compounds —— maybe even proteins —— that even if they did once exist inside the Murchison meteorite have long since disappeared, degrading in Earth's atmosphere. (The Murchison meteorite very closely resembled Aguas Zarcas, and if Aguas Zarcas contained proteins then Murchison probably did as well, though the opportunity to detect them has been lost.) Already, there's evidence of amino acids in this Aguas Zarcas fragment not found elsewhere on Earth.

Aguas Zarcas shards may offer the most pristine samples yet of the early solar system and pre-solar dust cloud. But landing as they did in the Costa Rican rainforest, Sokol reported, there's still the possibility of contamination.

Down the road, even more pristine samples may become available. The Japanese Hayabusa2 probe, launched in 2014 with the goal of sampling the asteroid Ryugu, is already on its way back with Ryugu dust onboard, a sample that may contain carbonaceous chondrite, Sokol noted. And in 2023, NASA will return its own samples from a similar asteroid, Bennu, which Sokol reported is likely related to Aguas Zarcas.

"These asteroid scraps will be truly pristine, having never touched the atmosphere or sat atop rainforest soil," Sokol wrote.

But for now, Aguas Zarcas is the best source of spacefaring carbon compounds available.

Originally published on Live Science.