•   
  •   

Tech & Science Within Months, 6 Quiet Galaxies Became Blazing Quasars And Scientists Don't Know How

04:00  20 september  2019
04:00  20 september  2019 Source:   sciencealert.com

She fled North Korea for a better life. How her lonely, impoverished death became political

She fled North Korea for a better life. How her lonely, impoverished death became political When they heard the news about Han Sung-ok, they gathered from all corners of the capital and other South Korean cities near and far. Most had never met the 42-year-old single mother, who long ago had escaped from North Korea. She and her 6-year-old son Dong-jin had little contact with the outside world in the months leading up to late July, when they were found dead in a low-income Seoul apartment, possibly of starvation. require(["inlineoutstreamAd", "c.

The six galaxies started out as low-ionisation nuclear emission-line region (LINER) galaxies ; in terms of brightness, that's sort-of like being a galactic middle child. Making up a third of all known galaxies , they're brighter than ones with dormant supermassive black holes at the centre, but not as bright as

Researchers at the University of Maryland saw six different galaxies that are usually quiet had fired up into active quasars in a matter of months . These LINER galaxies are characterised by the mild activity at their nucleus much lower than quasars .

Compared to our brief human lives, we tend to think of events on galactic scales as ones that happen extremely slowly. But that's not always the case.

In a spectacular fashion, six galaxies have just undergone a huge transformation in a matter of mere months. They've gone from relatively peaceful galaxies to active quasars - the brightest of all galaxies, blasting vast amounts of radiation out into the Universe.

This isn't just amazingly cool - these events could help to resolve a long-standing debate about what produces the light in a particular type of galaxy. In fact, they may indicate a previously unknown type of galactic nucleus activity.

Skeletons dubbed the 'Lovers of Modena' were both MEN: Scientists now think 'couple' intentionally buried hand in hand in ancient Italian tomb were brothers, cousins or soldiers who died together in battle

Skeletons dubbed the 'Lovers of Modena' were both MEN: Scientists now think 'couple' intentionally buried hand in hand in ancient Italian tomb were brothers, cousins or soldiers who died together in battle The sex of the pair (pictured), known as the Lovers of Modena, could not be determined when they were unearthed in Italy in 2009 because they were so badly preserved. But using a new technique, researchers were able to test the protein on tooth enamel to reveal the 4-6th Century AD skeletons were male.

Astronomers watch six galaxies suddenly fire up into quasars . Astronomers have spotted fairly quiet , LINER galaxies (left) fire up into quasars (right) in a matter of months . The galaxies in question started off in a class known as low-ionization nuclear emission line region (LINER) galaxies .

They are heavier than stellar mass black holes but lighter than supermassive black holes often located at the centers of galaxies . First Stars Formed Too Fast For Our Cosmological Models, New Evidence Shows Within Months , 6 Quiet Galaxies Became Blazing Quasars and Scientists Don ’ t Know

a star in the sky: The sombrero galaxy is an example of a LINER galaxy. © NASA/ESA and The Hubble Heritage Team (STScI/AURA) The sombrero galaxy is an example of a LINER galaxy.

The six galaxies started out as low-ionisation nuclear emission-line region (LINER) galaxies; in terms of brightness, that's sort-of like being a galactic middle child.

Making up a third of all known galaxies, they're brighter than ones with dormant supermassive black holes at the centre, but not as bright as active galaxies (known as Seyfert galaxies), whose supermassive black holes are chowing down on cosmic snacks.

Now, quasar galaxies are the brightest of such active galaxies; in fact, they are among the brightest objects in the Universe. The light and radio emissions we see are caused by material around the black hole, called an accretion disc.

The universe might be 2 BILLION years younger than scientists have thought, new study suggests

The universe might be 2 BILLION years younger than scientists have thought, new study suggests A study from the Max Planck Institute uses a new technique to come up with a rate that the universe is expanding that is nearly 18% higher than the number scientists had been using since 2000.

Astronomers have observed six galaxies undergoing a sudden and violent transformation — changing from quiet calm galaxies to powerful All of the surprising changes were observed by the automated sky survey project the Zwicky Transient Facility (ZTF) during the first nine months of its operation.

Scientists say Milky Way’s Sagittarius A* has been more active in recent months . “It’s usually a pretty quiet , wimpy black hole on a diet. We don ’ t know what is driving this big feast.” But it is possible to detect radiation blazing from gas and dust just outside the “event horizon” as they are

Pictures: Spectacular photos from space 

That disc contains dust and gas swirling at tremendous speeds like water going down a drain, generating immense friction as it's pulled by the massive gravitational force of the black hole in the centre. This friction produces intense heat and light; vast jets spewed from the black hole's polar regions emit radio waves.

Meanwhile, there's been a long-standing debate over what exactly produces light in LINER galaxies. Some astronomers believe it's produced by black holes; others think that it's the result of copious starburst activity - that is, lots of stars being born.

But, when a team of astronomers led by astronomer Sara Frederick of the University of Maryland went over the first nine months' worth of data from the Zwicky Transient Facility automated sky survey, they found six LINER galaxies doing something… odd.

"For one of the six objects, we first thought we had observed a tidal disruption event, which happens when a star passes too close to a supermassive black hole and gets shredded," Frederick said.

"But we later found it was a previously dormant black hole undergoing a transition that astronomers call a 'changing look,' resulting in a bright quasar. Observing six of these transitions, all in relatively quiet LINER galaxies, suggests that we've identified a totally new class of active galactic nucleus."

Changing-look transitions are not uncommon, but nor are they usually this dramatic. The first changing-look quasar, in fact, wasn't reported until 2015, and then it was in the opposite direction - a quasar dimming into a Seyfert galaxy.

Moreover, such changing-look transitions are usually observed occurring between different types of Seyfert galaxies, which produce different types of light. This light usually depends on the orientation of the galaxy - edge-on, or with the full disc facing us - so these transitions are a mystery unto themselves (and hopefully to be explained another day).

These Seyfert transitions were what the team set out to study.

"Instead, we found a whole new class of active galactic nucleus capable of transforming a wimpy galaxy to a luminous quasar," said astronomer Suvi Gezari of the University of Maryland.

"Theory suggests that a quasar should take thousands of years to turn on, but these observations suggest that it can happen very quickly. It tells us that the theory is all wrong. We thought that Seyfert transformation was the major puzzle. But now we have a bigger issue to solve."

None of the galaxies have particularly active star formation - the most active is producing the equivalent of 1.27 Suns every year. Other surveys have revealed that many (but certainly not all) LINER galaxies don't seem to have high star formation rates, too.

That doesn't mean that the six galaxies are indicative of all LINER galaxies with low star formation. It could mean that they are a different class of galaxy altogether.

But the findings also mean that what we knew about quasars could be wrong, too. The fact that these galaxies could change so dramatically so quickly - on human timescales - is inconsistent with current quasar theory. Whatever can cause such an extreme change must be pretty intense.

"These six transitions were so sudden and dramatic, it tells us that there is something altogether different going on in these galaxies," Frederick said.

"We want to know how such massive amounts of gas and dust can suddenly start falling into a black hole. Because we caught these transitions in the act, it opens up a lot of opportunities to compare what the nuclei looked like before and after the transformation."

Intriguing.

UAE's reserve astronaut will go to ISS 'in near future' .
Plans for sending the next UAE astronaut to the ISS have already been set in motion.Plans for sending the next UAE astronaut to the ISS have already been set in motion, according to the chairman of the UAE Space Agency, Ahmed bin Abdullah Al Falasi.

usr: 1
This is interesting!