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A new type of black hole activity discovered in the dramatic transformation of a galaxy



  quasar.jpg

In the center of some galaxies, supermassive black holes emit huge amounts of light as they consume all the matter around them.


NRAO / AUI / NSF; Dana Berry / SkyWorks / ALMA (ESO / NAOJ / NRAO)

Astronomers have witnessed a handful of galaxies that have undergone sudden, rapid transformations from weak, lethargic states to fiercely bright quasars. The incredibly rapid transitions that have taken place over several months can be caused by a whole new type of black hole activity at the center of these galaxies.

A study published in the Astrophysical Journal on September 18 describes in detail the observation of six low-ionizing galaxies (LINER) that have been "on" within nine months. LINER galaxies are a common anchorage in space, and astronomers have long debated how they form and where their light comes from. Some believe that the weak supermassive black hole in the center gives them their unique properties, but others hypothesize the formation of stars outside the galactic center is the reason for their luminosity.

Using the Zwicky Transient Facility (ZTF), a new camera installed at the Palomar Observatory in California in 2018, a team of researchers is exploring a number of LINER galaxies. ZTF is able to detect cosmic phenomena that are rapidly changing in brightness, as well as objects such as asteroids, which gives astronomers another way to study the mysterious LINER galaxies and any transient deviations. The team also monitors its observations by examining data from the Hubble, Spitzer and Swift telescopes and a handful of observatories based in the United States.

Reviewing the data, they found that LINER galaxies underwent transitions from their "wimpy" state to extremely energetic galaxies, known as quasars, much faster than expected.


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"The theory suggests that the quasar would take thousands of years to get involved, but these observations suggest that it can happen very quickly. That tells us everything is wrong," says Suvi Gesari, assistant professor in Astronomy at the University of Maryland and co-author of the research book, in a statement.

Quasars are so energetic and bright because of the supermassive black holes in their center. Black holes can be billions of times more massive than the sun, and they are insatiable beasts, attracting gas, dust, and debris that circle them with their huge gravitational pull. It is this field of circular debris and debris that falls into the black hole that make the quasars so strikingly bright. Some may be thousands of times brighter than our native galaxy, the Milky Way.

But why did the LINER galaxies spotted by the team go so dramatically from wimpy to wow ? It's a puzzle that has yet to be solved, and why researchers suggest it is a whole new type of black hole activity. However, the data does help confirm that LINER galaxies can house supermassive black holes.

In addition, the team noted that only the gases and debris closest to the galactic center in the LINER galaxies studied were illuminated, while other quasars exhibited brightness far beyond their center.

Perhaps, they hypothesize, we have captured the moments before and after the birth of a quasar. It provides astronomers with a new exciting way to map the evolution of the galaxy.

"It is surprising that any galaxy can change its appearance on a human time scale," said Sarah Frederick, a graduate student at the University of Maryland and the first author of the article. "These changes happen much faster than we can explain with current quasar theory."


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