‘Perfect Storm’ Suffocating Star Formation around a Supermassive Black Hole


High_Resolution

(Click Image to Download)

High-energy jets powered by supermassive black holes can blast away a galaxy’s star-forming fuel — resulting in so-called “red and dead” galaxies: those brimming with ancient red stars yet little or no hydrogen gas available to create new ones.

Now astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that black holes don’t have to be nearly so powerful to shut down star formation. By observing the dust and gas at the center NGC 1266, a nearby lenticular galaxy with a relatively modest central black hole, the astronomers have detected a “perfect storm” of turbulence that is squelching star formation in a region that would otherwise be an ideal star factory.

141217_ALMA_alatalo_01

Fig 1. Artist impression of the central region of NGC 1266. The jets from the central black hole are creating turbulence in the surrounding molecular gas, suppressing star formation in an otherwise ideal environment to form new stars. Credit: B. Saxton (NRAO/AUI/NSF)

This turbulence is stirred up by jets from the galaxy’s central black hole slamming into an incredibly dense envelope of gas. This dense region, which may be the result of a recent merger with another smaller galaxy, blocks nearly 98 percent of material propelled by the jets from escaping the galactic center.

“Like an unstoppable force meeting an immovable object, the molecules in these jets meet so much resistance when they hit the surrounding dense gas that they are almost completely stopped in their tracks,” said Katherine Alatalo, an astronomer with the California Institute of Technology in Pasadena and lead author on a paper published in the Astrophysical Journal. This energetic collision produces powerful turbulence in the surrounding gas, disrupting the first critical stage of star formation. “So what we see is the most intense suppression of star formation ever observed,” noted Alatalo.

Previous observations of NGC 1266 revealed a broad outflow of gas from the galactic center traveling up to 400 kilometers per second. Alatalo and her colleagues estimate that this outflow is as forceful as the simultaneous supernova explosion of 10,000 stars. The jets, though powerful enough to stir the gas, are not powerful enough to give it the velocity it needs to escape from the system.

Continue reading ‘Perfect Storm’ Suffocating Star Formation around a Supermassive Black Hole

Cool gases ideal for star formation in galaxies


universe-wallpaper

Horsehead nebula (Click Image to Download)

Astronomers have discovered that a cool cosmic environment is ideal for the creation of new stars.

A surge of warm gas from a nearby galaxy – left over from the devouring of a separate galaxy – eliminates star formation by agitating the available chilled gas, the study says.

Astronomers wanted to understand why galaxies in the local universe fall into two major categories: younger, star-forming spirals (like our own Milky Way) and older ellipticals in which fresh star making has ceased.

The new study observed galaxy NGC 3226, which occupies a transitional middle ground so getting a lead on its star formation was critical.

“We have explored big data archives from NASA and European Space Agency’s space telescopes to pull together a picture of an elliptical galaxy that has undergone huge changes in its recent past due to violent collisions with its neighbours,” said Philip Appleton, project scientist for the NASA Herschel Science Center at the California Institute of Technology in Pasadena.

These collisions are modifying the condition of the gas that resides in it, making it hard for the galaxy to form many stars, he added.

NGC 3226 is relatively close, just 50 million light-years away from Earth.

The data from the three telescopes finds that NGC 3226 has a very low rate of star formation.

It appears that in this case, the material falling into NGC 3226 is heating up as it collides with other galactic gas and dust, quenching star formation instead of fueling it.

As the warm gas flooding NGC 3226 cools to star-forming temperatures, the galaxy should get a second wind, the authors said.

The paper appeared on Astrophysical Journal.

Source : ZEE NEWS