Why some galaxies green?

A team of astronomers led by Mischa Schirmer (Mischa Schirmer) of the Gemini Observatory had found sixteen galaxies, the hallmark of which was emitted by their unusual green light.

It all started with the discovery of the galaxy J224024, 1? 092,748 (or J2240) in the constellation of Aquarius, we see the way it was 3.7 billion years ago. On one of the images from the Canada-France-Hawaii Telescope, Mr. Schirmer came across the object, the form of which caused him to petrify, he looked like a galaxy, but it was bright green. This is quite unlike any of the galaxies seen astronomer before something totally unexpected in these days of accumulated vast experience with galaxies. The scientist immediately applied for surveillance findings with a more powerful Very Large Telescope of the European Southern Observatory, to find out what is causing this unusual glow.

 In the center of the galaxy is visible J224024, 1? 092,748 - the first of the green.  It owes its color ionization radiation from a supermassive black hole at the center.  (Here and below illustrate the CFHT.)


In the center of the galaxy is visible J224024, 1? 092,748 — the first of the green. It owes its color ionization radiation from a supermassive black hole at the center. (Here and below illustrate the CFHT.)

Following this discovery, the group looked at the list of nearly a billion galaxies, and found another 16 objects with similar properties, as confirmed by additional observations at the telescope "Gemini-South." These galaxies were so rare that in a cube of space with the edge of the observable universe is 1.3 billion light-years (about 2.2 octillion cubic light-years), on average there is only one such object. A new class of galaxies called "Green Beans» (green bean galaxies) — first, because of the color, and secondly, because they resemble the appearance of the galaxy like "peas", but they are larger.

So what causes such a strange glow? Many ordinary matter around galaxies, supermassive black hole located in the nucleus emits intense X-rays and thus ionizes the gas (oxygen) in the surrounding area, causing it to glow brightly. However, in typical active galaxies such areas are usually small, not more than 10% of the diameter of the galaxy. A surveillance J2240 and another half a dozen "green beans", discovered in the course of research, have shown that they have some reason this area has grown to enormous size and occupies the entire volume of the galaxy. Specifically in J2240 is generally almost the biggest and brightest from all known. Ionised oxygen there glows bright green, which explains the strange color of the galaxy, seen by astronomers.

"These luminous area — fantastic luxury of trying to understand the physics of galaxies. It's like medical thermometer inserted in a distant galaxy — says Mischa Schirmer. — Usually, these areas are small and soft, and are visible only in nearby galaxies. And here they are huge and bright, that despite the great distances, they can be observed in detail. "

Why some galaxies green?


In the center of the galaxy is visible J224024, 1? 092,748 — the first of the green. It owes its color ionization radiation from a supermassive black hole at the center. (Here and below illustrate the CFHT.)

Following this discovery, the group looked at the list of nearly a billion galaxies, and found another 16 objects with similar properties, as confirmed by additional observations at the telescope "Gemini-South." These galaxies were so rare that in a cube of space with the edge of the observable universe is 1.3 billion light-years (about 2.2 octillion cubic light-years), on average there is only one such object. A new class of galaxies called "Green Beans» (green bean galaxies) — first, because of the color, and secondly, because they resemble the appearance of the galaxy like "peas", but they are larger.

So what causes such a strange glow? Many ordinary matter around galaxies, supermassive black hole located in the nucleus emits intense X-rays and thus ionizes the gas (oxygen) in the surrounding area, causing it to glow brightly. However, in typical active galaxies such areas are usually small, not more than 10% of the diameter of the galaxy. A surveillance J2240 and another half a dozen "green beans", discovered in the course of research, have shown that they have some reason this area has grown to enormous size and occupies the entire volume of the galaxy. Specifically in J2240 is generally almost the biggest and brightest from all known. Ionised oxygen there glows bright green, which explains the strange color of the galaxy, seen by astronomers.

"These luminous area — fantastic luxury of trying to understand the physics of galaxies. It's like medical thermometer inserted in a distant galaxy — says Mischa Schirmer. — Usually, these areas are small and soft, and are visible only in nearby galaxies. And here they are huge and bright, that despite the great distances, they can be observed in detail. "

Why some galaxies green?

Further analysis of additional data obtained in the infrared range, the researchers placed before another mystery. It was found that the black hole at the center of J2240, presumably, ionizing oxygen at a great distance, it is much less active than expected based on the size and brightness of the luminous region. Astronomers believe that the matter is in the inertial reaction of interstellar gas emission SMCHD: luminous area reflect the long-covered state of the central black hole, when the latter were much more active. In the future, a bright green glow in the J2240 will gradually fade, as the residual radiation will pass through the gas clouds and scattered in space.

Galaxies, in which the activity of the central area of fading, as is the J2240, are in a very fast-phase of her life. In the early universe galaxies were generally much more active in their centers quickly "gained weight" massive black holes that swallowed the surrounding stars and gas, and their accretion disks shone brightly, easily making 100 times more light energy than all the stars regular galaxies together. "Light Echoes", similar to that which we see in the J2240, allows astronomers to study the rapid stop the activity of these objects, to understand how, when and why their energy is attenuated, and try to figure out why we see so little of such objects in the younger galaxies . This group, Mr. Schirmer and going to do to complement the data and X-ray spectroscopic observations.

The report on the study will be published in the Astrophysical Journal, and with his preprint is available here.

Prepared according to the European Southern Observatory.

Category: Astronomy and Space

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