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<a href="http://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2018/1-transgalacti.jpg "title =" ALMA image reveals how W2246-0526 is being fed by three companion galaxies through the trans-galactic streamers of gas. Credit: ALMA (ESO / NAOJ / NRAO), T. Díaz-Santos et al. S. Dagnello (NRAO / AUI / NSF) ">
ALMA image reveals how W2246-0526 is being fed by three galaxy companions through trans-galactic streamers of gas. The main galaxy and one of its companions are in the center. To the lower left is another companion and its wide tidal tail that connects it to the main galaxy. The upper left is the third such companion galaxy. Credit: ALMA (ESO / NAOJ / NRAO), T. Diaz-Santos et al. S. Dagnello (NRAO / AUI / NSF)
The most luminous galaxy in the universe has been caught in the act of stripping away from half of the mass of its smaller neighbors, according to a new study published in the journal Science. The light from this galaxy, known as W2246-0526, took 12.4 billion years to reach us, so we were able to see it as it was.
New observations with the Atacama Large Millimeter / submillimeter Array (ALMA) revealing distinct streamers of material being drawn from three smaller galaxies and flowing into the more massive galaxy, which was discovered in 2015 by NASA's space-based Wide-field Infrared Survey Explorer (WISE) ). It is unrivaled in its brightness, it is much smaller than 350 trillion Suns.
The connecting tendrils between the galaxies contain as much material as the galaxies themselves. ALMA's amazing resolution and sensitivity allowed the researchers to detect these remarkably faint and distant trans-galactic streamers.
"We know that there were three galaxy companions, but there was no evidence of interactions between these neighbors and the central source," said Tanio Diaz-Santos of the Universidad Diego Portales in Santiago, Chile, lead author of the study. "We were not looking for cannibalistic behavior and were not expecting it, but this deep dive with the ALMA observatory makes it very clear."
Artist print of W2246-0526, the most luminous known galaxy, and three companion galaxies. Credit: NRAO / AUI / NSF, S. Dagnello
Galactic cannibalism is not uncommon, but it is the most distant galaxy in which such behavior is observed and the study is not aware of any other direct images of a galaxy.
The researchers pointed out that the amount of money spent in manufacturing is high enough to keep it going.
This galaxy's startling luminosity is not about its individual stars. Rather, its brightness is powered by a tiny, yet fantastically energetic disk of gas that is being superheated as it spirals in on the supermassive black hole. The light from this blazingly bright accretion disk is then absorbed by the surrounding dust, which re-emits the energy as infrared light.
Composite image of W2246-0526 and its three galaxy companions shown in the ALMA portion of the image (orange). The blue background is an optical image of the same region from Hubble. Credit: ALMA (ESO / NAOJ / NRAO); Diaz-Santos et al .; N. Lira
This extreme infrared radiation makes this galaxy one of a rare class of quasars known as Hot Hot, Dust-Obscured Galaxies or Hot DOGs. Only about one out of every 3,000 quasars observed by WISE belongs to this class.
Much of the dust and gas being siphoned away from the three smaller galaxies is being converted into new stars and feeding the galaxy's central black hole. This galaxy's gluttony, however, may lead to its self-destruction. Previous research suggests that the energy of the AGN would be much more important, if not all of the galaxy's star-forming fuel.
An earlier work led by co-author Chao-Wei Tsai of UCLA estimates that the black hole at the center of W2246-0526 is about 4 billion times the mass of the Sun. The mass of the black hole directly influences how bright the AGN can become, but-according to this earlier research-W2246-0526 is about 3 times more luminous than what should be possible. Solving this apparent contradiction will require additional observations.
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More information:
T. Diaz-Santos et al., The multiple merger assembly of hyperluminous obscured quasar at redshift 4.6, Science (2018). DOI: 10.1126 / science.aap7605
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