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Cosmic "magnifying glass" used to identify distant colliding galaxies


August 29, 2014

The foreground galaxy can be seen cutting across the lensing light from the distant merging galaxies (Image: ESO/NASA/ESA/W. M. Keck Observatory)

The foreground galaxy can be seen cutting across the lensing light from the distant merging galaxies (Image: ESO/NASA/ESA/W. M. Keck Observatory)

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An international team of astronomers has used a range of telescopes including the Atacama Large Millimeter/submillimeter Array (ALMA) to observe a pair of galaxies colliding at a time when the universe was just half its current age. The project made use of a gravitational magnifying glass created by the gravity of a galaxy between Earth and the subject, and required observations in both visible and infrared light.

The galaxies, known collectively as H-ATLAS J142935.3-002836 (H1429-0028 for short), were originally discovered in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). The system is obscured by a closer galaxy in the foreground, and was found to be extremely faint when viewed in visible light, but appeared much brighter in far-infrared observations.

While the closer, obscuring galaxy created obvious difficulties in directly observing the distant object, the team was able to make use of an effect known as gravitational lensing, wherein a cosmic lens is created by the gravity of a foreground galaxy. This lens deflects the light being emitted from the obscured object, allowing astronomers to study it in detail.

Diagram showing how gravitational lensing deflects light around an obscuring galaxy (Image: ESO/M. Kornmesser)

Knowing that this was possible, a campaign of observations were embarked upon, utilising both space and ground telescopes. NASA/ESA’s Hubble Space Telescope and the Keck Observatory were used to reveal the gravitationally-induced ring of light around the obscuring galaxy, helping to gather details about its nature.

The team then used ALMA and the Karl Jansky Very Large Array (JVLA) to study the area at longer wavelengths, penetrating the intervening clouds of dust. Together, these observations revealed that the obscured system was in fact two galaxies in the process of colliding, the light of which has taken so long reach Earth that, according to astronomers at the European Southern Observatory, the witnessed events actually took place when the universe was around half its current age.

ALMA was particularly useful in identifying the nature of the objects, tracing carbon monoxide to gather information about star formation in the distant galaxies. The telescope’s observations revealed the movement of material in the objects, showing them two be two galaxies, one of which was found to be a disc galaxy, in the process of colliding.

The nature of the colliding galaxies was found to be similar to a much closer object known as the Antennae Galaxies. Though these colliding galaxies are much closer to Earth than H1429-0028, at the time of observation, the more distant object was producing significantly more stars. The distant galaxies annually turn out in excess of 400 times the mass of our Sun of gas into new stars, while the Antennae Galaxies only produce stars equal to one-tenth of the mass of the Sun each year.

Source: ESO

About the Author
Chris Wood Chris specializes in mobile technology for Gizmag, but also likes to dabble in the latest gaming gadgets. He has a degree in Politics and Ancient History from the University of Exeter, and lives in Gloucestershire, UK. In his spare time you might find him playing music, following a variety of sports or binge watching Game of Thrones. All articles by Chris Wood

Nik: I have wondered about that also. And why is ice on a comet if it is in a near vacuum? Wouldn't it turn to gas?

Don Duncan

Question; if the universe is expanding in all directions, how and why do galaxies collide, when they should be moving away from one another?


I hate the fact we still have people practicing politics to keep us in a new Dark Ages.

This article is Science fiction mixed with science fact.

The fact part is being able to OBSERVE the galaxies.

The fiction part is about it birthing stars. No one has observed the actual converging of gases to form a sun - yet this article claims, "The distant galaxies annually turn out in excess of 400 times the mass of our Sun of gas into new stars"

This is as fictional as C-14 dating methods the media lies about being flawless - look into the facts of where C-14 comes from to begin with.

Nik's comment is also very valid. And it should be noted the concept of the expanding universe - another one of those FAKE "proven beyond doubt FACTS" we have been lied to about is being questioned in evolutionary circles - as even is the supposed Big Bang.

Mankind is proving once again his emotional desires, overall, are more important to him than fact, and it keeps the majority of the non-caring populace in their fantasy world. Welcome to manipulation - sad this column supports it.


Just like on the Interstate; they didn't use their turn signals.


It is cold in space, hence the ice instead of vapor. as a comet approaches a sun the material may receive energy and sublimate or the solar wind will carry away some of the comet, much like Halley's comet. Given enough time and orbits the comet will simply wear away.

Theadore J Stone
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