Dec 15

A Curious Cosmic Collision

Source: ESO Photo Release eso1547

eso1547aThe surroundings of the interacting galaxy NGC 5291.
Image credits: ESO

The spectacular aftermath of a 360 million year old cosmic collision is revealed in great detail in new images from ESO’s Very Large Telescope at the Paranal Observatory. Among the debris is a rare and mysterious young dwarf galaxy. This galaxy is providing astronomers with an excellent opportunity to learn more about similar galaxies that are expected to be common in the early Universe, but are normally too faint and distant to be observed by current telescopes. (read more)

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Jun 15

Merging galaxies break radio silence

Source: ESA/Hubble


In the most extensive survey of its kind ever conducted, a team of scientists have found an unambiguous link between the presence of supermassive black holes that power high-speed, radio-signal-emitting jets and the merger history of their host galaxies. Almost all of the galaxies hosting these jets were found to be merging with another galaxy, or to have done so recently. The results lend significant weight to the case for jets being the result of merging black holes and will be presented in the Astrophysical Journal.(read more)

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Mar 14

Spiral galaxy spills blood and guts

Source: ESA/Hubble-HEIC1404

heic1404aNew Hubble image of spiral galaxy ESO 137-001.
Image credits: NASA, ESA. Acknowledgements: Ming Sun (UAH), and Serge Meunier

This new Hubble image shows spiral galaxy ESO 137-001, framed against a bright background as it moves through the heart of galaxy cluster Abell 3627. This cluster is violently ripping the spiral’s entrails out into space, leaving bright blue streaks as telltale clues to this cosmic crime. (read more)

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May 13

Rare merger reveals secrets of galaxy evolution

Source: ESA/Herschel

Massive galaxy merger caught in the act.
Image credits:ESA/NASA/JPL-Caltech/UC Irvine/STScI/Keck/NRAO/SAO.

A rare encounter between two gas-rich galaxies spotted by ESA’s Herschel space observatory indicates a solution to an outstanding problem: how did massive, passive galaxies form in the early Universe? (read more)

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Jun 12

Chance Alignment Mimics a Cosmic Collision

Source: ESA/Hubble Photo Release heic1208

Hubble view of NGC 3314.
Image credits: NASA, ESA, the Hubble Heritage (STScI/AURA)
ESA/Hubble Collaboration, and W. Keel (University of Alabama)

The NASA/ESA Hubble Space Telescope has produced a highly detailed image of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the two just happen to appear in the same direction from our vantage point. (read more)

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Mar 12

VST captures collisions in young galaxy cluster

Source: ESO Photo Release eso1211

A wide variety of interacting galaxies in the young Hercules galaxy cluster.
Image credits:ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute

 The VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile has imaged a fascinating collection of interacting galaxies in the Hercules galaxy cluster. The sharpness of the new picture, and the hundreds of galaxies captured in great detail in less than three hours of observations, attest to the great power of the VST and its huge camera OmegaCAM to explore the nearby Universe. (read more)

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Feb 11

Arp 147: Giant Ring of Black Holes

Source: NASA/Chandra

Arp 147 contains a spiral galaxy (right) that collided with an elliptical galaxy (left), triggering a wave of star formation.
Image credits: X-ray: NASA/CXC/MIT/S.Rappaport et al, Optical: NASA/STScI

Just in time for Valentine's Day comes a new image of a ring -- not of jewels -- but of black holes. This composite image of Arp 147, a pair of interacting galaxies located about 430 million light years from Earth, shows X-rays from the NASA's Chandra X-ray Observatory (pink) and optical data from the Hubble Space Telescope (red, green, blue) produced by the Space Telescope Science Institute (STScI). (read more)

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Jan 11

Identity Parade Clears Cosmic Collisions of the Suspicion of Promoting Black Hole Growth


Image credits: NASA, ESA, M. Cisternas (Max-Planck Institute for Astronomy)

What happens when galaxies crash together? For years, these cosmic collisions have been blamed for triggering violent outbursts at the hearts of galaxies. Now, a remarkable piece of detective work has given a verdict: galactic mergers do not usually whet the appetite of the black holes that power these active galactic nuclei, meaning other, less dramatic phenomena are responsible.(read more)

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May 10

NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activation


Data from an ongoing survey by NASA's Swift satellite have helped astronomers solve a decades-long mystery about why a small percentage of black holes emit vast amounts of energy.

Only about one percent of supermassive black holes exhibit this behavior. The new findings confirm that black holes "light up" when galaxies collide, and the data may offer insight into the future behavior of the black hole in our own Milky Way galaxy. The study will appear in the June 20 issue of The Astrophysical Journal Letters.

The intense emission from galaxy centers, or nuclei, arises near a supermassive black hole containing between a million and a billion times the sun's mass. Giving off as much as 10 billion times the sun's energy, some of these active galactic nuclei (AGN) are the most luminous objects in the universe. They include quasars and blazars. (read more)

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Jan 10

New tidal streams found in Andromeda reveal history of galactic mergers

Source: UC Santa Cruz

M31, the Andromeda Galaxy. Credit: Robert Gendler.

An international team of astronomers has identified two new tidal streams in the Andromeda galaxy, the remnants of dwarf galaxies consumed by our large galactic neighbor.

Analysis of the stars in Andromeda's tidal streams and other components of its extended halo is yielding new insights into the processes involved in the formation and evolution of massive galaxies. (read more)

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Dec 09

IC 4970 and NGC 6872: Galaxy Collision Switches on Black Hole

Source: Chandra X-Ray Observatory

This composite image of data from three different telescopes shows an ongoing collision between two galaxies, NGC 6872 and IC 4970 (roll your mouse over the image above). X-ray data from NASA's Chandra X-ray Observatory is shown in purple, while Spitzer Space Telescope's infrared data is red and optical data from ESO's Very Large Telescope (VLT) is colored red, green and blue. Credit NASA/ESO.

Astronomers think that supermassive black holes exist at the center of most galaxies. Not only do the galaxies and black holes seem to co-exist, they are apparently inextricably linked in their evolution. To better understand this symbiotic relationship, scientists have turned to rapidly growing black holes - so-called active galactic nucleus (AGN) - to study how they are affected by their galactic environments.

The latest data from Chandra and Spitzer show that IC 4970, the small galaxy at the top of the image, contains an AGN, but one that is heavily cocooned in gas and dust. This means in optical light telescopes, like the VLT, there is little to see. X-rays and infrared light , however, can penetrate this veil of material and reveal the light show that is generated as material heats up before falling onto the black hole (seen as a bright point-like source).

Despite this obscuring gas and dust around IC 4970, the Chandra data suggest that there is not enough hot gas in IC 4970 to fuel the growth of the AGN. Where, then, does the food supply for this black hole come from? The answer lies with its partner galaxy, NGC 6872. These two galaxies are in the process of undergoing a collision, and the gravitational attraction from IC 4970 has likely pulled over some of NGC 6872's deep reservoir of cold gas (seen prominently in the Spitzer data), providing a new fuel supply to power the giant black hole. (read more)

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