Elliptical galaxies much younger than previously thought?

Jul 21, 2011
The galaxy NGC 5557 clearly exhibits extremely extended and faint tidal streams spanning more than 1.2 million light-years from left to right on this image from the MegaCam mounted on the Canada-France-Hawaii Telescope. Image by P.-A. Duc 2011 (c) CEA/CFHT

(PhysOrg.com) -- The standard model for elliptical galaxies formation is challenged by a new result uncovered by an international team of astronomers from the Atlas3D collaboration. Team members from CNRS, CEA, CFHT, and the Observatoire de Lyon published in the scientific journal Monthly Notices of the Royal Astronomical Society the first results from their study on two elliptical galaxies exhibiting features characteristic of a fairly recent merging, suggesting they are five times younger than commonly thought.

The common belief on the mass assembly history of massive based on their stellar population leads to an age between 7 and 10 billion years old. A different story is shaping up based on ultra-deep images of two galaxies observed with the MegaCam camera mounted on the Canada-France-Hawaii Telescope (CFHT, CNRC/CNRS/University of Hawaii).

from CNRS, CEA, CFHT, and the Observatoire de Lyon, all members of the Atlas3D , established that the formation of the two studied elliptical galaxies (NGC 680 & NGC 5557) originated from a merger of two giant spiral galaxies that took place only 1 to 3 billions years ago. Such age estimate is based on the presence of ultra faint filaments in the distant outskirts of the galaxies. These features called tidal streams in the astronomers parlance are typical residuals from a galaxy merger. They are known not to survive in this shape and brightness for more than a few billion years, hence the new age estimate of the resulting elliptical galaxies. These structures were detected for the first time thanks to a very-deep imaging technique boosting the capabilities of CFHT's wide-field optical imager MegaCam.

A sample of elliptical galaxies from the Atlas3D survey current collection, all showing clear signs of a recent collision. Image by P.-A. Duc 2011 (c) CEA/CFHT

The Atlas3D team conducts a systematic survey of more than one hundred nearby elliptical galaxies. If the current result based on the first two galaxies is confirmed on the larger sample, i.e. faint extended features are frequently detected, the for elliptical galaxies formation should be revisited.

Explore further: A new approach in the search for extraterrestrial intelligence: targeting alien polluters

More information: lanl.arxiv.org/pdf/1105.5654

Provided by Canada-France-Hawaii Telescope

4.7 /5 (6 votes)

Related Stories

Most elliptical galaxies are 'like spirals'

Jun 20, 2011

(PhysOrg.com) -- The majority of 'elliptical' galaxies are not spherical but disc-shaped, resembling spiral galaxies such as our own Milky Way with the gas and dust removed, new observations suggest.

Large galaxies stopped growing 7 billion years ago

Apr 20, 2011

(PhysOrg.com) -- Galaxies are thought to develop by the gravitational attraction between and merger of smaller 'sub-galaxies', a process that standard cosmological ideas suggest should be ongoing. But new ...

NGC 4696: A cosmic question mark

Aug 12, 2010

This picture, taken by Hubble's Advanced Camera for Surveys, is not just a beautiful snapshot of NGC 4696, the largest galaxy in the Centaurus Cluster (galaxy cluster Abell 3526). It is also an illustration ...

Stars forced to relocate near the Southern Fish

Mar 03, 2009

About 100 million light-years away, in the constellation of Piscis Austrinus (the Southern Fish), three galaxies are playing a game of gravitational give-and-take that might ultimately lead to their merger ...

3D galaxies -- coming straight on for you

Jun 29, 2011

As we've recently learned, the ATLAS3D project was able to study 260 individual galaxies and do some very amazing things. By imaging in both red and blue shift, astronomers were able to take stellar measurements and give ...

Recommended for you

Lives and deaths of sibling stars

6 hours ago

This beautiful star cluster, NGC 3293, is found 8000 light-years from Earth in the constellation of Carina (The Keel). This cluster was first spotted by the French astronomer Nicolas-Louis de Lacaille in ...

Fermi finds a 'transformer' pulsar

23 hours ago

(Phys.org) —In late June 2013, an exceptional binary containing a rapidly spinning neutron star underwent a dramatic change in behavior never before observed. The pulsar's radio beacon vanished, while at ...

User comments : 14

Adjust slider to filter visible comments by rank

Display comments: newest first

Peteri
5 / 5 (7) Jul 21, 2011
Interesting article. And Kevinrts, before you make your standard ignorance-based comments about how this all goes to prove that cosmology has got it all wrong and that your deity created the current universe in just a few days, this is how science works - unlike religious dogmas, scientific theories get revised in the light of new evidence.
jsdarkdestruction
5 / 5 (3) Jul 21, 2011
I wonder what crank will show up first claiming this is proof that everything we think we know about the universe is wrong and its time to throw it all away and start over.....
Most likely by looking at their pet models which the mainstream "ignores" and even "conspires against."
Argon
1 / 5 (1) Jul 21, 2011
@Peteri
and
@isdarkdestruction

I like your sense of anticipation, resting upon your expectations: stand by!
yyz
5 / 5 (3) Jul 21, 2011
"...the formation of the two studied elliptical galaxies (NGC 680 & NGC 5557) originated from a merger of two giant spiral galaxies that took place only 1 to 3 billions years ago."

That a recent merger episode occurred in these two galaxies had already been established -

NGC 680: http://iopscience....web.pdf

NGC 5557: http://www.aanda.....519MFUL

One of the questions asked is whether these two galaxies are representative of the other 260 nearby ETGs in the ATLAS sample. Too early too tell, I'd say.

In addition, the characterization of Tidal Dwarf Galaxies surrounding NGC 5557 and faint tidal debris around NGC 680 really shows off the merits of these new, deep, CFHT images. Looking forward to the completion of the survey and what surprises it may uncover in the ATLAS sample.
LKD
5 / 5 (1) Jul 21, 2011
The first thing I think of in regards to this is what different environment is the elliptical within now that the original spirals did not have? I believe this will lead to a better understanding of the physics behind spiral arms in galaxies.
RobertKarlStonjek
1 / 5 (1) Jul 22, 2011
I wonder what crank will show up first claiming

People at this address think that the Big Bang and all that it implies (superluminal recession speeds etc) is wonderful.
http://www.facebo...267?ap=1
FrankHerbert
1 / 5 (7) Jul 23, 2011
I wonder what crank will show up first claiming

People at this address think that the Big Bang and all that it implies (superluminal recession speeds etc) is wonderful.
http://www.facebo...267?ap=1


Ding ding ding ding ding! We have a winner!
frajo
not rated yet Jul 23, 2011
Ding ding ding ding ding! We have a winner!

There's an interesting coherence between you and jsdarkdestruction.
vidyunmaya
1 / 5 (2) Jul 23, 2011
Sub: Awaken -Onset modes
This becomes a transit zone from Source-fields,Flows,Reflectors and Protective region to Prime Functional -Cosmological Index
vidyardhicosmology[dot]blogspot[dot]com
Vidyardhi Nanduri
ArkavianX
not rated yet Jul 24, 2011
This would make sense if galaxies are credited as sort of a gravitational capacitor or sinkhole. The smaller galaxy that gets too close discharges most of it to the bigger galaxy and some continues flying by. This after 'lost' debris then re-coalesces into the typical elliptical and/or globular clusters.
Tuxford
1 / 5 (3) Jul 26, 2011
Photos appear to show expanding superwave shells of matter ejected from the galactic cores. Note how in each case the shells are centered on the galactic centers. This explanation is simpler than trying to assert that each is a result of some complex merger that resulted in such concentric symmetry centered on the core. Should one not at least consider the simpler explanation???
Callippo
not rated yet Jul 26, 2011
The fact, galaxy appears elliptical means, the tidal forces wiped out all irregularities in the motion of its stars. It's similar to situation, when young planet would revolve the parent star along circular path. This process indeed requires a lotta time. So we should find some mechanism, how the galaxy would get its regular shape faster, or how the stellar streams could survive longer.

I'm somehow inclined to the later option. For example, we could imagine, the stellar stream coincides with invisible dark matter stream, which stabilizes and freezes the stars in it like fiber of invisible slime.
jsdarkdestruction
5 / 5 (1) Jul 28, 2011
No oliver? I was sure this proved neutron repulsion (and probably climate change and it being a conspiracy) somehow.....
I see nothing compelling in the theory you keep preaching tuxford, nice try though.
pauldentler
not rated yet Aug 07, 2011
I wonder what crank will show up first claiming this is proof that everything we think we know about the universe is wrong and its time to throw it all away and start over.....
Most likely by looking at their pet models which the mainstream "ignores" and even "conspires against."


OK, I'll bite. How about a postulate that goes like this: "So far as we can observe, everything in the Universe orbits something else, including the largest galaxies.