Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Watching a tiny galaxy grow

09.02.2012
For the first time, astronomers have caught a so-called dwarf galaxy in the process of swallowing another, even smaller galaxy.
Whether such mergers are important in the formation of the tiniest galaxies has been the subject of debate among theoreticians. Now, thanks to research by two independent groups including MPIA researchers David Martínez-Delgado and Michelle Collins, there is empirical evidence that such mergers occur. The analyses draw on deep images from modestly sized telescopes, in an example for successful collaboration between amateur and professional astronomers.

In the widely accepted hierarchical model of galaxy evolution, much of galactic growth involves acts of cannibalism and large-scale mergers: pre-existing, smaller galaxies successively coalesce into larger pieces until large galaxies, the size of the Milky Way or even bigger, form. But before galaxies and their stars can merge, stars have to form in the first place.

This is thought to happen by gas gathering to form denser regions under the influence of its own gravity; once a critical density is reached, stars are born. Conceivably, the smallest galaxies, so-called dwarf galaxies, might form in this way directly, and might grow bigger as they incorporate new gas from their surroundings, processing the new material into stars. In this way, there would be growth without the need for mergers. And indeed, until now, no such mergers had been observed.

Now, two independent groups of researchers, one led by David Martínez-Delgado of the Max Planck Institute for Astronomy (MPIA), the other by Michael Rich of UCLA, have identified the first confirmed example for a galaxy merger between very small galaxies. They found convincing evidence that a small companion of the dwarf galaxy NGC 4449 in the constellation Canis Venatici, first identified in 2007, is indeed another, smaller dwarf galaxy in the process of being disrupted by its larger neighbour – prior to being swallowed up.

Martínez-Delgado says: "A number of models predict that dwarfs should eat dwarfs. But this is the first clear example of such a feast that has been actually observed: We've found a key piece of the puzzle of galaxy evolution. Also, the fact that NGC 4449 is quite close to us shows that processes like this are still happening. They need to be taken into account if we want to describe our cosmic neighbourhood."

MPIA's Michelle Collins, who worked with Michael Rich on analyzing the dwarf galaxy's shape, adds: "Knowing what a half-digested dwarf galaxy looks like should help us find additional examples of dwarfs eating dwarfs. Finding a fair number of examples should put our models of the first stages of galactic growth on a firm footing – or show what we're missing."

Mass estimates for the distorted dwarf suggest that it contains significant amounts of Dark Matter, which does not emit light and only interacts with ordinary, atomic matter via gravity. If so, then this pairing could be a rare glimpse of a "stealth merger" – a galaxy's merger with a low-brightness object that is difficult to observe directly, yet, due to its high mass, can have a major influence on the receiving galaxy's shape, size and dynamics.

Both groups' examinations of the smaller dwarf galaxy's basic properties was performed with modest-scale instruments in cooperation with amateur astronomers: Rich et al. used the Saturn Lodge 0.7m telescope on the grounds of the Polaris Observatory Association for observations May-June 2011, while Martínez-Delgado et al. used Jay GaBany's 0.5 m telescope at Black Bird Observatory for observations between April 2010 and January 2011. Martínez-Delgado et al. followed up with detailed observations using the SUBARU telescope on Hawai'i in January 2011, obtaining images in which the smaller galaxy's haze is resolved into separate stars.

The paper by Rich et al. will appear in the February 9, 2012 issue of the journal Nature. The paper by Martínez-Delgado et al. is in press at the Astrophysical Journal Letters.

Contact

David Martínez-Delgado (Science contact)
Max Planck Institute for Astronomy
Phone: (+49|0) 6221 – 528 455
Email: delgado@mpia.de

Michelle Collins (Science contact)
Max Planck Institute for Astronomy
Phone: (+49|0) 6221 – 528 360
Email: collins@mpia.de

Markus Pössel (Public relations)
Max Planck Institute for Astronomy
Phone: (+49|0) 6221 – 528 261
Email: pr@mpia.de

Dr. Markus Pössel | Max-Planck-Institut
Further information:
http://www.mpia.de

More articles from Physics and Astronomy:

nachricht NASA spacecraft investigate clues in radiation belts
28.03.2017 | NASA/Goddard Space Flight Center

nachricht Researchers create artificial materials atom-by-atom
28.03.2017 | Aalto University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Transport of molecular motors into cilia

28.03.2017 | Life Sciences

A novel hybrid UAV that may change the way people operate drones

28.03.2017 | Information Technology

NASA spacecraft investigate clues in radiation belts

28.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>