Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Massive galaxies formed when universe was young

25.11.2010
New findings disagree with current models

Some of the universe's most massive galaxies may have formed billions of years earlier than current scientific models predict, according to surprising new research led by Tufts University. The findings appear in the Astrophysical Journal published online Nov. 24 in advance of print publication on Dec. 10, 2010.

"We have found a relatively large number of very massive, highly luminous galaxies that existed almost 12 billion years ago when the universe was still very young, about 1.5 billion years old. These results appear to disagree with the latest predictions from models of galaxy formation and evolution," said Tufts astrophysicist Danilo Marchesini, lead author on the paper and assistant professor of physics and astronomy at the Tufts School of Arts and Sciences. "Current understanding of the physical processes responsible in forming such massive galaxies has difficulty reproducing these observations."

Collaborating with Marchesini were researchers from Yale University, Carnegie Observatories, Leiden University, Princeton University, the University of Kansas and the University of California-Santa Cruz.

The newly identified galaxies were five to ten times more massive than our own Milky Way. They were among a sample studied at redshift 3¡Üz

Redshift refers to the phenomenon of a light wave stretching and moving toward longer wavelengths (the red end of the spectrum) as the emitting object travels away from an observer (Doppler Effect). This is similar to the pitch of a siren getting lower as the siren moves away. The redshift of distant galaxies is due to the expansion of the universe. The larger the redshift, the more distant the galaxy is, or the farther back in time we are observing. The larger the redshift, the younger the universe in which the galaxy is observed.

By complementing existing data with deep images obtained through a new system of five customized near-infrared filters, the researchers were able to get a more complete view of the galaxy population at this early stage and more accurately characterize the sampled galaxies.

Massive Galaxies Ferociously Active

The researchers made another surprising discovery: More than 80 percent of these massive galaxies show very high infrared luminosities, which indicate that these galaxies are extremely active and most likely in a phase of intense growth. Massive galaxies in the local universe are instead quiescent and do not form stars at all.

The researchers note that there are two likely causes of such luminosity: New stars may be forming in dust-enshrouded bursts at rates of a few thousand solar masses per year. This would be tens to several hundreds of times greater than the rates estimated by spectral energy distribution (SED) modeling. Alternatively, the high infrared luminosity could be due to highly-obscured active galactic nuclei (AGN) ferociously accreting matter onto rapidly growing super-massive black holes at the galaxies' centers.

There might be an explanation that would at least partially reconcile observations with model-predicted densities. The redshifts of these massive galaxies, and hence their distances, were determined from the SED modeling and have not yet been confirmed spectroscopically. Redshift measurements from SED modeling are inherently less accurate than spectroscopy. Such "systemic uncertainties" in the determination of the distances of these galaxies might still allow for approximate agreement between observations and model predictions.

If half of the massive galaxies are assumed to be slightly closer, at redshift z=2.6, when the universe was a bit older (2.5 billion years old) and very dusty (with dust absorbing much of the light emitted at ultra-violet and optical wavelengths), then the disagreement between observations and model predictions becomes only marginally significant.

However, the discovery of the existence of such massive, old and very dusty galaxies at redshift z=2.6 would itself be a notable discovery. Such a galaxy population has never before been observed.

"Either way, it is clear that our understanding of how massive galaxies form is still far from satisfactory," said Marchesini.

"The existence of these galaxies so early in the history of the universe, as well as their properties, can provide very important clues on how galaxies formed and evolved shortly after the Big Bang," he added.

The National Science Foundation provided support for the research.

"The Most Massive Galaxies at 3.0 ¡ÜZ
Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville, and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoys a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of innovative teaching and research initiatives span all Tufts campuses, and collaboration among the faculty and students in the undergraduate, graduate, and professional programs across the university's schools is widely encouraged.

Kim Thurler | EurekAlert!
Further information:
http://www.tufts.edu

More articles from Physics and Astronomy:

nachricht MSU astronomers discovered supermassive black hole in an ultracompact dwarf galaxy
14.08.2018 | Lomonosov Moscow State University

nachricht ASU astrophysicist helps discover that ultrahot planets have starlike atmospheres
13.08.2018 | Arizona State 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: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>