This would run counter to the widely-held belief that massive, luminous galaxies (like our own Milky Way Galaxy) began their formation and evolution shortly after the Big Bang, some 13 billion years ago. Further research into the nature of these objects could open new windows into the study of the origin and early evolution of galaxies.
John Salzer, principal investigator for the study published today in Astrophysical Journal Letters, said that the 15 galaxies in the sample exhibit luminosities (a measure of their total light output) that indicate that they are massive systems like the Milky Way and other so-called “giant” galaxies. However, these particular galaxies are unusual because they have chemical abundances that suggest that very little stellar evolution has taken place within them. Their relatively low abundances of “heavy” elements (elements heavier than helium, called “metals” by astronomers) imply that the galaxies are cosmologically young and may have formed recently.
The chemical abundances of the galaxies, combined with some simple assumptions about how stellar evolution and chemical enrichment progress in galaxies in general, suggest that they may only be 3 or 4 billion years old, and therefore formed 9 to 10 billion years after the Big Bang. Most theories of galaxy formation predict that massive, luminous systems like these should have formed much earlier.
If this overall interpretation proves correct, the galaxies may allow astronomers to investigate phases of the galaxy formation and evolution process that have been difficult to study because they normally occur at such early times in the Universe, and therefore at very large distances from us.
“These objects may represent a unique window on the process of galaxy formation, allowing us to study relatively nearby systems that are undergoing a phase in their evolution that is analogous to the types of events that, for most galaxies, typically occurred much earlier in the history of the Universe," Salzer said.The discoveries are the result of a multi-year survey of more than 2,400 star-forming galaxies called the Kitt Peak National Observatory International Spectroscopic Survey (KISS). The survey was designed to collect basic observational data for a large number of extragalactic emission-line sources. Additional rounds of follow-up spectroscopy for the sources discovered in the initial survey led to the discovery of the 15 luminous, low-abundance systems.
"The reason we found these types of galaxies has to do with the unique properties of the KISS survey method," Salzer said. "Galaxies were selected via their strong emission lines, which is the only way to detect these specific galaxies." Previous surveys done by others have largely missed findings these unusual galaxies.
While the hypothesis that these galaxies are cosmologically young is provocative, it is not the only possible explanation for these enigmatic systems. An alternative explanation proposes that the galaxies are the result of a recent merger between two smaller galaxies. Such a model might explain these objects, since the two-fold result of such a merger might be the reduction of metal abundances due to dilution from unprocessed gas and a brief but large increase in luminosity caused by rampant star formation. As a way to distinguish between these two scenarios, Salzer and his team intend to request observing time on NASA's Hubble Space Telescope to use high-resolution imaging to determine whether or not the systems might be products of merging.
A National Science Foundation Presidential Faculty Award to Salzer, as well as continued NSF support cumulatively totaling $1.2 million, funded the KISS survey and supporting work.
Also contributing to the Astrophysical Journal Letters paper were astronomers Anna Williams of Wesleyan University in Middletown, Conn. and Caryl Gronwall of Pennsylvania State University. Salzer is at IU while on leave from his position of professor of astronomy at Wesleyan, but expects to formally join the faculty at IU in the coming year. The authors also recognized KISS team members Gary Wegner, Drew Phillips, Jessica Werk, Laura Chomiuk, Kerrie McKinstry, Robin Ciardullo, Jeffrey Van Duyne and Vicki Sarajedini for their participation in the follow-up spectroscopic observations over the past several years.
To speak with Salzer, please contact Steve Chaplin, Indiana University Office of Communications, at 812-856-1896, or email@example.com.
Steve Chaplin | Newswise Science News
Further reports about: > Big Bang > Galaxy > Galaxy Formation Theories > Helium > KISS > Milky Way > Universe > emission lines > extragalactic emission-line sources > galaxy formation > luminosities > luminous galaxies > luminous systems > massive galaxies > milky way galaxy > smaller galaxies > stellar evolution
Physicists discover that lithium oxide on tokamak walls can improve plasma performance
22.05.2017 | DOE/Princeton Plasma Physics Laboratory
Experts explain origins of topographic relief on Earth, Mars and Titan
22.05.2017 | City College of New York
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.
Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...
22.05.2017 | Event News
17.05.2017 | Event News
16.05.2017 | Event News
22.05.2017 | Materials Sciences
22.05.2017 | Life Sciences
22.05.2017 | Physics and Astronomy