"This observation required a rare and exceptionally bright event to allow us to probe the fragile environment where stars were forming just 3 billion years after the Big Bang. After correcting for the extreme dust extinction, this is intrinsically the second brightest GRB afterglow to date; it would have been easily observed with amateur telescopes, if not for the dust in the way," said Jason X. Prochaska, professor of astronomy and astrophysics at the University of California, Santa Cruz.
Prochaska's team will present its findings at the American Astronomical Society meeting this week in Long Beach, Calif. A paper describing the results has been accepted for publication in Astrophysical Journal Letters.
Stars form in vast clouds of molecular gas and dust, and astronomers have expected to find evidence of these molecular clouds in GRB host galaxies. Until now, however, efforts to detect molecular gas in GRB afterglow spectra had been unsuccessful. The new observations by Prochaska and his coauthors indicate that star formation in the early universe occurred in environments similar to star-forming regions in the Milky Way.
The study focused on a "long duration" gamma-ray burst known as GRB 080607. This type of burst is thought to occur when a massive star collapses to form a black hole. The initial burst of high-energy gamma rays was followed by a slowly fading afterglow of radiation over the entire spectrum of wavelengths.
"We suspect that previous events like 080607 were too faint to be observed on Earth," said coauthor Yaron Sheffer of the University of Toledo. "Many so-called dark bursts, with no observable afterglow, probably mark the dusty, highly extinguished environments of young star-forming regions."
NASA's Swift satellite detected the gamma-ray burst and began x-ray observations, while alerting astronomers and triggering automatic observations by ground-based telescopes such as the Katzman Automatic Imaging Telescope at Lick Observatory. Team members Joshua Bloom, Daniel Perley, and Adam Miller of UC Berkeley happened to be using the Keck I Telescope at the W. M. Keck Observatory in Hawaii and began spectroscopic observations within 15 minutes using the Low Resolution Imaging Spectrograph (LRIS).
The resulting spectrum of the optical afterglow yielded information about the dust, gas, and metals in the interstellar medium through which the light passed on its way out of the host galaxy. In addition to the first clear detection of molecular gases (both carbon monoxide and hydrogen), the spectrum indicated a metal composition comparable to that of the Sun (to astronomers, "metals" are elements heavier than hydrogen and helium).
The spectrum also has many features researchers have never seen before, Prochaska said. In addition to hundreds of standard absorption lines corresponding to known transitions of various elements, the spectrum shows many absorption lines that researchers have yet to identify.
"This is easily the most fascinating spectrum that I've ever worked on," Prochaska said. "Nearly half of the features remain a mystery, and it is possible that no one has ever detected them previously, either in controlled laboratory experiments or in spectra from our galaxy or other galaxies."
There is also more hydrogen in this spectrum than along any path through the Milky Way, he added. "This remains a bit of a puzzle," Prochaska said. "For now, we don't know much about the galaxy that hosted the explosion, but the evidence suggests it has been prodigious in terms of star formation."
The burst and its afterglow were observed in June, and the team did not manage to get images of the host galaxy before it moved to a position in the sky where it could not be observed. In January, the researchers will image the galaxy to connect their findings on the star-forming region with its global properties.
Tim Stephens | EurekAlert!
APEX takes a glimpse into the heart of darkness
25.05.2018 | Max-Planck-Institut für Radioastronomie
First chip-scale broadband optical system that can sense molecules in the mid-IR
24.05.2018 | Columbia University School of Engineering and Applied Science
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences