Using the powerful one-two combo of NASA’s Swift satellite and the Gemini Observatory, astronomers from a number of institutions, including Johns Hopkins, have detected a mysterious type of cosmic explosion farther back in time than ever before.
The explosion, known as a short gamma-ray burst (GRB), took place 7.4 billion years ago, more than halfway back to the Big Bang.
"This discovery dramatically moves back the time at which we know short GRBs were exploding. The short burst is almost twice as far as the previous confirmed record holder," says John Graham, a graduate student in the Henry A. Rowland Department of Physics and Astronomy at The Johns Hopkins University. Graham is presenting his group’s discovery at the American Astronomical Society’s 2008 winter meeting this week in Austin, Texas.
GRBs are among the most powerful explosions in the universe, releasing enormous amounts of energy in the form of X-rays and gamma rays. Most bursts fall in one of two categories: long bursts and short bursts, depending on whether they last more or less than three seconds. Astronomers believe that long GRBs are triggered by the collapse and explosion of massive stars. In contrast, a variety of mechanisms has been proposed for short bursts. The most popular model says that most short GRBs occur when two neutron stars smash into each other and collapse into a black hole, ejecting energy in two counter-flowing beams.
The record-setting short burst is known as GRB 070714B, named because it was the second GRB detected on July 14, 2007. NASA’s Swift Gamma-Ray Burst Mission discovered the GRB in the constellation Taurus. Rapid follow-up observations with the 2-meter Liverpool Telescope and the 4-meter William Herschel Telescope found an optical afterglow in the same location as the burst, which allowed astronomers to identify the GRB’s host galaxy.
Next, Graham and his colleagues, Andrew Fruchter of the Space Telescope Science Institute and Andrew Levan of the University of Warwick in the United Kingdon, trained the 8-meter Gemini North Telescope in Hawaii on the galaxy. Analysis of a spectrum of the light from that galaxy indicated that it is 7.4 billion light-years away, meaning the explosion occurred 7.4 billion years ago.
"The fact that this short burst is so far away means this subclass has a broad range of distances, although they still tend to be closer on average than long GRBs," says Swift lead scientist Neil Gehrels of NASA’s Goddard Space Flight Center in Greenbelt, Md.
Gehrels adds that GRB 070714B’s energy was about 100 times higher than average for short bursts, more similar to the typical energy of a long GRB.
"It is unclear whether another mechanism is needed to explain this explosion, such as a neutron star-black hole merger," Gehrels said. "Or it could be that there are a wide range of energies for neutron star-neutron star mergers, but that seems unlikely."
Another possibility is that GRB 070714B concentrated its energy in two very narrow beams and that one of the beams happened to be aimed directly at Earth, making the burst seem more powerful than it really was. Researchers wonder if most short GRBs eject their energy in wider, less concentrated beams.
"We now have a good idea of the type of star that produces the brighter long bursts. But how short bursts are formed remains a mystery," Fruchter said.
Lisa DeNike | EurekAlert!
Smallest transistor worldwide switches current with a single atom in solid electrolyte
17.08.2018 | Karlsruher Institut für Technologie (KIT)
Protecting the power grid: Advanced plasma switch for more efficient transmission
17.08.2018 | DOE/Princeton Plasma Physics Laboratory
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
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...
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....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
20.08.2018 | Information Technology
20.08.2018 | Life Sciences
20.08.2018 | Information Technology