Fermi Detects Light From Earliest Stars In Universe

By  //  June 8, 2014

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Stunning New Discovery Astounds Astronomers

ABOVE VIDEO: Three hundred and fifty miles overhead, the Fermi Gamma-ray Space Telescope silently glides through space. From this serene vantage point, the satellite’s instruments watch the fiercest processes in the universe unfold. Pulsars spin up to 700 times a second, sweeping powerful beams of gamma-ray light through the cosmos. The hyperactive cores of distant galaxies spew bright jets of plasma. Far beyond, something mysterious explodes with unfathomable power, sending energy waves crashing through the universe.

BREVARD COUNTY • KENNEDY SPACE CENTER, FLORIDA – NASA astronomers have detected what they believe is shadows of light emanating from the very first stars of the universe.

Ultraviolet and other light emitted by all the stars that ever existed is still visible throughout the universe. Astronomers refer to this starlight as the extragalactic background light or EBL. (Image courtesy NASA/JPL/Fermi)

Astronomers have revealed that some the light they have detected may be as old as the start of time.

The new discovery about the early universe was discovered using the Fermi Gamma-ray Space Telescope.

Fermi was launched into orbit in June 2008 from Cape Canaveral Air Force Station aboard a Delta II 7920-H Rocket.

Astronomers say soon after Big Band more than 13.7 years ago, the universe cooled enough to let atoms form, which eventually clumped together to create the first stars. The stars grew and spread and since then their light has filled the universe.

This NASA image shows the locations of 150 blazars (green dots) used in the EBL study of the earliest formed stars in the universe. (Image courtesy of NASA/JPL/Fermi)

EXTRAGLACTIC BACKGROUND LIGHT GLOW

Fermi’s discovery has detected the glow of the first stars, called extragalactic background light, or EBL and using a complex formula has filtered out light from newer stars, isolating the light from the early universe.

“The EBL is the ensemble of photons generated by all the stars and also all the black holes in the universe,” said Marco Ajello of the SLAC National Accelerator Laboratory in California, an astrophysicist who led the research.

“The EBL also includes the light of the first massive stars that ever shone. We have a fairly good knowledge of the light emitted by ‘normal’ stars. Thus, by measuring the EBL we are able to constrain the light of the first stars.”

“The EBL also includes the light of the first massive stars that ever shone. We have a fairly good knowledge of the light emitted by ‘normal’ stars. Thus, by measuring the EBL we are able to constrain the light of the first stars.”

Ajello said the Fermi spacecraft and its telescopes studied light from objects called blazars, which are giant black holes that release copious amounts of light while gobbling up large meals of matter.

Marco Ajello

Marco Ajello

“We use blazars as cosmic lighthouses,” Ajello said.

“We observe their dimming due to the EBL ‘fog’. This allows us to quantify how much EBL there is between us and the blazars. As blazars are distributed across the universe, we can measure the EBL at different epochs.”

The very first stars are believed to differ significantly from many stars that form today, according to Ajello. They were huge celestial objects, hundreds of sizes greater than our own sun and these stars burned more intensely and emitted more light.

Ajello said the new discovery will assist astronomers to learn how quickly after the Big Bang that stars were formed.

The Fermi spacecraft and observatory was launched into orbit in June 2008 from Cape Canaveral Air Force Station aboard a Delta II 7920-H Rocket. (Image courtesy NASA/JPL/Fermi)

FERMI MARKS FIRST STEP INTO THIS COSMIC FRONTIER

“With Fermi we have the first step into this cosmic frontier,” said Volker Bromm, a University of Texas astronomer at a NASA press conference.

The Fermi observatory performs gamma-ray astronomy from its low Earth orbit and also studies cosmic phenomena such as pulsars, dark matter, high-energy sources, gamma-ray bursts and quasars.

VIEWING LIGHT FROM ANCIENT GALAXIES

Employing an enormous field of view, Fermi’s Large Area telescope can screen more than 20 percent of the sky at a time and covers the entire sky every three hours. It can be pointed at specific targets and is more than 30 times more sensitive than any other gamma-ray instrument previously deployed in space.

The James Webb Space Telescope, while nearing completion, is facing cancellation by Congress. (NASA image)

The James Webb Space Telescope, while nearing completion, is facing cancellation by Congress. (NASA image)

Bromm said NASA researchers will study all the data provided by Fermi and hopefully be able to actually view light from ancient galaxies, using new high-tech telescopes such as the James Webb Space Telescope, NASA’s follow-up to the Hubble Space Telescope.

The new James Webb Space Telescope is expected to be launched in 2018.

“Detecting these stars is very important, but currently impossible,” Ajello said.

“The Webb Telescope in a few years might be able to see the first galaxies, not the first stars though. In this way we are already able to set constraints on the amount and role of these stars in the early universe.”


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