NASA Rocket Redefines What Astronomers Think of as Galaxies
 
Nov 6, 2014: A NASA sounding rocket experiment has detected a surprising
surplus of infrared light in the dark space between galaxies, a diffuse cosmic
glow as bright as all known galaxies combined. The glow is thought to be from
orphaned stars flung out of galaxies.
 
The findings redefine what scientists think of as galaxies. Galaxies may not
have a set boundary of stars, but instead stretch out to great distances,
forming a vast, interconnected sea of stars.
 
http://www.jpl.nasa.gov/spaceimages/details.php?id=pia18853
 
This is a time-lapse photograph of the Cosmic Infrared Background Experiment
(CIBER) rocket launch, taken from NASA's Wallops Flight Facility in Virginia
in 2013. The image is from the last of four launches. Image Credit: T.
Arai/University of Tokyo
 
Observations from the Cosmic Infrared Background Experiment, or CIBER, are
helping settle a debate on whether this background infrared light in the
universe, previously detected by NASA's Spitzer Space Telescope, comes from
these streams of stripped stars too distant to be seen individually, or
alternatively from the first galaxies to form in the universe.
 
"We think stars are being scattered out into space during galaxy collisions,"
said Michael Zemcov, lead author of a new paper describing the results from
the rocket project and an astronomer at the California Institute of Technology
(Caltech) and NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
"While we have previously observed cases where stars are flung from galaxies
in a tidal stream, our new measurement implies this process is widespread."
 
Using suborbital sounding rockets, which are smaller than those that carry
satellites to space and are ideal for short experiments, CIBER captured
wide-field pictures of the cosmic infrared background at two infrared
wavelengths shorter than those seen by Spitzer. Because our atmosphere itself
glows brightly at these particular wavelengths of light, the measurements can
only be done from space.
 
"It is wonderfully exciting for such a small NASA rocket to make such a huge
discovery," said Mike Garcia, program scientist from NASA Headquarters.
"Sounding rockets are an important element in our balanced toolbox of missions
from small to large."
 
http://www.jpl.nasa.gov/spaceimages/details.php?id=pia18855
 
CIBER measurements favor a model in which the IR glow between distant galaxies
is caused by orphan stars. MoreDuring the CIBER flights, the cameras launch
into space, then snap pictures for about seven minutes before transmitting the
data back to Earth. Scientists masked out bright stars and galaxies from the
pictures and carefully ruled out any light coming from more local sources,
such as our own Milky Way galaxy. What's left is a map showing fluctuations in
the remaining infrared background light, with splotches that are much bigger
than individual galaxies. The brightness of these fluctuations allows
scientists to measure the total amount of background light.
 
To the surprise of the CIBER team, the maps revealed a dramatic excess of
light beyond what comes from the galaxies.  The data showed that this infrared
background light has a blue spectrum, which means it increases in brightness
at shorter wavelengths. This is evidence the light comes from a previously
undetected population of stars between galaxies. Light from the first galaxies
would give a spectrum of colors that is redder than what was seen.
 
"The light looks too bright and too blue to be coming from the first
generation of galaxies," said James Bock, principal investigator of the CIBER
project from Caltech and JPL. "The simplest explanation, which best explains
the measurements, is that many stars have been ripped from their galactic
birthplace, and that the stripped stars emit on average about as much light as
the galaxies themselves."
 
Future experiments can test whether stray stars are indeed the source of the
infrared cosmic glow. If the stars were tossed out from their parent galaxies,
they should still be located in the same vicinity. The CIBER team is working
on better measurements using more infrared colors to learn how stripping of
stars happened over cosmic history.
 
Results from two of four CIBER flights, both of which launched from White
Sands Missile Range in New Mexico in 2010 and 2012, appear Friday, Nov. 7 in
the journal Science.
 
Credits:
Production editor: Dr. Tony Phillips | Credit: Science@NASA
 
More information:
 
For more information on NASA's sounding rocket experiments, visit:
http://www.nasa.gov/mission_pages/sounding-rockets/
 
For more information about CIBER, visit: http://ciber.caltech.edu/rocket.html
 
Caltech manages JPL for NASA. The work was supported by NASA, with initial
support provided by JPL's Director's Research and Development Fund. Japanese
participation in CIBER was supported by the Japan Society for the Promotion of
Science and the Ministry of Education, Culture, Sports, Science and
Technology. Korean participation in CIBER was supported by the Korean
Astronomy and Space Science Institute."
 
 
Regards,
 
Roger

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