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{at}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

--- D'Bridge 3.99