Artist's View of a Dense Galaxy Core Forming
This illustration reveals the celestial fireworks deep inside the
crowded core of a developing galaxy, as seen from a hypothetical
planetary system. The sky is ablaze with the glow from nebulae,
fledgling star clusters, and stars exploding as supernovae. The rapidly
forming core may eventually become the heart of a mammoth galaxy
similar to one of the giant elliptical galaxies seen today.
Science Credit: NASA, ESA, E. Nelson and P. van Dokkum (Yale University), M. Franx (Leiden Observatory), G. Brammer (STScI),
I. Momcheva (Yale University), N. Schreiber (Max Planck Institute for
Extraterrestrial Physics), E. da Cunha (Max Planck Institute for
Astronomy), L. Tacconi (Max Planck Institute for Extraterrestrial
Physics), R. Bezanson (Steward Observatory/University of Arizona), A.
Kirkpatrick (University of Massachusetts), J. Leja (Yale University),
H.-W. Rix (Max Planck Institute for Astronomy), R. Skelton (South
African Astronomical Observatory), A. van der Wel (Max Planck Institute
for Astronomy), K. Whitaker (Goddard Space Flight Center), and S.
Wuyts (Max Planck Institute for Extraterrestrial Physics). Release Images
Distant Galaxy in GOODS-North (GOODS-N -77)
The core of an emerging galaxy is ablaze with newly formed stars in
this never-before-seen view of the early construction phase of an
elliptical galaxy. Astronomers spotted the glowing core in this Hubble
Space Telescope image from the Great Observatories Origins Deep Survey
(GOODS). The arrow in the enlarged inset image points to the growing
galaxy's bright, compact core. The galaxy is seen as it appeared 11
billion years ago, just 3 billion years after the Big Bang.
Although only a fraction of the size of the Milky Way, the tiny
powerhouse galaxy already contains about twice as many stars as our
galaxy, all crammed into a region only 6,000 light-years across. The
Milky Way is about 100,000 light-years across. Astronomers think the
newly formed galaxy will continue to grow, possibly becoming similar to
the giant elliptical galaxies seen today. This barely visible galaxy
may be representative of a much larger population of similar objects
that are obscured by dust.
Astronomers have for the first time gotten a glimpse of the earliest stages of massive galaxy construction. The building site, dubbed "Sparky," is a developing galaxy containing a dense core that is blazing with the light of millions of newborn stars which are forming at a ferocious rate. The discovery was made possible through combining observations from NASA's Hubble and Spitzer space telescopes, the European Space Agency's Herschel Space Observatory, and the W.M. Keck Observatory in Hawaii.
The image combines observations taken in near-infrared light with the
Wide Field Camera 3 and exposures made in visible light with the
Advanced Camera for Surveys. Credit: NASA, ESA, and G. Illingworth (University of California, Santa Cruz), and the GOODS teamT
Astronomers have for the first time gotten a glimpse of the earliest stages of massive galaxy construction. The building site, dubbed "Sparky," is a developing galaxy containing a dense core that is blazing with the light of millions of newborn stars which are forming at a ferocious rate. The discovery was made possible through combining observations from NASA's Hubble and Spitzer space telescopes, the European Space Agency's Herschel Space Observatory, and the W.M. Keck Observatory in Hawaii.
Because the infant galaxy is so far away, it is seen as it appeared
11 billion years ago, just 3 billion years after the birth of the
universe in the big bang. Astronomers think the compact galaxy will
continue to grow, possibly becoming a giant elliptical galaxy, a
gas-deficient assemblage of ancient stars theorized to develop from the
inside out, with a compact core marking its beginnings.
"We really hadn't seen a formation process that could create things
that are this dense," explained Erica Nelson of Yale University in New
Haven, Connecticut, lead author of the science paper announcing the
results. "We suspect that this core-formation process is a phenomenon
unique to the early universe because the early universe, as a whole,
was more compact. Today, the universe is so diffuse that it cannot
create such objects anymore."
The research team's paper appears in the August 27 issue of the journal Nature.
Although only a fraction of the size of the Milky Way, the tiny
powerhouse galaxy already contains about twice as many stars as our
galaxy, all crammed into a region only 6,000 light-years across. The
Milky Way is about 100,000 light-years across. This barely visible
galaxy may be representative of a much larger population of similar
objects that are obscured by dust.
"They're very extreme environments," Nelson said. "It's like a
medieval cauldron forging stars. There's a lot of turbulence, and it's
bubbling. If you were in there, the night sky would be bright with
young stars, and there would be a lot of dust, gas, and remnants of
exploding stars. To actually see this happening is fascinating."
Alongside determining the galaxy's size from the Hubble images, the
team dug into archival far-infrared images from the Spitzer and
Herschel telescopes. The analysis allowed them to see how fast the
young galaxy is churning out stars. Sparky is producing roughly 300
stars per year. By comparison, the Milky Way produces roughly 10 stars
per year.
Astronomers believe that this frenzied star formation occurred
because the galactic center is forming deep inside a gravitational well
of dark matter, an invisible form of matter that makes up the
scaffolding upon which galaxies formed in the early universe. A torrent
of gas is flowing into this well at the galaxy's core, sparking waves
of star birth.
The sheer amount of gas and dust within an extreme star-forming
region like this may explain why these compact galaxies have eluded
astronomers until now. Bursts of star formation create dust, which
builds up within the forming galaxy and can block some starlight.
Sparky was only barely visible, and it required the infrared
capabilities of Hubble's Wide Field Camera 3, Spitzer, and Herschel to
reveal the developing galaxy.
The observations indicate that the galaxy had been furiously making
stars for more than a billion years (at the time the light we now
observe began its long journey). But the galaxy didn't keep up this
frenetic pace for very long, the researchers suggested. Eventually, the
galaxy probably stopped forming stars in the packed core. Smaller
galaxies then might have merged with the growing galaxy, making it
expand outward in size over the next 10 billion years, possibly
becoming similar to one of the mammoth, sedate elliptical galaxies seen
today.
"I think our discovery settles the question of whether this mode of
building galaxies actually happened or not," said team member Pieter
van Dokkum of Yale University. "The question now is, how often did this
occur? We suspect there are other galaxies like this that are even
fainter in near-infrared wavelengths. We think they'll be brighter at
longer wavelengths, and so it will really be up to future infrared
telescopes such as NASA's James Webb Space Telescope to find more of
these objects."
CONTACT
Donna Weaver / Ray VillardSpace Telescope Science Institute, Baltimore, Md.
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu
Erica Nelson / Pieter van Dokkum
Yale University
New Haven, Connecticut
203-432-0573
erica.nelson@yale.edu / pieter.vandokkum@yale.edu
Source: HubbleSite
