Astronomers have made the most detailed study yet of an extremely massive young galaxy cluster using three of NASA's Great Observatories, as described in our latest press release . This multi-wavelength image shows this galaxy cluster, called IDCS J1426.5+3508 (IDCS J1426 for short), in X-rays
from the Chandra X-ray Observatory in blue, visible light from the
Hubble Space Telescope in green, and infrared light from the Spitzer
Space Telescope in red.
This rare galaxy cluster, which is located 10 billion light years
from Earth, weighs almost 500 trillion Suns. This object has important
implications for understanding how these mega-structures formed and
evolved early in the Universe. Astronomers have observed IDCS J1426 when
the Universe was less than a third of its current age. It is the most
massive galaxy cluster detected at such an early age.
First discovered by the Spitzer Space Telescope in 2012, IDCS J1426
was then observed using the Hubble Space Telescope and the Keck
Observatory to determine its distance. Observations from the Combined
Array for Millimeter Wave Astronomy indicated it was extremely massive.
New data from the Chandra X-ray Observatory confirm the galaxy cluster mass and show that about 90% of the mass of the cluster is in the form of dark matter,
the mysterious substance that has so far been detected only through its
gravitational pull on normal matter composed of atoms.
There is a region of bright X-ray emission (seen as blue-white) near
the middle of the cluster, but not exactly at the center. The location
of this "core" of gas suggests that the cluster has had a collision or
interaction with another massive system of galaxies relatively recently,
perhaps within about the last 500 million years. This would cause the
core to "slosh" around like wine in a moving glass and become offset as
it appears to be in the Chandra data. Such a merger would not be
surprising, given that astronomers are observing IDCS J1426 when the
Universe was only 3.8 billion years old. So that an enormous structure
can form so rapidly, scientists think mergers with smaller clusters
would likely play a role in a large cluster's growth.
This core, while still extremely hot, contains cooler gas than its
surroundings. This is the most distant galaxy cluster where such a "cool
core" of gas has been observed. Astronomers think these cool cores are
important in understanding how quickly hot gas cools off in clusters,
influencing the rate of stars at which stars are born. This cooling rate
can be slowed down by outbursts from a supermassive black hole in the
center of the cluster. Apart from the cool core, the hot gas in the
cluster is remarkably symmetrical and smooth. This is another piece of
evidence that IDCS J1426 formed very rapidly and quickly in the early
Universe. Despite the high mass and rapid evolution of this cluster, its
existence does not pose a threat to the standard model of cosmology.
These results were presented at the 227th meeting of the American
Astronomical Society meeting being held in Kissimmee, Florida. A paper
describing these results has been accepted for publication in The
Astrophysical Journal and is available online.
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the
Chandra program for NASA's Science Mission Directorate in Washington.
The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts,
controls Chandra's science and flight operations.
Fast Facts for IDCS J1426.5+3508:
Scale: Image is 1.9 arcmin across (about 3 million light years)
Category: Groups & Clusters of Galaxies
Coordinates (J2000): RA 14h 26m 28.80s | Dec +35° 07' 48.00"
Constellation: Boötes
Observation Date: 05 and 23 March 2014
Observation Time: 27 hours 47 min (1 day 3 hours 47 min)
Obs. ID: 15168, 16321
Instrument: ACIS
References: Brodwin, M. et al. 2015, ApJ (accepted); arXiv:1504.01397
Color Code: X-ray: Blue, Optical: Green, Infrared: Red
Distance Estimate: About 10 billion light years (z=1.75)
Source: NASA’s Chandra X-ray Observatory
