Arp 299 (composite)
Credit: X-ray: NASA/CXC/Univ of Crete/K. Anastasopoulou et al, NASA/NuSTAR/GSFC/A. Ptak et al;
Optical: NASA/STScI
What would happen if you took two galaxies and mixed them together
over millions of years? A new image including data from NASA's Chandra X-ray Observatory reveals the cosmic culinary outcome.
Arp 299 is a system located about 140 million light years
from Earth. It contains two galaxies that are merging, creating a
partially blended mix of stars from each galaxy in the process.
However, this stellar mix is not the only ingredient. New data from
Chandra reveals 25 bright X-ray sources sprinkled throughout the Arp 299
concoction. Fourteen of these sources are such strong emitters of
X-rays that astronomers categorize them as "ultra-luminous X-ray
sources," or ULXs.
These ULXs are found embedded in regions where stars are currently
forming at a rapid rate. Most likely, the ULXs are binary systems where a
neutron star or black hole
is pulling matter away from a companion star that is much more massive
than the Sun. These double star systems are called high-mass X-ray binaries.
Such a loaded buffet of high-mass X-ray binaries is rare, but Arp 299
is one of the most powerful star-forming galaxies in the nearby
Universe. This is due at least in part to the merger of the two
galaxies, which has triggered waves of star formation. The formation of
high-mass X-ray binaries is a natural consequence of such blossoming
star birth as some of the young massive stars, which often form in
pairs, evolve into these systems.
This new composite image of Arp 299 contains X-ray
data from Chandra (pink), higher-energy X-ray data from NuSTAR
(purple), and optical data from the Hubble Space Telescope (white and
faint brown). Arp 299 also emits copious amounts of infrared light that
has been detected by observatories such as NASA's Spitzer Space
Telescope, but those data are not included in this composite.
The infrared and X-ray emission of the galaxy is remarkably similar
to that of galaxies found in the very distant Universe, offering an
opportunity to study a relatively nearby analog of these distant
objects. A higher rate of galaxy collisions occurred when the universe
was young, but these objects are difficult to study directly because
they are located at colossal distances.
The Chandra data also reveal diffuse X-ray emission from hot gas
distributed throughout Arp 299. Scientists think the high rate of supernovas, another common trait of star-forming galaxies, has expelled much of this hot gas out of the center of the system.
A paper describing these results appeared in the August 21st, 2016
issue of the Monthly Notices of the Royal Astronomical Society and is available online.
The lead author of the paper is Konstantina Anastasopoulou from the
University of Crete in Greece. 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 Arp 299:
Scale: Image is 2.8 arcmin across (about 117,000 light years).
Category: Quasars & Active Galaxies, Black Holes
Coordinates (J2000): RA 11h 28m 31.33s | Dec 58° 33´ 41.80"
Constellation: Ursa Major
Observation Date: 13 Jul 2001, 14 Feb 2005, 12-13 Mar 2013
Observation Time: 34 hours 41 minutes
Obs. ID: 1641, 6227, 15077, 15619
Instrument: ACIS
References: Anastasopoulou, K. et al, 2016, MNRAS, 460, 3570; arXiv:1605.07001; Ptak, A. et al, 2014, ApJ, 800, 104; arXiv:1412.3120
Color Code: X-ray (Chandra: Pink; NuSTAR: Blue), Optical (Red, Green, Blue)
Distance Estimate: About 140 million light years
Source: NASA’s Chandra X-ray Observatory
