Credit: X-ray: NASA/CXC/Univ. of CA Irvine/D. Buote; Optical: NASA/STScI
Data from NASA's Chandra X-ray Observatory (left) have helped astronomers reveal that a galaxy has more dark matter packed into its core than expected after being isolated for billions of years, as reported in our press release.
The image on the right shows the galaxy called Markarian 1216
(abbreviated as Mrk 1216) in visible light from NASA's Hubble Space
Telescope over the same field of view.
Mrk 1216 belongs to a family of elliptically shaped galaxies that are
more densely packed with stars in their centers than most other
galaxies. Astronomers think they have descended from red, compact
galaxies called "red nuggets" that formed about a billion years after
the Big Bang, but then stalled in their growth about 10 billion years
ago.
If this evolution is correct, then the dark matter in Mrk 1216 and
its galactic cousins should also be tightly packed. To test this idea
for the first time, a pair of astronomers studied the X-ray
brightness and temperature of hot gas at different distances from Mrk
1216's center, so they could "weigh" how much dark matter exists in the
middle of the galaxy. The brighter colors at the center of the Chandra
image represent the increased density of hot gas in the galaxy's core.
According to the new study, a halo, or fuzzy sphere, of dark matter
formed around the stars in the center of Mrk 1216 about 3 or 4 billion
years after the Big Bang. The formation of such a red nugget was typical
for a wide range of elliptical galaxies seen today. However, unlike Mrk
1216, most giant elliptical galaxies continued to gradually grow in
size when smaller galaxies merged with them over cosmic time.
Previously, astronomers estimated that the supermassive black hole
in Mrk 1216 is more massive than expected for a galaxy of its mass.
This most recent study, however, concluded that the black hole mass is
likely to be less than about four billion times the mass of the Sun,
which means it may not be unusually massive for a galaxy as large as Mrk
1216.
Researchers also searched for signs of outbursts from the
supermassive black hole in the center of the galaxy. They saw hints of
cavities in the hot gas similar to those observed in other massive
galaxies and galaxy clusters like Perseus, but more data are needed to confirm their presence.
A paper by David Buote and Aaron Barth (both of the University of
California at Irvine) describing these results appeared in the June 1st
issue of 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 Mrk 1216:
Scale: Image is 1 arcmin (about 85,000 light years) across.
Category: Cosmology/Deep Fields/X-ray Background, Normal Galaxies & Starburst Galaxies
Coordinates (J2000): RA 8h 26m 19.8s | Dec -06° 46´ 23.0"
Constellation: Hydra
Observation Date: June 12, 2015 and Jan 9-14, 2018
Observation Time: 116 hours 7 minutes (4 days 20 hours 7 minutes )
Obs. ID: 17061, 20342, 20924, 20925, 20926
Instrument: ACIS
References: Buote, D.A and Barth A.J., 2019, ApJ; arXiv:1902.02938
Color Code: X-ray: red; Optical: yellow
Distance Estimate: About 295 million light years (z=0.0213)
Scale: Image is 1 arcmin (about 85,000 light years) across.
Category: Cosmology/Deep Fields/X-ray Background, Normal Galaxies & Starburst Galaxies
Coordinates (J2000): RA 8h 26m 19.8s | Dec -06° 46´ 23.0"
Constellation: Hydra
Observation Date: June 12, 2015 and Jan 9-14, 2018
Observation Time: 116 hours 7 minutes (4 days 20 hours 7 minutes )
Obs. ID: 17061, 20342, 20924, 20925, 20926
Instrument: ACIS
References: Buote, D.A and Barth A.J., 2019, ApJ; arXiv:1902.02938
Color Code: X-ray: red; Optical: yellow
Distance Estimate: About 295 million light years (z=0.0213)
Source: NASA’s Chandra X-ray Observatory
