Black Hole Ilustration
Credit: X-ray: NASA/CXC/ICE/M.Mezcua et al.;
Credit: X-ray: NASA/CXC/ICE/M.Mezcua et al.;
Infrared: NASA/JPL-Caltech;
Illustration: NASA/CXC/A.Hobart
This image shows data from a massive observing campaign that includes NASA's Chandra X-ray Observatory. These Chandra data have provided strong evidence for the existence of so-called intermediate-mass black holes
(IMBHs). Combined with a separate study also using Chandra data, these
results may allow astronomers to better understand how the very largest
black holes in the early Universe formed, as described in our latest press release.
The COSMOS ("cosmic evolution survey") Legacy Survey has assembled
data from some of the world's most powerful telescopes spanning the electromagnetic spectrum.
This image contains Chandra data from this survey, equivalent to about
4.6 million seconds of observing time. The colors in this image
represent different levels of X-ray energy detected by Chandra. Here the
lowest-energy X-rays are red, the medium band is green, and the
highest-energy X-rays observed by Chandra are blue. Most of the colored
dots in this image are black holes. Data from the Spitzer Space
Telescope are shown in grey. The inset shows an artist's impression of a growing black hole in the center of a galaxy. A disk of material surrounding the black hole and a jet of outflowing material are also depicted.
Two new separate studies using the Chandra COSMOS-Legacy survey data
and other Chandra data have independently collected samples of IMBHs, an
elusive category of black holes in between stellar mass black holes and the supermassive black holes found in the central regions of massive galaxies.
One team of researchers identified 40 growing black holes in dwarf
galaxies. Twelve of them are located at distances more than five billion
light years
from Earth and the most distant is 10.9 billion light years away, the
most distant growing black hole in a dwarf galaxy ever seen. Most of
these sources are likely IMBHs with masses that are about 10,000 to
100,000 times that of the Sun.
A second team found a separate, important sample of possible IMBHs in
galaxies that are closer to Earth. In this sample, the most distant
IMBH candidate is about 2.8 billion light years from Earth and about 90%
of the IMBH candidates they discovered are no more than 1.3 billion
light years away.
They detected 305 galaxies in their survey with black hole masses less than 300,000 solar masses. Observations with Chandra and with ESA's XMM-Newton of a small part of this sample show that about half of the 305 IMBH candidates are likely to be valid IMBHs. The masses for the ten sources detected with X-ray observations were determined to be between 40,000 and 300,000 times the mass of the Sun.
IMBHs may be able to explain how the very biggest black holes, the supermassive ones, were able to form so quickly after the Big Bang.
One leading explanation is that supermassive black holes grow over time
from smaller black holes "seeds" containing about a hundred times the
Sun's mass. Some of these seeds should merge to form IMBHs. Another
explanation is that they form very quickly from the collapse of a giant
cloud of gas with a mass equal to hundreds of thousands of times that of
the Sun. There is yet to be a consensus among astronomers on the role
IMBHs may play.
A paper describing the COSMOS-Legacy result by Mar Mezcua (Institute
for Space Sciences, Spain) and colleagues was published in the August
issue of the Monthly Notices of the Royal Astronomical Society and is available online.
The paper by Igor Chilingarian (Harvard-Smithsonian Center for
Astrophysics) on the closer IMBH sample is being published in the August
10th 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 COSMOS Legacy Survey:
Category: Black Holes, Cosmology/Deep Fields/X-ray Background
Constellation: Sextans
Observation Date: 68 pointings between Nov 2012 and March 2014
Observation Time: 1277 hours (53 days 5 hours)
Obs. ID: 15207-15262, 15590, 15591, 15598, 15600, 15604-15606, 15649, 15653, 15655, 16544, 16562
Instrument: ACIS
References: Mezcua, M. et al., 2018, MNRAS, 478, 2576; arXiv:1802.01567; [Non-COSMOS study: Chilingarian, I. et al., 2018, ApJ, 873, 1; arXiv:1805.01467]
Distance Estimate: About 410 million to 11.0 billion light years
