NRL Finds Supermassive Black Holes Launching
New Radio Jets by U.S. Naval Research Laboratory
November 24, 2020
U.S. Naval Research Laboratory researchers led a team of
scientists who discovered some of the youngest known radio jets
launched by growing supermassive black holes in the centers of
distant galaxies.
October 26, 2020 - Illustration of a young radio jet launching from a supermassive black hole in the center of a distant galaxy. (U.S. Naval Research Laboratory
illustration by Daniel Parry)
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Watching and recording the jets, which are believed to be only
decades old, in their infancy allows researchers to observe their
formation and growth and study how they influence their
environments.
"Timing and navigation are a fundamental
portion of the Navy mission and constitute part of the key
infrastructure the DOD relies on,” said Henrique Schmitt, Ph.D., an
astronomer at NRL. "Understanding the evolution of jets in active
galaxies is important for day-to-day tools like GPS. Such active
galaxies define the celestial reference frame from which precision
timing and positioning are derived.”
The team discovered the
jets after reviewing images from the Very Large Array Sky Survey
(VLASS) that contained unusually bright radio sources in comparison
to previous studies with the Karl G. Jansky Very Large Array (VLA)
in Socorro, New Mexico. Their findings are published in The
Astrophysical Journal.
“This is a new topic that has yet to
be fully explored,” said Kristina Nyland, Ph.D., a National Research
Council postdoctoral fellow in residence at NRL. “Studying the
launching of powerful jets is important for us to understand how
galaxies and supermassive black holes grow in tandem over billions
of years.”
According to Nyland, older jets shine for millions
of years and may extend far beyond the confines of their host
galaxies, while newborn jets stay within the boundaries of their
hosts. Known as the interstellar medium, this area contains the raw
materials that give rise to new stars and planetary systems. It is
hypothesized newborn jets may interact with these dense clouds of
gas and play an important role in galaxy formation and evolution.
“When you have compact, powerful jets of radio plasma
colliding with a reservoir of star-forming gas, the jets may alter
the efficiency of new stellar births and the future appearance and
properties of the galaxy,” Nyland said. “Studying young jets in
particular is essential for understanding our cosmic origins. It is
important for us to measure the rate at which new jets are launched
by supermassive black holes to ultimately understand how they
influence the lives of the galaxies in which they reside.”
The U.S. Naval Observatory (USNO) maintains a celestial reference
frame used to provide a reference of the skies and space. That
celestial reference frame appears in grid form and encompasses more
than 4,000 known radio sources. New radio sources, like newborn
jets, can add reference points to the grid.
Living On The Grid
Reference points on the grids can change in appearance over time.
Researchers are trying to fill in sparse areas of the grid by
coupling an optical reference frame to the celestial reference
frame. However, the physics of the optical and radio energy
emissions from the supermassive black holes are not fully
understood. These emissions look different over time and researchers
find that when optical and celestial grids are overlaid they do not
always match up perfectly.
“Without understanding the
physics of those radio sources, what you see is those two reference
frames don’t always line up,” said Tracy Clarke, Ph.D., a radio
astronomer in NRL’s Remote Sensing Division. “That’s because we are
looking at a different part of the radio source compared to the
optical host galaxy—they are shifted a bit.”
“Understanding
the source of radio emission from AGN is a key area of interest to
the USNO and the Navy, and helps us better understand the nature of
the quasar sources that comprise the International Celestial
Reference Frame,” said Megan Johnson, Ph.D. at USNO.
Numerous
studies are underway to gain a better understanding of the physics.
That information could be used to build a more comprehensive and
predictive reference frame. Navy assets can utilize the reference
frame in a GPS constrained environment. To do that, researchers want
to give operators the sources of bias in a fixed grid (such as a
shift in brightness in one of the jet sources) to offset the
reference frame.
“The physics of what Kristina Nyland is
doing helps us understand how to tie those two reference frames
tightly together, and that’s going to give the Navy a fantastic
multi-wavelength reference frame,” Clarke said.
Clarke
currently serves as co-chair of the Survey Science Group for the VLA
Sky Survey (VLASS). This group played a key role in developing the
VLASS survey and it currently serves as the interface to the
scientific community.
Astronomical Collaboration
VLASS is building a richer
understanding of space by combining imagery and data of the entire
sky visible from a telescope taken multiple times over several
years. NRL is supporting the VLASS through commensal observations
with the VLA Low Band Ionosphere and Transient Experiment (VLITE),
operated out of NRL. VLITE is a powerful addition to the survey,
providing complementary information on radio source properties over
a different range of frequencies and spatial scales.
“While VLASS data have allowed the discovery of these
newly formed jets, understanding the history of galaxy evolution may
require additional radio data,” Clarke said. “This is where VLITE
comes in. VLITE operates at longer observing wavelengths and
observes in parallel to VLASS.”
Clarke believes VLITE is a
powerful addition to the survey since it provides complementary
information on radio source properties that allows NRL researchers
to better understand the evolution of the supermassive black hole
that is powering each newborn radio jet.
Nyland is leading
the research project in the remote sensing division of NRL through
the NRC postdoctoral fellowship program. She continues to study the
newborn jets and observe how they change over time.
“This
research contributes overall to human exploration,” said Nyland. “It
contributes to a richer understanding of fundamental physics and the
fascinating link between supermassive black holes and galaxy
evolution.”
About the U.S. Naval Research Laboratory
The remote sensing division
conducts basic research, science, and applications aimed at the
development of new concepts for passive sensors and imaging systems
for objects and targets on the Earth, in the near-Earth environment,
and in deep space.
NRL
is a scientific and engineering command dedicated to research that
drives innovative advances for the Navy and Marine Corps from the
seafloor to space and in the information domain. NRL is located in
Washington, D.C., with major field sites in Stennis Space Center,
Mississippi; Key West, Florida; and Monterey, California, and
employs approximately 2,500 civilian scientists, engineers and
support personnel.
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