The night sky has always played a crucial role in navigation, from early ocean crossings to modern GPS. Besides stars, the United States Navy uses quasars as beacons. Quasars are distant galaxies with supermassive black holes, surrounded by brilliantly hot disks of swirling gas that can blast off jets of material. Following up on the groundbreaking 2020 discovery of newborn jets in a number of quasars, aspiring naval officer Olivia Achenbach of the United States Naval Academy has used NASA’s Hubble Space Telescope to reveal surprising properties of one of them, quasar J0742+2704.
"The biggest surprise was seeing the distinct spiral shape in the
Hubble Space Telescope images. At first I was worried I had made an
error," said Achenbach, who made the discovery during the course of a
four-week internship.
Quasar J0742+2704 (center) became the subject of
astronomers' interest after it was discovered to have a newborn jet blasting
from the disk around its supermassive black hole in 2020, using the Karl G.
Jansky Very Large Array (VLA) radio observatory. This led to follow-up with
other observatories in an effort to determine the properties of the galaxy and
what may have triggered the jet. While the jet itself cannot be seen in this
Hubble Space Telescope infrared-light image, the spiral shape of J0742+2704 is
clear, with faint but detectable arms branching above and below the galaxy
center. This was a big surprise to the research team, as quasars hosting jets
are typically elliptical-shaped, and its suspected that messy mergers with
other galaxies are what funnel gas toward the black hole and fuel jets. These
mergers would also disrupt any spiral formation a galaxy may have had before
mixing its contents with another galaxy. Though its intact spiral shape means
it has not experienced a major merger, Hubble does show evidence that its lower
arm has been disrupted, possibly by the tidal forces of interaction with
another galaxy. This could mean that jets can be triggered by a far less
involved, dramatic interaction of galaxies than a full merger. The large galaxy
to the lower right of the quasar appears to be a ring galaxy, another sign of
interaction. Some ring galaxies form after a small galaxy passes through the
center of a larger galaxy, reconfiguring its gas and dust. The brightest parts
of this image — foreground stars and the bright center of the quasar — show the
characteristic "starry" spikes produced by Hubble (and other
telescopes') interior structure. They are not actual aspects of the cosmic
objects.
NASA, ESA, Kristina Nyland (U.S. Naval Research Laboratory); Image Processing: Joseph DePasquale (STScI)
“We typically see quasars as older
galaxies that have grown very massive, along with their central black holes,
after going through messy mergers and have come out with an elliptical shape,”
said astronomer Kristina Nyland of the Naval Research Laboratory, Achenbach’s
adviser on the research.
"It's extremely rare and exciting to find a quasar-hosting galaxy
with spiral arms and a black hole that is more than 400 million times the mass
of the Sun — which is pretty big — plus young jets that weren't detectable 20
years ago," Nyland said.
The unusual quasar takes its place amid an active debate in the
astronomy community over what triggers quasar jets, which can be significant in
the evolution of galaxies, as the jets can suppress star formation. Some
astronomers suspect that quasar jets are triggered by major galaxy mergers, as
the material from two or more galaxies mashes together, and heated gas is
funneled toward merged black holes. Spiral galaxy quasars like J0742+2704,
however, suggest that there may be other pathways for jet formation.
While J0742+2704 has maintained its spiral shape, the Hubble image does show intriguing signs of its potential interaction with other galaxies. One of its arms shows distortion, possibly a tidal tail.
Hubble captured intriguing hints of interaction, if
not full merging, between galaxies including quasar J0742+2704. There is
evidence of a distorted tidal tail, or a streamer of gas, that has been pulled
out by the gravity of a nearby galaxy. The presence of a ring galaxy also
suggests interaction: The distinctive shape of ring galaxies are thought to
form when one galaxy passes through another, redistributing its contents into a
central core circled by stars and gas. Astronomers will be doing further analysis
of Hubble's detailed spectroscopic data, plus follow-up with other telescopes
that can see different types of light, to confirm the distances of the galaxies
and how they may be affecting one another.
NASA, ESA, Kristina Nyland (U.S. Naval Research
Laboratory); Image Processing: Joseph DePasquale (STScI)
"Clearly there is something
interesting going on. While the quasar has not experienced a major disruptive
merger, it may be interacting with another galaxy, which is gravitationally
tugging at its spiral arm," said Nyland.
Another galaxy that appears nearby
in the Hubble image (though its location still needs to be spectroscopically
confirmed) has a ring structure. This rare shape can occur after a galaxy
interaction in which a smaller galaxy punches through the center of a spiral
galaxy. "The ring galaxy near the quasar host galaxy could be an
intriguing clue as to what is happening in this system. We may be witnessing
the aftermath of the interaction that triggered this young quasar jet,"
said Nyland.
Both Achenbach and Nyland emphasize
that this intriguing discovery is really a new starting point, and there will
be additional multi-wavelength analysis of J0742+2704 with data from
NASA's Chandra
X-ray Observatory and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.
It's also a case for keeping our eyes on the skies, said Achenbach.
"If we looked at this galaxy
20 years, or maybe even a decade ago, we would have seen a fairly average
quasar and never known it would eventually be home to newborn jets," said
Achenbach. "It goes to show that if you keep searching, you can find
something remarkable that you never expected, and it can send you in a whole
new direction of discovery."
The Hubble Space Telescope has been
operating for over three decades and continues to make ground-breaking
discoveries that shape our fundamental understanding of the universe. Hubble is
a project of international cooperation between NASA and ESA (European Space
Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the
telescope and mission operations. Lockheed Martin Space, based in Denver, also
supports mission operations at Goddard. The Space Telescope Science Institute
in Baltimore, which is operated by the Association of Universities for Research
in Astronomy, conducts Hubble science operations for NASA.
Source: Hubble Reveals Surprising Spiral Shape of Galaxy Hosting Young Jet - NASA Science
No comments:
Post a Comment