Researchers using the Gemini North telescope on Hawai’i’s Maunakea have
detected the most energetic wind from any quasar ever measured. This outflow,
which is travelling at nearly 13% of the speed of light, carries enough energy
to dramatically impact star formation across an entire galaxy. The
extragalactic tempest lay hidden in plain sight for 15 years before being
unveiled by innovative computer modeling and new data from the international
Gemini Observatory.
The most
energetic wind from a quasar has been revealed by a team of astronomers using
observations from the international Gemini Observatory, a program of NSF’s
NOIRLab. This powerful outflow is moving into its host galaxy at almost 13% of
the speed of light, and stems from a quasar known as SDSS J135246.37+423923.5
which lies roughly 60 billion light-years from Earth.
“While
high-velocity winds have previously been observed in quasars, these have been
thin and wispy, carrying only a relatively small amount of mass,” explains
Sarah Gallagher, an astronomer at Western University (Canada) who led the
Gemini observations. “The outflow from this quasar, in comparison, sweeps along
a tremendous amount of mass at incredible speeds. This wind is crazy powerful,
and we don’t know how the quasar can launch something so substantial.” [1]
As well as
measuring the outflow from SDSS J135246.37+423923.5, the team was also able to
infer the mass of the supermassive black hole powering the quasar. This
monstrous object is 8.6 billion times as massive as the Sun -about 2000 times
the mass of the black hole in the center of our Milky Way and 50% more massive
than the well-known black hole in the galaxy Messier 87.
This result is published in the Astrophysical Journal and the
quasar studied here now holds the record for the most energetic quasar wind
measured to date, with a wind more energetic than those recently reported in a
study of 13 quasars [2].
Despite its mass
and energetic outflow, the discovery of this powerhouse languished in a quasar
survey for 15 years before the combination of Gemini data and the team’s
innovative computer modeling method allowed it to be studied in detail.
“We were shocked
— this isn’t a new quasar, but no one knew how amazing it was until the team
got the Gemini spectra,” explains Karen Leighly, an astronomer at the
University of Oklahoma who was one of the scientific leads for this research.
“These objects were too hard to study before our team developed our methodology
and had the data we needed, and now it looks like they might be the most
interesting kind of windy quasars to study.”
Quasars — also
known as quasi-stellar objects — are a type of extraordinarily luminous
astrophysical object residing in the centres of massive galaxies [3].
Consisting of a supermassive black hole surrounded by a glowing disk of gas,
quasars can outshine all the stars in their host galaxy and can drive winds
powerful enough to influence entire galaxies [4].
“Some
quasar-driven winds have enough energy to sweep the material from a galaxy that
is needed to form stars and thus quench star formation,” explains Hyunseop
(Joseph) Choi, a graduate student at the University of Oklahoma and the first
author of the scientific paper on this discovery. “We studied a particularly
windy quasar, SDSS J135246.37+423923.5, whose outflow is so thick that it’s
difficult to detect the signature of the quasar itself at visible wavelengths.”
Despite the
obstruction, the team was able to get a clear view of the quasar using the
Gemini Near-Infrared Spectrograph (GNIRS) on Gemini North to observe at
infrared wavelengths. Using a combination of high-quality spectra from Gemini
and a pioneering computer modeling approach, the astronomers uncovered the
nature of the outflow from the object — which proved, remarkably, to be more
energetic than any quasar outflow previously measured.
The team’s
discovery raises important questions, and also suggests there could be more of
these quasars waiting to be found.
We don’t know
how many more of these extraordinary objects are in our quasar catalogs that we
just don’t know about yet,” concludes Choi “Since automated software generally
identifies quasars by strong emission lines or blue color — two properties our
object lacks — there could be more of these quasars with tremendously powerful
outflows hidden away in our surveys.”
“This
extraordinary discovery was made possible with the resources provided by the
international Gemini Observatory; the discovery opens new windows and
opportunities to explore the Universe further in the years to come,” said Martin
Still, an astronomy program director at the National Science Foundation, which
funds Gemini Observatory from the U.S. as part of an international
collaboration. “The Gemini Observatory continues to advance our knowledge of
the Universe by providing the international science community with forefront
access to telescope instrumentation and facilities.”
Notes
[1] The colossal
energy carried by the quasar outflow is a product of both the speed of the wind
and the amount of mass it carries. An intuitive way to understand this is to
compare a freight train and a champion sprinter — while both travel at roughly
the same speed, the more massive freight train has far more momentum and
energy.
[2] This result
is independent of the recent NASA/STScI press release on quasar winds which
focused on strong winds in 13 other quasars.
[3] Quasars take
their name from their first identification in the 1950’s at radio wavelengths.
Quasar is a contraction of quasi-stellar radio source, a name chosen to reflect
the starlike appearance of these radio sources when viewed at visible
wavelengths.
[4] The gas
feeding a quasar surrenders energy in the form of light as it falls into the
central black hole. This emitted light is both the origin of a quasar’s
luminosity and the source of the energy that drives outflows.
Journal article: https://iopscience.iop.org/article/10.3847/1538-4357/ab6f72
No comments:
Post a Comment