The magnetic field lines of the the Cigar Galaxy (also called M82)
appear in this composite image. The lines follow the bipolar outflows
(red) generated by exceptionally high rates of star formation. Credit:
NASA/SOFIA/E. Lopez-Rodiguez; NASA/Spitzer/J. Moustakas et al. › Full image and caption
The Cigar Galaxy (also known as M82) is famous
for its extraordinary speed in making new stars, with stars being born 10 times
faster than in the Milky Way. Now, data from the Stratospheric
Observatory for Infrared Astronomy, or SOFIA, have been used to study this
galaxy in greater detail, revealing how material that affects the evolution of
galaxies may get into intergalactic space.
Researchers found, for the first time, that the
galactic wind flowing from the center of the Cigar Galaxy (M82) is aligned along a magnetic field and transports a very large
mass of gas and dust - the equivalent mass of 50 million to 60 million Suns.
"The space between galaxies is not empty," said Enrique Lopez-Rodriguez,
a Universities Space Research Association (USRA) scientist working on the SOFIA
team. "It contains gas and dust - which are
the seed materials for stars and galaxies. Now, we have a better understanding of how this
matter escaped from inside galaxies over time."
Besides being a classic example of a starburst galaxy, which means it is forming an
extraordinary number of new stars compared with most other galaxies, M82 also
has strong winds blowing gas and dust into intergalactic space. Astronomers
have long theorized that these winds would also drag the galaxy's magnetic
field in the same direction, but despite numerous studies, there has been no
observational proof of the concept.
Researchers using the airborne observatory SOFIA
found definitively that the wind from the Cigar Galaxy not only transports a
huge amount of gas and dust into the intergalactic medium, but also drags the
magnetic field so it is perpendicular to the galactic disc. In fact, the wind
drags the magnetic field more than 2,000 light-years across - close to the
width of the wind itself.
"One of the main objectives of this
research was to evaluate how efficiently the galactic wind can drag along the
magnetic field," said Lopez-Rodriguez. "We did not expect to find the
magnetic field to be aligned with the wind over such a large area."
These observations indicate that the powerful
winds associated with the starburst phenomenon could be one of the mechanisms
responsible for seeding material and injecting a magnetic field into the nearby
intergalactic medium. If similar processes
took place in the early universe, they would have affected the fundamental
evolution of the first galaxies.
The results were published in January 2019 in
the Astrophysical Journal Letters.
SOFIA's newest instrument, the High-resolution Airborne Wideband Camera-Plus, or HAWC+, uses far-infrared light to observe celestial dust grains, which align along magnetic field lines. From these results, astronomers can infer the shape and direction of the otherwise invisible magnetic field. Far-infrared light provides key information about magnetic fields because the signal is clean and not contaminated by emission from other physical mechanisms, such as scattered visible light.
"Studying intergalactic magnetic fields -
and learning how they evolve - is key to understanding how galaxies evolved
over the history of the universe," said Terry Jones, professor emeritus at
the University of Minnesota, in Minneapolis, and lead researcher for this
study. "With SOFIA's HAWC+ instrument, we now have a new perspective on these magnetic fields."
The HAWC+ instrument was developed and delivered
to NASA by a multi-institution team led by the Jet Propulsion Laboratory. JPL
scientist and HAWC+ Principal Investigator Darren Dowell, along with JPL
scientist Paul Goldsmith, were part of the research team using HAWC+ to
study the Cigar Galaxy.
SOFIA, the Stratospheric Observatory for
Infrared Astronomy, is a Boeing 747SP jetliner modified to carry a 106-inch
diameter telescope. It is a joint project of NASA and the German Aerospace
Center, DLR. NASA's Ames Research Center in California's Silicon Valley manages
the SOFIA program, science and mission operations in cooperation with the
Universities Space Research Association headquartered in Columbia, Maryland,
and the German SOFIA Institute (DSI) at the University of Stuttgart. The
aircraft is maintained and operated from NASA's Armstrong Flight Research
Center Hangar 703, in Palmdale, California.
News Media Contact
Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469
calla.e.cofield@jpl.nasa.gov
