Sky & Telescope - February 2019 - 84

FOCAL POINT by Anna Barnacka

Image

Observer

Lens

Active galaxy

The Art of Gravitational Lensing
To share the elegant but deeply complex phenomena she studies, an astrophysicist turns to an artist.

sciences have long inﬂuenced the way we
perceive and understand our world. In
the Renaissance, artists focused on accurately depicting depth by using math
to rediscover linear perspective, which
had been lost in medieval times. In the
1880s, artists captured impressions of
their surroundings by exploring the
mixing of light and color as described by
physicist and color theorist Ogden Rood.
Today, however, our scientiﬁc endeavors
have become so dazzlingly complicated
that they limit possibilities to inspire
and communicate.
I use strong gravitational lensing to
uncover complex structures of distant,
active galaxies. In my enthusiasm to
share my research, I've taken listeners on virtual trips from Earth to an
intervening galaxy and beyond it to the
background source it lenses. Like an aircraft marshaller, I've relied on theatrical
hand gestures to guide others along the
multiple paths into which a lensing galaxy splits light. Unfortunately, because
of those trajectories' intricacies, I'd lose
even the most curious people somewhere between the lens and the source.
This was often just before I could share
what I actually work on: the origin of
outbursts from powerful jets launched
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near supermassive black holes within
those background active galaxies.
The challenge to keep my listeners'
attention ended thanks to a collaboration with artist Marlena Bocian Hewitt.
Marlena employs art to empower girls
and promote women in STEAM (Science, Technology, Engineering, Arts,
and Math). Eager to incorporate the
arts into my research, I invited Marlena
to illustrate my work on lensing. After
a dozen drawings, we converged on a
scientiﬁcally satisfying solution, which
Marlena rendered into a captivating
piece of art (above).
The painting beautifully illustrates
a lensed active galaxy with a pair of
relativistic jets (beams of ionized matter accelerated close to the speed of
light). The light escaping the jet travels
toward the observer and encounters
a galaxy along the observer's line of
sight. The intervening galaxy curves
spacetime, which acts as a lens that
magniﬁes and splits the light of the
source along multiple paths. These
paths have differing lengths and
traverse various depths of the lensing
galaxy's gravitational well. As a result,
light traveling different paths arrives
at different times at the observer (note
tiny telescope within the "Observer"

galaxy). We can measure these time
delays, and because they depend on the
location of the source, we can study
them to ﬁ nd out where along the relativistic jet the light originated.
Marlena drew on both cubism and
futurism to depict gravitational lensing.
Interestingly, both cubism and relativity were inspired by the mathematician
Henri Poincaré's work on geometry. In
his general theory of relativity, Einstein used the geometrization of space
and time to predict light bending. In
cubism, Picasso, Braque, and others
abandoned a single viewpoint and relied
on geometric shapes and interlocking
planes to represent reality.
We scientists have to stay true to
the laws of physics and boundaries set
by observations. Thankfully, though,
abstract artists can take a viewer
beyond the four dimensions of spacetime and into a universe limited only by
their imaginations.
¢ ANNA BARNACKA is an astrophysicist
at the Harvard-Smithsonian Center for
Astrophysics and Jagiellonian University in Poland. She is also an inventorturned-entrepreneur. In her free time, she
enjoys neuroscience, martial arts, and
flying airplanes.

M A RLEN A BOCIA N HE WIT T

INTERACTIONS BETWEEN the arts and

Sky & Telescope - February 2019

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