Astronomers May Have Found New Way to Map Galaxy Centers

When a star passes too close to the black hole found in the center of a galaxy, the gravitational force is so strong that it shreds the star apart.  As a result, a flare-up is created in the center of the galaxy which fades over a few months.  These flare-ups are called quasars.  A team from the University of Edinburgh led by Professor Andy Lawrence may have discovered a new way to map quasars.  In a large scale survey using the PanSTARRS telescope on Hawaii, Professor Lawrence and his team studied millions of galaxies.  While they did find flare-ups, their behavior was different from their initial “star-shredding” predictions.

Unlike normal quasars that fade over a couple months, the ones found by Lawrence and his team faded over a period of years.  In addition to this finding, the quasars appeared to be at the wrong distance.  Lawrence’s survey identified the quasars to be roughly 10 billion light years away while the galaxies they appeared to be in were only 3 billion light years away.  Should the estimated distances of these quasars and galaxies be correct, then Lawrence and his team are actually viewing quasars through a foreground galaxy.

Normally this occurrence has little effect on the brightness of a quasar, but if a single star in the foreground galaxy passes directly in front of the quasar, the resulting gravitational focusing of the light makes the quasar temporarily brighter.  This phenomenon, called “microlensing,” has been known for low-level flickering, but this is the first time it has been suggested for such intense effects.

Lawrence believes that this finding could help us map out the internal structure of quasars in a way that is otherwise impossible since quasars are so small.  As astronomers discover more developments on this phenomenon, it will dramatically reshape the way we understand the galaxy.