When a hole eats a hole

Because the Universe is stranger than we can imagine, it winds up featuring massive objects that operate on scales that dwarf not just human achievement, but even the significance of our entire galaxy. Case in point, OJ 287.

As reported by Phil Plait in his “Bad Astronomy” blog on Syfy.com, OJ 287 is a cosmic object called a “blazar”, a particularly active type of quasar, whose supermassive black hole (SMBH) at the galactic nucleus unleashes enough energetic radiation that we can comfortably (and safely) see it from 3.5 billion light-years away. But twice every 12 years, OJ 287 flares up in the visible light portion of the spectrum.

Astronomers have theorized that the SMBH at OJ 287’s core (weighing in at 18.4 billion times the mass of our Sun) has a binary buddy, another SMBH (totaling a mere 150 million Solar masses – by comparison, the Milky Way’s SMBH is a tiny 4 million Solar masses). The smaller SMBH orbits the larger one, and it periodically crashes through the accumulated material in equatorial orbit around the giant SMBH, known as its accretion disk.

Artistic illustration of OJ 287 binary black hole system.
Credit: Dey et al., Astrophysics Journal, 2018, 866, 11. (c)AAS, 2018

When the secondary SMBH collides, the “friction” of its passage through the dust cloud heats up the material enough to produce a visible light “flare” equivalent to a trillion (with a ‘t’!) stars, outshining most galaxies.

What makes this science story most wonderful is that these unimaginably mighty events are *predictable*, as astronomers, applying Einstein’s General Theory of Relativity, were able work out not only the orbit but the precession as well; the central SMBH bends spacetime enough to shift the orbit by 39o each time the smaller SMBH passes by. The result was a predicted flare that was within 4 hours of the observed “spike” on July 31, 2019, in OJ 287’s light curve.

So even if we cannot imagine the wonders of the Universe before we discover them, we can train our imaginations to encompass the things that we do finally find.

1 Comment

  1. kevin

    First thing I look for every morning is a new Bad Astronomy post. And not just because Phil hails from my home town. Its a fabulous, awe inspiring, and humbling blog.

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