Our Supermassive Black Hole Lit up the Milky Way. Is It Trying to Send Us a Message?

Wait, There’s A Supermassive Black Hole In The Center Of Our Galaxy?

Supermassive black holes play a fundamental role in the formation of galaxies. The gravity of the black hole gathers interstellar gas responsible for powering galactic nuclei.

The jets of particles shooting at nearly the speed of light from near the event horizon of a black hole form stars and seeds solar systems. And the sheer mass and weight of a black hole keeps galaxies in place, spinning around them in an endless cosmic dance.

All black holes are formed by the collapse of a star, typically one million of times larger than our sun. They’re extremely dense objects with unimaginable gravity that nothing, not even light, can escape.

This means that scientists such as Do and his team observe the activity of stars and nebulae scattered around the event horizon, rather than the black hole itself.

The flux observed in May is part a familiar pattern this year. The brightness of our black hole, known as Sagittarius A* (Sgr A*), is varying more and reaching brighter levels than regularly observed in the past.

This latest occurrence might have been caused by gases disturbed by the star S0-2 when it passed close to the event horizon back in 2018.

Alternatively, it may be the effect of a possible delayed reaction from when the dust cloud G2 passed in 2014.

This global endeavor was pieced together with many different telescopes observing at many different wavelengths, all staring at M87’s center at the same time. And the trouble was definitely worth it!

The image upholds Einstein’s theory of general relativity.

It is nearly circular and matches the size predicted by theory-informed simulations of what we think the black hole should be.

Why Haven’t We Imaged Our Own Supermassive Black Hole?

While observations are being made of Sgr A* – our galaxy’s supermassive black hole –, taking a similar image is much more difficult.

Sheperd Doeleman of Harvard University and the Harvard-Smithsonian Center for Astrophysics put it quite nicely in a statement in March. From our perspective, the event horizon of Sgr A*

is so small that it’s the equivalent of… being able to read the newspaper in Los Angeles while you’re sitting in New York City.

Another difficulty when trying to photograph Sgr A* is its tendency to brighten and dim over widely varying peaks over short timescales.

Sudden increases, like the flux observed in May, mean regularity in data is less common, and any image is more difficult to resolve.

Is Our Supermassive Black Hole Trying to Send Us a Message?

If the flare of light was in fact our black hole calling out to us from the darkness, we still have some communication issues to work out.

But interstellar observations are always important, whatever form they might take.

Observations made by astronomers like Do and his team and data collected by telescopes around the world bring us closer to a deep understanding of our universe, one flickering image at a time.

Further Reading

Vice. Our Galaxy’s Black Hole Suddenly Lit Up and Nobody Knows Why
[https://www.vice.com/en_us/article/pa7y4m/our-galaxys-black-hole-suddenly-lit-up-and-nobody-knows-why]

Space. First Black Hole Photo By Event Horizon Telescope
[https://www.space.com/first-black-hole-photo-by-event-horizon-telescope.html]

Cosmotography.com. Supermassive Black Holes Drive Galaxy Evolution
[https://www.cosmotography.com/images/supermassive_blackholes_drive_galaxy_evolution_2.html]