The firehose

There's some weird stuff going on with M87.

M87 is a supergiant elliptical galaxy in the constellation of Virgo.  It was discovered and catalogued in 1781 by French astronomer Charles Messier -- the "M" designation in many of the brightest nebulae and galaxies comes from their listing in the Messier catalogue -- but the telescopes of his time weren't good enough to make out much detail.  Even through better telescopes it looks like an uninteresting fuzzy blob, mostly because it's 53 million light years away.

This belies its magnitude.  It contains over a trillion stars, and is orbited by around fifteen thousand globular clusters (compare this to the Milky Way's paltry two hundred or so), and has a ginormous black hole at its center with a mass 2.4 billion times that of the Sun.  It is this black hole that you undoubtedly remember from the famous photographs in March of 2021:

[Image licensed under the Creative Commons Event Horizon Telescope, A view of the M87 supermassive black hole in polarised light, CC BY 4.0]

So this is impressive enough as is.  But then the astronomers and astrophysicists starting noticing that the black hole itself was behaving... oddly.

Three weeks ago, a team led by Yuzhu Cui of Shanghai Jiao Tong University published a paper in Nature showing that the black hole at the center of M87 was not only spinning (which isn't at all unusual; most black holes spin) but was precessing.  If you've ever played with a gyroscope, you've seen precession; get it started spinning, and for a little bit it'll stand upright, but then it starts to wobble, and its spin axis traces out a cone that gets wider and wider as the spin rate goes down because of friction.  The Earth precesses, with a period of about 26,000 years, meaning that Polaris wasn't the North Star a few thousand years ago, nor will it be a few thousand years in the future.  Twelve thousand years ago, the North Star was the bright star Vega in the constellation Lyra, made famous as the home of the benevolent aliens in the brilliant movie Contact.

[Image licensed under the Creative Commons Tauʻolunga, Precession N, CC BY-SA 2.5]

So precession of a spinning body isn't that unusual, either, but considering the angular momentum of a 2.4 billion solar mass object, it's kind of surprising that the M87 black hole is precessing fast enough to be observable from 53 million light years away.  But it is -- and its period of precession is only eleven years!

This means that the fountain of radiation and debris being shot out along its spin axis is flailing around like the jet from a loose firehose.  

Then, a new paper -- still in the preprint stages -- has added another bizarre twist.  A team of astrophysicists led by Michael M. Shara, Curator of Astrophysics for the American Museum of Natural History, has found that wherever that wildly-precessing jet nozzle is aimed, there's a higher rate of stars going nova.  Novae are explosions less violent than supernovae (those actually blow the unfortunate star to smithereens); they seem to occur mostly when white dwarf stars accrete matter from nearby dust clouds or by stealing it from a binary star partner, triggering instability and a sudden flare-up.  Here, though, the mechanism isn't understood.  Whether the jet of debris from the black hole is compressing the stars that get in the way and triggering detonation, or if it's simply that the material itself is getting caught by white dwarfs and causing the novae, isn't known.

But it's quite a mental image, isn't it?  A careening jet from a spinning supermassive black hole blasts away at stars in its path, and makes them blow up.

Leaves me feeling glad we live in the tranquil outer reaches of our own galaxy.  I know the Milky Way has its own massive black hole at the center, but out here in quiet stellar suburbia, we're pretty insulated from all that craziness.

I'm perfectly happy hearing about the wild gyrations of M87 -- from a safe vantage point 53 million light years away.

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The black heart of M87

It's awfully easy to get discouraged lately.

The news seems to go from bad to worse every day.  Government corruption, terrorist attacks both here and overseas, every other news story a testament of the amazing ability of Homo sapiens to treat each other horribly.

So when we have a triumph, we should celebrate it.  Because as Max Ehrmann put it, in his classic poem "Desiderata:" "Many persons strive for high ideals; and everywhere life is full of heroism...  With all its sham, drudgery, and broken dreams, it is still a beautiful world."

We got a lovely example of that a couple of days ago, with the revelation that scientists had amassed enough data from the Event Horizon Telescope project to produce the first-ever photograph of a black hole.  It's at the heart of the massive elliptical galaxy M87, in the constellation of Virgo, and is about 54 million light years away.  With no further ado, here's the photo:

I think the left-hand one -- with less magnification -- is even more amazing, because it shows the black hole in context with its surroundings.  It looks more "real."  But in either case, they're stunning.  The glow comes from matter being sucked into the black hole, being heated up to the point of producing x-rays as a sort of electromagnetic death scream before dropping forever beyond the event horizon.  For the very first time, we're seeing an actual image of one of the most bizarre phenomena in nature -- an object so massive that it warps space into a closed curve, so that even light can't escape.

But even this isn't my favorite image that has come out of this study.

This is:

This is Katie Bouman, the MIT postdoc (soon to be starting as an assistant professor at CalTech) whose algorithm made the black hole image a reality.  Bouman responded to her sudden fame with modesty.  "No one of us could've done it alone," she said.  "It came together because of lots of different people from many backgrounds."

Which may well be, but no one is questioning her pivotal role in this groundbreaking achievement.  And what I love about the photograph above is that it perfectly captures the joy of doing science -- what Nobel Prize-winning physicist Richard Feynman called "the pleasure of finding things out."  We now have a window into a piece of the universe that was invisible to us before, and that ineffable feeling is clearly captured in her expression.

There have already been six papers written about this accomplishment, and that's only the beginning.  I find myself wondering what other obscure and fascinating astronomical phenomena Bouman's algorithm could be used to photograph -- and what we might learn from seeing them for real for the first time.  I also wonder what effect that will have on us ordinary laypeople.  The physicists may be comfortable living in the world of their mathematical models (I heard one physicist friend say, "The models are the reality; everything else is just pretty pictures"), but the rest of us need to be more grounded in order to understand.  So what if we were to see more than an artist's conception of things like pulsars, quasars, gamma-ray bursters, type 1-A supernovae?

Kind of a surfeit of wonder, that would be.  But what a way to be overwhelmed, yes?

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This week's Skeptophilia book recommendation is a fun one; Atlas Obscura by Joshua Foer, Dylan Thuras, and Ella Morton.  The book is based upon a website of the same name that looks at curious, beautiful, bizarre, frightening, or fascinating places in the world -- the sorts of off-the-beaten-path destinations that you might pass by without ever knowing they exist.  (Recent entries are an astronomical observatory in Zweibrücken, Germany that has been painted to look like R2-D2; the town of Story, Indiana that is for sale for a cool $3.8 million; and the Michelin-rated kitchen run by Lewis Georgiades -- at the British Antarctic Survey’s Rothera Research Station, which only gets a food delivery once a year.)

This book collects the best of the Atlas Obscura sites, organizes them by continent, and tells you about their history.  It's a must-read for anyone who likes to travel -- preferably before you plan your next vacation.

(If you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!)