Gobble Up These Black (Hole) Friday Deals!

Welcome to our 6th annual annual Black Hole Friday! Check out these black hole deals from the past year as you prepare to

head out for a shopping spree or hunker down at home to avoid the crowds.

First things first, black holes have one basic rule:

They are so incredibly dense that to escape their surface you’d have to travel

faster than light. But light speed is the cosmic speed limit … so nothing

can escape a black hole’s surface!

Black

hole birth announcements

Some black holes form when a very large star

dies in a supernova explosion and collapses

into a superdense object. This is even more jam-packed than the crowds at your

local mall — imagine an object 10 times more massive than the Sun squeezed into

a sphere with the diameter of New York City!

Some of these collapsing stars also signal

their destruction with a huge burst of gamma rays. Our Fermi Gamma-ray Space Telescope and

Neil

Gehrels Swift Observatory continuously seek out the

signals of these gamma ray bursts — black hole birth announcements that

come to us from across the universe.

NICER

black holes

There are loads of stellar mass black holes,

which are just a few 10s of times the Sun’s mass, in our home galaxy alone —

maybe even hundreds of millions of them! Our Neutron Star

Interior Composition Explorer, or NICER for short,

experiment on the International Space Station has been studying some of those relatively nearby black holes.

Near one black hole called GRS 1915+105, NICER found disk

winds — fast streams of gas created by heat or pressure. Scientists are still figuring out some puzzles about these types of wind.

Where do they come from, for example? And do they change the way material falls

into the black hole? Every new example of these disk winds helps astronomers

get closer to answering those questions.

Merging

monster black holes

But stellar mass black holes aren’t the only

ones out there. At the center of nearly every large galaxy lies a supermassive

black hole — one with the mass of millions or billions of Suns smooshed into a region no bigger than our solar

system.

There’s still some debate about how these

monsters form, but astronomers agree that they certainly can collide and

combine when their host galaxies collide and combine. Those black holes will

have a lot of gas and dust around them. As that material is pulled into the

black hole it will heat up due to friction and other forces, causing it to emit light.  A group of scientists wondered what light it

would produce and created this mesmerizing visualization showing that most of the light

produced around these two black holes is UV or X-ray light.

We can’t see those wavelengths with our own eyes, but many telescopes can.

Models like this could help scientists know what to look for to spot a merger.

Black

holes power bright gamma ray lights

It also turns out that these supermassive

black holes are the source of some of the brightest objects in the gamma ray

sky! In a type of galaxy called active galactic nuclei (also called “AGN” for short)

the central black hole is surrounded by a disk of gas and dust that’s

constantly falling into the black hole.

But not only that, some of those AGN have jets

of energetic particles that are shooting out from near the black hole at nearly

the speed of light! Scientists are studying these jets to try to understand how

black holes — which pull everything in with their huge amounts of gravity —

provide the energy needed to propel the particles in these jets. If that jet is

pointed directly at us, it can appear super-bright in gamma rays and we call it

a blazar. These blazars make up more than half of the sources our Fermi

space telescope sees.

Catching

particles from near a black hole

Sometimes scientists get a two-for-one kind of

deal when they’re looking for black holes. Our colleagues at the IceCube Neutrino Observatory

actually caught a particle from a blazar 4 billion light-years

away. IceCube lies a mile under the ice in Antarctica and

uses the ice itself to detect neutrinos, tiny speedy particles that weigh

almost nothing and rarely interact with anything. When IceCube caught a

super-high-energy neutrino and traced its origin to a specific area of the sky,

they turned to the astronomical community to pinpoint the source.

Our Fermi spacecraft scans the entire sky

about every three hours and for months it had observed a blazar producing more

gamma rays than usual. Flaring is a

common characteristic in blazars, so this didn’t attract

special attention. But when the alert from IceCube came through, scientists

realized the neutrino and the gamma rays came from the same patch of sky! This

method of using two or more kinds of signals to learn about one event or object

is called multimessenger astronomy, and it’s helping us learn a lot about the

universe.

Get more fun facts and information about black

holes HERE

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