You saw the 1st photo of a black hole? Now see its home galaxy
Earlier this month, scientists unveiled the first-ever photo taken of a black hole. It was a phenomenal achievement, and that image of the hot, glowing donut-shaped ring of gas and dust – surrounding the black hole itself, which can’t be seen – will go down in history as one of the most epic photos in space science. You can thank the Event Horizon Telescope for this first black hole image; this international group worked for years to accomplish it. Now … want some context for the black hole image? The first several images on this page let us step back a bit, to see how the giant black hole – 6.5 billion times more massive than our sun – appears in relation to its host galaxy, Messier 87 (aka M87). It’s a great view!
NASA released the image above – from its orbiting Spitzer Space Telescope – on April 25, 2019. It shows the black hole’s galaxy in the infrared. Although neither the black hole nor its event horizon can be seen here, you can see two massive jets of material being ejected from the event horizon out into space at nearly the speed of light, just one indication of the power of the central black hole. You thought black holes suck in material with gravity so strong that even light can’t escape? That’s true. But other material can become trapped in the disk around a black hole’s event horizon, and later be ejected again back out into deep space.
M87 is very far away – 55 million light-years away from Earth – and has been studied for over 100 years, including by observatories such as the Hubble Space Telescope, the Chandra X-ray Observatory and NuSTAR. The jets were first seen back in 1918, although their connection to a giant black hole was completely unknown at the time. The jets were first noticed by astronomer Heber Curtis as “a curious straight ray” extending from the center of the galaxy. What was this odd feature?
Now, we know that the jets are composed of high-energy material that shoots out of a disk of material that spins rapidly around the black hole. The ejected material moves at incredible speed – almost the speed of light – and can be seen in visible light, infrared light, radio waves and X-rays.
One of the jets is quite prominent, but when the material in it hits the much sparser material in the interstellar medium (the space between the stars of the galaxy), it creates a huge shockwave that is even more visible. The shockwave can only be seen in infrared light and radio waves. This jet is moving almost directly toward Earth, which increases its apparent brightness. We can still see some of the length of the jet, however, since it is slightly offset from our line of sight. At one point, it looks like the jet curves downward a bit; according to scientists, this is where particles in the jet hit gas particles in the interstellar medium and slow down a little.
The other jet is much fainter, since it is moving away from Earth, and just as fast as the other jet. This makes it virtually invisible in all wavelengths. But as with the first jet, the shockwave – which looks like an inverted letter C – is still clearly visible.
Understanding black holes has been a great challenge for astronomers and physicists over the past few decades, but they’ve been making great strides towards that goal. Once considered to be “exotic,” and still among the strangest objects ever discovered, supermassive black holes are now known to be located in the centers of many (if not most) galaxies, including our own, and an untold number of smaller black holes dot the universe. Studying black holes in the context of their galaxies – and having the ability to image them directly – are major steps towards understanding one of these incredible and bizarre phenomena.
Bottom line: Astronomers have released some new images (first two images on this page) of the galaxy M87, home galaxy to the giant black hole whose image you saw a few weeks ago. The images show you the black hole in the context of its galaxy.