Our First Galaxy

The current most distant object has the catchy name JADES-GS-z14-0, about 98% of the way back to the beginning of our known universe. NASA’s JWST is constantly pushing the limit of how far we can see in space and time. Using its giant mirror and supercooled detectors astronomers are finding ever fainter and surprising young galaxies.

Can we see all the way back to the “First Galaxy”? Let’s start at the beginning…

Beyond the Earth, Moon, Sun, planets, and stars that fill the night sky with awe, beyond the vast expanse of the Milky Way, there is one object we can see with the naked eye, the Andromeda galaxy, that was the most distant known to humanity – until 1923. That’s when Edwin Hubble observed individual stars in what had previously been only a spiral blur or nebula. The “Andromeda Nebula” was actually made of stars, in a form similar to the Milky Way. Hubble estimated the distance at almost 1 million light years!

The realization that there was another galaxy revolutionized astronomy. (Hubble would achieve that a second time, and even more spectacularly, when he discovered the Big Bang. More on that later.) Andromeda remains the most distant object widely visible without a telescope. But once astronomers knew there was another galaxy, they began looking for more. And they found many, among other nebulae that had been observed with telescopes, before they had the detail to see that they were full of stars.

Hubble and collaborators assembled a list of galaxies that they could measure the “red shift” of, by way of a spectroscope. Redshift is the astronomers term for a Doppler effect; light waves seem closer together when they are moving towards us, and further apart when they move away. The galaxy moving away from the telescope looks more red.

Hubble found a clear mathematical relationship between the red shift and the distance and velocity of the galaxy. This is called Hubble’s law, and gave us a new most distant galaxy. NGC 7619 is 171 million light years away from us.

This discovery began a race to find the most distant galaxies, and the leader was an astronomer named Milton Humason, who began as a janitor working at Mt Wilson and became a prominent astronomer. He frequently published new records starting with NGC 4860 at 360 million (M) light years and finished with the Bootes Cluster at 800 M. Then the research paused for WWII.

After the war the 100 inch telescope at Mt. Wilson was succeeded by the 200 inch at Mt. Palomar. These were amazing engineering feats, look at the size of the telescope in the 1940s! Now we could see much further.

Humason was back and found the faintest galaxy in the Hydra cluster was over 2 billion (B) light years away. The Universe was now approaching a million times larger than we knew only 20 years before. This era of research 1900-1950 is admired as a Golden Age of Physics and Astronomy.

In 1960 the record was smashed by 3C 295, a radio galaxy located in the constellation of Boötes about 5B light years from Earth. The next record was by Schmidt who, in 1964 ,found 3C 147 at over 6B light years ( ly) from earth. This was another galaxy first discovered by radio astronomy, and marked the start of Quasars as the most distant known galaxies. Quasar comes from Quasi Stellar Radio object, and refers to objects that are extremely bright in radio, like a nearby star, but incredibly far away. Quasars were so bright that they were a puzzle for decades, and an inspiration for work on Black Holes.

What we’re seeing in a quasar is a galaxy with a supermassive black hole that’s exceptionally active, with a bright jet coming from the accretion disk around the black hole — but that wasn’t understood until observations from the Hubble Space Telescope in the 90s.

The next year, in 1965, Schmidt and collaborators discovered 3C 245 was 10.5 B ly from us. A huge advance that made it to Time magazine. This is also well into the distance and expansion velocity range where relativity becomes the dominant factor in physics. And the light is shifted into the infrared because of cosmic expansion. That means it gets increasingly difficult to find and measure galaxies. Adding even a hundred million light years distance to the next object is now a major technical challenge. Astronomers use a factor called z to measure redshift and we’ll start including that as another way to understand how incredibly distant and different the early distant universe is from today.

Incremental advances were made in the 70s and early 80s, until in 1987 Warren and team found a quasar at redshift z = 4 – over 12B ly from earth. Then more incremental advances until 1991 when Schneider and Schmidt found PC 1247 + 3404 at z = 4.9 at 12.7B ly. Then in 1997 something besides a quasar became the most distant galaxy for the first time in 40 years!

Franx and team found a cluster called CL1358+62 ,using the brand new Hubble telescope, and you can see it above. In the cluster they saw a tiny red arc. And that was amazing.

On close study that arc is actually the warped and magnified image of an extremely distant galaxy, made visible by phenomena called “gravitational lensing.” Einstein predicted that light from a distant object could be bent by the gravity of a large object in front of it, like a supercluster of galaxies. This focuses the light just like a cosmic size telescope, and magnifies the image hundreds of times. The first Lens had been discovered in 1979, and now a practical use was found for them. Today it’s a whole field of study.

At z = 4.9 the galaxy is 12.6 B ly away, and the gravity lens enabled the team to see a smaller companion galaxy also. Redshift 5 and 6 were incrementally achieved from 1998 to 2006. The two most notable are HDF 4, that was discovered in the world famous Hubble deep field of 1998 by Weymann and a large team, and IOK – 1 in 2006 using the ground-based Subaru telescope in Hawaii, by Iye and team.

Hawaii began playing a vital role in discovering distant galaxies when the twin Keck Telescopes were built in the 90s. They can measure the spectrum of extremely distant objects using several new technologies, if they know where to look.

It’s mind boggling to think that the deep field is an image of “empty space” that has no visible objects seen in previous telescopes. 10K+ galaxies that no one knew were there. All distant, yet huge. HDF 4 is 12.7 B ly away. IOK – 1 is12.8 B ly. These are from the first billion years of our Universe, when many mysterious and important events happened. It’s called Cosmic Dawn.

In 2009 something different and unexpected happened, a gamma ray burst. We don’t know what causes these, possibly gigantic supernovas, but astronomers were ready. GRB 090423 was found by the Swift space telescope and ground based observations by Tanvir and a large team, found a redshift spectrum. At z = 8.2 giving a distance of 13.2 B ly, back to within 500 million years after the Big Bang. This caused theoretical cosmology to begin a re-think on how early galaxies could form. That would happen again with JWST.

After a dozen years of controversial studies at the limit of Hubble and Keck, there was a new Space Telescope, the JWST. In 2023 a galaxy called JADES GS Z13 was measured by Curtis-Lake using JWST, at a redshift of 13. Less than 300 million years after the Big Bang! This is a huge deal. It meant we could now see the very first galaxies in the Universe, and maybe the very first stars.

The current most distant galaxy known is JADES-GS-z14-0, discovered in 2024 by JWST astronomers. It appears to be made almost entirely of young stars. Our best guess on how that happened so fast is early dark energy, and the new distance record is constantly being broken. The first galaxy may already be visible.

For the curious, here is a link to a Flikr repository of over 100 more images from the James Webb Space James Web Space Telescope.