Kevin Hainline: Seeker of the Faraway

 

Dr. Kevin Hainline sings in a choir, fills his friends’ homes with watercolor art, and is the first person to have seen the most distant galaxy known to humankind. 

 

Before his paper came out earlier this month (read more about it here), Hubble Space Telescope data didn’t show a clear picture of how many—if any—galaxies existed in the young universe. The James Webb Space Telescope Advanced Deep Extragalactic Survey (JADES) team, co-led by Steward Observatory’s Marcia Rieke, revealed that galaxies were forming less than 600 million years after the Big Bang—and lots of them. Hainline uses this analogy: imagine that the timeline of the universe is a party, and that galaxies are guests—until JWST, astronomers imagined that galaxies didn’t start showing up for the party until quite late. But his latest paper shows that “as far back as we go in the party, people are showing up, and there’s a lot of them. In the first five minutes of a two-hour party, things are happening.” 

 

Understanding when galaxies first began forming in the storyline of the universe is an act of understanding our own origins. In the first moments after the Big Bang, says Hainline, the universe was made of light energy. Quite quickly, that energy slowed and cooled enough to became basic particles—mostly hydrogen and helium. But life as we know it is built from more diverse elements like carbon, nitrogen, and oxygen, Hainline explains, wiggling his fingers to demonstrate the complexity of the human body. In part, JWST was designed to sleuth out what happened to stir up this primordial pool of hydrogen into the complicated elements that our world is made of. In the hearts of the early galaxies that Hainline and his colleagues have discovered, those element-building processes were beginning to take place—far earlier than anyone anticipated. Finding galaxies this young is helping us understand where we came from.

 

Hainline’s current work is to interpret distances (although his career has also included directing a planetarium and pioneering methods for finding massive black holes). When he first joined the JADES team, he foresaw that the instruments would bring back beautiful images of faraway galaxies, but that someone would need to decipher just how far away they were. He embarked on an intensive journey of self-training—learning codes, studying existing literature, and advancing a galaxy-finding technique originally developed by his advisor’s advisor. When extragalactic images come in from JWST, Hainline matches code against the tiny splotches on the screen, choosing which tiny splotches match the characteristics of a galaxy. Many of these tens of thousands of objects he processes on the computer; some, he processed by hand in the early phases of the research. On his desk are loose sheets of paper with handwritten grades scrawled in columns down the page—each number a potential galaxy from the dawn of time.

Once he decides which splotches seem likely to be galaxies, Hainline calculates their redshift: a number based on how much the light from faraway galaxies gets stretched by the expansion of the universe. The higher the redshift, the closer the object is to the beginning of time. These “candidate galaxies” are then confirmed by spectrograph equipment. Using NIRSpec aboard JWST, the light from these faraway objects is split into different wavelengths, as through a prism, to reveal the chemical composition and telltale peaks and troughs that only a galaxy will have.

 

It turns out that Hainline’s team is quite good at pinpointing galaxies in a sea of distant smudges – the first day that JADES data began coming in, they were asked to compile a list of candidates to be confirmed by NIRSPec. All four objects they selected turned out to be galaxies, two of which had never been detected before. This spectrographic process is also how the team confirmed the most distant galaxy ever to be found. On the JADES Visualizer, it shows up as a fuzzy green blob, which is how it appeared to Hainline when it first popped up on his screen: a speck of light that took 13.4 billion years to travel to his eyes. With a redshift of 13.25, it was coalescing into a recognizable galaxy less than 400 million years after the beginning of time. Before the JADES survey, if you had asked Hainline how many galaxies existed at a distance greater than redshift 12, he might have guessed “maybe one,” and now his data set shows 717 candidate galaxies with a redshift greater than 8, and more than 30 with a redshift above 12.  These results produced an audible gasp when he first presented the findings to a press conference. 

 

Hainline suspects that even more distant galaxies will be discovered next year as JWST research deepens. For now, though, these discoveries feel like more than enough to him. He is quick to acknowledge what an extraordinary team effort all of these achievements are, and how privileged he is to work as part of the JADES research unit. Looking ahead, his interest lies not just in pushing toward discovering ever more distant galaxies, but also in uplifting other scientists. Many of the JADES discoveries have already been shared with the public rather than being kept proprietary. “Who are the people around me who I can raise up and help support?” Hainline asks. “That’s the only way I think we should live.”