Observing tau neutrino candidates, producing the first image of our galaxy using a neutrino lens, pinpointing an active galaxy as a neutrino source—these are just a few of IceCube’s exciting results Georgia Institute of Technology professor Ignacio Taboada has witnessed during his four years as IceCube spokesperson. Fast forward to today, and Taboada is nearing the end of his maximum two terms as spokesperson. Soon, he’ll be passing the torch to IceCube’s newly elected leader: Erin O’Sullivan, associate professor at Uppsala University in Sweden. O’Sullivan was elected in February 2025 by the IceCube Collaboration and will officially begin her term as spokesperson on May 1.
Being the spokesperson for an international collaboration as big as IceCube can be daunting, but O’Sullivan is up for the challenge. With IceCube at an important point in its history, given the completion of the IceCube Upgrade and more scientific discoveries on the horizon, we sat down (over Zoom) with O’Sullivan and Taboada to hear what each had to say about IceCube’s accomplishments over the last few years and where it is headed in the future.
Question: Erin, why did you decide to run for spokesperson? Was that planned with the Uppsala collaboration meeting coming up in May?
Erin O’Sullivan: [laughs] I wish, it’s so perfect, right. I get to welcome everybody in my hometown, which is a great opportunity. But it was not planned.
For the last two years I’ve been in a leadership position as the Publications Committee chair where I am in charge of publications, and I’ve really come to enjoy this job. One of the things I really enjoy is getting to interact with all of our collaborators and working together to make our research better. Being spokesperson seemed to be the natural extension of that, where I’d be even more integrated into the collaboration and taking more of a leadership role there.
What were some of the highlights in the last four years of IceCube?
EO: A lot has happened. But the highlight for me is the first image of the galactic plane in neutrinos. Certainly that has been a huge event. We are really getting to move from discovering point sources to taking this image in a new way and seeing neutrinos in a new light. It’s really phenomenal and pushes the field forward.
Ignacio Taboada: Related to that, but not exactly the same thing. I think it has been witnessing the birth of high-energy neutrino astrophysics. We already have the all-sky flux that has been studied with many methods. But over the past four years, we have accumulated evidence and observations that are opening up many areas of the study. That includes the galactic plane but also Seyfert galaxies, such as NGC 1068 and other obscured sources. We’re beginning to get things that we can bite into and get a clue as to where the astrophysical neutrinos are coming from.
Would either of you be willing to guess what IceCube next’s big scientific contribution or breakthrough will be? And I will note, Ignacio, that you correctly predicted the next breakthrough during the 2021 interview, so you have a chance to continue your winning streak.
IT: No pressure, right? [laughs]. I knew this question was coming. I’ve been thinking about it and it’s a hard question. I’m gonna stand by something I said last time which is that the most amazing news we could get would be a galactic supernova. That would engage a large fraction of the collaboration and it would be the news of the decade. The chances are low, okay, but one can hope.
A far more likely breakthrough is that we will deliver on the promise of the Upgrade reducing systematic uncertainties and allowing us to reprocess the data. I think that will result in a clearer view of the evidence that we have right now. That can help us in some of the cases that we’ve studied, like with Seyfert galaxies. NGC 1068 is likely to be unaffected by that, but others, especially in the southern sky, may be affected by those systematic uncertainties. We’ll see.
EO: So, I am also going to say galactic supernova but for a different reason. I spent most of my career on supernova neutrinos so really, seeing a galactic supernova would be a huge highlight. When we think about normal emission from a galactic supernova, there are very low-energy MeV neutrinos, and so it would be fantastic for IceCube and galactic supernovae. We would have this high statistical light curve that I could spend the rest of my career studying. That would be amazing.
But what’s even more exciting is that in the last five years, more models are coming out that predict higher energy emission from a supernova. And so if a galactic supernova happened, it would be really amazing. We would see the MeV burst that we’d expect to see from a neutrino burst, but then followed up by this GeV or TeV emission. I think that would really highlight IceCube and where it shines, which is being sensitive to MeV bursts that are nearby but also being able to capture these high-energy events and really get a holistic picture of supernovae.
We’ve wrapped up two successful field seasons so far for the IceCube Upgrade. How do you envision the last field season going and how do you see the project moving forward beyond that?
EO: This really is crunch time and the last year for it to all come together. Over the next field season, it will be a lot of work since everything has to get into the ice and we need to have that go smoothly. After that, there will be a lot of work to understand the instrumentation that is in the ice and to get our detector back into the stable configuration that we have enjoyed for the last 14 years. It will be a big effort to do that. But then hopefully we will reap the benefits of this instrumentation. This is the first time since completion in 2011 that we’re able to have this opportunity to put large and new instrumentation into the detector, and so I think it’s really exciting for us.
IT: We will find ways to use the Upgrade that we have not thought about yet. I’m very much looking forward to that being the outcome of next season. There are things that we have discussed extensively like neutrino oscillations and recalibrating the detector, but I have this suspicion that we will have new ideas. I find that very exciting, and it speaks to the vitality of IceCube as a collaboration.
What about the next planned extension, IceCube-Gen2?
EO: That’s the next natural extension after the Upgrade, we want to have a detector that is much larger. We saw the birth of neutrino astronomy, but we want to move to being a robust neutrino telescope that can reliably view sources of neutrinos and start to learn more about neutrinos and populations of sources. That is what we need to get that job done.
IT: It is very clear that we need an instrument that is more sensitive than IceCube. With NGC 1068, it took quite a few years to get to the 4.2σ result that we published in Science, and that’s the strongest point source candidate that we have. We have several other objects that are dancing around 3σ and so we would like to determine which of those objects are sources. The need for a more sensitive instrument is very clear, and the South Pole has a strong, solid foundation for building detectors. This is the way forward.
What do each of you see as key areas of growth for the collaboration moving forward?
IT: IceCube over and over again has shown that we can reduce systematic uncertainties and bring in new analysis methods that make our sensitivity better as opposed to taking yet another year of data. Those advances have been shown in many publications, some of which we talked about already. The galactic plane, Seyfert galaxy and NGC 1068 observations are products of efforts from that. The innovation and new ideas that keep IceCube a vibrant instrument will continue. I think of this more as an area of strength that I expect to continue for many years.
EO: Especially now with new neutrino detectors scaling up and on the horizon, I see an area of growth for IceCube as being good collaborators and working together within the global community to really push this field forward as a team.
Erin, what are your main goals for the coming two years?
EO: The first is making sure that we capitalize on the new physics that we get with the Upgrade. This includes GeV neutrino oscillation physics and astrophysics, enhanced capabilities at the high-energy end, and better understanding of the ice systematics. Second is better cooperation and better mechanisms to work together with other collaborations.
Ignacio, before you pass the torch to Erin, do you have any words of advice or wisdom you’d like to share with Erin after serving as spokesperson for four years?
IT: An important quality of a spokesperson is to be able to listen. It’s a quality that I already know Erin has. It doesn’t mean you have to agree with everything that you hear, but listening is important for many reasons. You learn people’s opinions on certain things, which is important as you are representing the collaboration. You also get ideas on things you can do. Finally, it’s important to show the person speaking that you care about what they are saying.