Interview with Brian Schmidt Interviewer: Melina Bersten Interest in Supernova my other one.) I was working Study Dates Back to for him on his project. After Undergraduate Days about a year, I was getting Bersten: First of all, I’d like to the point where I could to congratulate you for the do something useful. One of Nobel Prize. the things they wanted to do Schmidt: Thank was to discover supernovae you very much. in their data set. It was the Bersten: I can rst digital survey. It was like imagine you are very the Sloan Digital Sky Survey happy. I would like to where the sky transited go back to the origin across the detector and they of it all. How did you moved the information on the get interested in the study detector along with the sky, of supernova? drift scanning as it’s called. I Schmidt: I was an liked the idea of discovering undergraduate at the something new in the data. University of Arizona and So I started looking for that as there was a project run by part of my work for him as an John McGraw who was my undergraduate. undergraduate supervisor. Now, I had not intended (One of two. Tom Swihart was to do that for my Ph.D. thesis and it was when Bob Kirshner Brian Schmidt is Distinguished visited to give the rst Marc Professor at the Research School Aaronson Memorial Lecture of Astronomy and Astrophysics at the Australian National University, at University of Arizona when formerly known as Mount Stromlo I was nishing my last year and Siding Spring Observatories. He, together with Saul Perlmutter and of studies there and I was Adam Riess, received the 2011 Nobel trying to gure out where to Prize in Physics "for the discovery of the accelerating expansion of go to graduate school. Would the Universe through observations I go to Caltech, would I go of distant supernovae". He has also received many other distinguished to Santa Cruz, or would I go awards. In particular, he shared the to Harvard? Those were my 2006 Shaw Prize in Astronomy with Saul Perlmutter and Adam three choices at the end and I Riess. He received his Ph.D. from just could not decide. Harvard University in 1993. He was a postdoctoral fellow at the Harvard- In the end, Bob came and Smithsonian Center for Astrophysics gave a very good talk on from 1993 to 1994. He moved to the Mount Stromlo Observatory in 1995. supernovae and I said“, Well, I 18 Kavli IPMU News No. 20 December 2012 hadn’t really thought of doing Hubble constant to a level supernovae for my Ph.D. thesis, where the systematic error but I do nd them interesting in the method was about and here is someone who I the same as the statistical can work with at Harvard.” I error. I felt I had got my said to him“, If I can work with answer and there wasn’t you on supernovae then I’ll much else to do with that come to Harvard.” That’s how I method. I was looking to do got started. other things. I was looking Bersten: At the beginning, at how the explosions of you studied Type II supernova. Type II supernovae occur Schmidt: As an undergrad, in by measuring what their Arizona, we were just looking nucleosynthetic output was, for them. We didn’t care relative to their mass, and to what type they were. But, at their explosion energy. Harvard for my Ph.D. thesis, I In 1994, Mario Hamuy did study Type II supernovae. I visited us and showed us measured distances with them the work that they had done in a way that Bob Kirshner in Chile, which essentially did for his Ph.D. thesis. When said you could use Type I came to Harvard, Bob gave Ia supernovae to make me a project to go and look measurements that were at supernova 1987A. I said, roughly two to three times “No, I don’t want to do that. I better than the supernovae I want to do something else. I had used. At the same time, want to measure the Hubble Saul Perlmutter called us up constant and I want to do and said we have an object it using this technique that to look at, which we took a you developed back in your spectrum of with the MMT–I thesis.” I was going to improve was actually at Harvard; it was it. He had a postdoc who Bob Kirshner, Pete Challis, and could model the supernovae Adam Riess. When they said, very accurately and do it with “We think it’s a High-Redshift a radiative transfer code and supernova,” I went and so I was going to work with analyzed it. I got the same Ron Eastman, and to improve answer. the method to measure the Eventually, we found out Hubble constant. That’s what I from Saul Perlmutter that really did for my Ph.D. thesis. that was one of seven objects Bersten: What was the they had discovered. They main reason that made you had been looking for them change the focus into Type Ia since 1988 and suddenly supernova? In other words, they found seven of them. what was the main reason That was a real eye opener that motivated you to form the Interview High-Redshift Team? Melina Bersten is a postdoctoral Schmidt: When I nished my fellow at the Kavli IPMU. She is an astronomer studying supernovae Ph.D. thesis, I’d measured the computationally and theoretically. 19 to me that you could discover computer hardware that we The second day is useless. If that we would go through them and we knew how to could all use together was a it’s cloudy at the second day, to discover these supernovae use them. I literally, when problem. We got around it by then the rst day image just because we didn’t have a I found those things out, working really, really hard. But sits there. home base we could ship dropped everything that I was that was part of the difculty We needed to have a them to–and just have stable doing and said“, There is an of having someone young place that was guaranteed software–that was a real, real opportunity to go and measure like myself going and running to give us two clear nights. nightmare. q0, the deceleration parameter, things. The good part is that Chile, the Atacama Desert, The other problem in 1995 right now.” To me, that was this was the one thing I was was really the only place that was that we didn’t have just the big thing to do and it working on. And not just me, gives that good of weather, access to the Keck 10 meter was the most exciting thing Adam Riess, Peter Garnavich, guaranteed. Plus that new telescopes. Now in 1995, I could think of doing. It was you know, we were young detector meant we could do Bruno Leibundgut and Jason measuring what’s the ultimate and we worked on this one it. And, of course, the team at Spyromilio with the ESO fate of the universe. I dropped thing. We worked on it night Cerro Tololo means we knew NTT, in very good conditions, everything I was doing to go and day and that was the only the instrument and telescope managed to get a spectrum measure that. thing we worked on. That very well. So that’s where of our supernova at a redshift Bersten: At that moment you was one of the reasons we we decided to work. Saul’s of 0.48. They spent almost all were quite young. Was that a were able to make progress– team had not yet realized night and it took them about problem for being a leader of that we were not distracted the possibilities at Cerro a month to reduce the data the program? by other things. Tololo at that point. So we and actually see that it was Bersten: Could you tell me a applied, and after we made a Type Ia supernova. But that little about the methodology our rst discovery (SN 1995K), was an all-night affair in very As a Young Leader, Organized the High-Redshift and how many telescopes you they realized the natural good conditions–in reality the Team like Organizing a Party used–and also, identify which advantages of working at 4-meter telescopes were too Schmidt: I was the leader was the most difcult task CTIO, and presumably thought, small to get spectra of these of the team but not in a during the program? “Geez, that’s a good place to high-redshift supernovae on a traditional sense. I wasn’t a Schmidt: In 1994 when we work. We should do that too.” consistent basis. general telling everyone what started, we had these new The challenge of actually In the meantime, Keck to do. I was the consensus CCDs, and I was down in discovering supernovae had come online and Saul leader of a bunch of people Chile talking to Nick Suntzeff, was hard. The software I Perlmutter’s group had access working together as friends. who was one of the leads had written wasn’t very to Keck and they completely I had to organize people, but of the Calán/Tololo Survey good. It worked, but I had killed us in 1995. They found it was like organizing a party. that had gured out how to written it in Australia and all these objects at the end You’d just tell people to show use Type Ia supernovae.