Press release regarding the Dark Energy Spectroscopic Instrument (DESI) and BU Physics contribution

Professor Jim Rohlf writes: This is to call your attention to a press release from Lawrence Berkeley National Laboratory (LBNL) today ( regarding the Dark Energy Spectroscopic Instrument (DESI). DESI has just submitted its first papers on cosmology which include several interesting new measurements that help clarify our understanding of the constituents and dynamics of the Universe.

BU made substantial contributions to DESI, including the production of a large number of precision jigging parts for the assembly of 5000 robotic fiber optic positioners, and manufacturing the components which support the positioners and other elements of the DESI focal plane instrument. Many BU people contributed to DESI. Dr. Yutong Duan, a former graduate student and post-doc of Emeritus Professor Steve Ahlen, was responsible for the metrology of the focal plane parts, and for computer simulations that studied various systematic effects of the data analysis. He also spent much time at LBNL helping with the alignment and assembly of the focal plane, and at Kitt Peak National Observatory to help with the installation and commissioning of DESI. Heitor Mourato, the manager of the Scientific Instrument Facility (SIF) at BU, coordinated the production of the many precision DESI parts that were mentioned above. All members of the SIF contributed to this effort, including machinists Jose Velho, Glenn Thayer, Bob Fazio and Bill Tobin. Jose deserves special mention as he was in charge of making the DESI “petals,” the major mechanical pieces of the focal plane, which are as beautiful as they are precise. Professor Steve Ahlen managed all DESI activities at BU. For the past year he has been working with a group of astronomers and physicists developing models of dark energy to be studied with data from DESI. New BU faculty member Professor Dillon Brout is also working on DESI, and others are planning to join in the near future.

Incoming Professor Hongwan Liu writes: “One of the most exciting and surprising results reported by DESI is a hint that dark energy evolves with time. The analysis involved combining DESI data with supernovae data, and made extensive use of work led by new BU faculty member Dillon Brout, as part of the Pantheon+ analysis. Dillon is a member of the DESI collaboration, and is currently the chair of the DESI Time Domain and Low Redshift Cosmology working group.”

Professor Pankaj Mehta links to an article in Quanta Magazine in which Professor Dillon Brout is quoted:

We all agree with Professor Mehta’s kudos to the BU members involved: “Great job! Fascinating.”