Jeffrey Newman: Then and Now / 2010 Early Career Award Winner

WHAT DID THE 2010 EARLY CAREER AWARD ALLOW YOU TO DO?

With support from a DOE Early Career Research Program Award, I developed improved methods for determining how far away from us astrophysical objects are; the resulting ‘photometric redshift’ information is a key tool experiments such as the Legacy Survey of Space and Time (LSST) at the Vera C. Rubin Observatory to study the history and composition of our Universe. 

These experiments are helping us study the mysterious Dark Energy – the phenomenon causing the expansion of the universe to accelerate with time, rather than slowing down due to the gravity of everything pulling on everything else.  

With this support, I also helped to develop the strategies for selecting target galaxies for the Dark Energy Spectroscopic Instrument (DESI). DESI is the first of a new “Stage IV” generation of experiments which will test theories of what is causing the acceleration. I served as inaugural co-convener of the DESI Target Selection working group. I played an important role in the development of the LSST Dark Energy Science Collaboration, serving as its first Analysis Coordinator and then two terms as Deputy Spokesperson, along with serving as the inaugural convener of the Photometric Redshifts working group. In these roles, I developed the overall strategy for how we will develop optimized photometric redshift algorithms for LSST and oversaw all the working groups preparing dark energy analyses from this experiment.   

ABOUT:

Jeffrey A. Newman is a professor in the Department of Physics and Astronomy at the University of Pittsburgh. 

SUPPORTING THE DOE SC MISSION:

The Early Career Research Program provides financial support that is foundational to early career investigators, enabling them to define and direct independent research in areas important to DOE missions. The development of outstanding scientists and research leaders is of paramount importance to the Department of Energy Office of Science. By investing in the next generation of researchers, the Office of Science champions lifelong careers in discovery science.

For more information, please go to the Early Career Research Program. 

THE 2010 PROJECT ABSTRACT: 

Overcoming Photometric Redshift Systematics in Dark Energy Experiments

There are many operating or proposed experiments to study the mysterious Dark Energy pervading the universe which rely on estimates of the distances of astrophysical objects based only on their observed colors in imaging (commonly called “photometric redshifts”). However, any bias in the mean or scatter of these measurements must be extremely small (below 3 parts in 1000) for these projects’ sensitivity to the properties of Dark Energy not to be overwhelmed by systematic errors in the photometric redshift.

No calibration technique employed so far has come close to this limit; addressing this issue is one of the top priorities for future experiments, ranging from the Dark Energy Survey to LSST and JDEM.

The PI has recently developed a new method of calibrating photometric redshifts which can avoid both the astrophysical systematics and spectroscopic requirements of current techniques. Using detailed studies of currently available datasets, this proposal will establish whether this method can in fact meet the stringent calibration requirements for future Dark Energy experiments.

RESOURCES:

D.J. Matthews and J.A. Newman, “Reconstructing Redshift Distributions with Cross-correlations: Tests and an Optimized Recipe.” The Astrophysical Journal 721, 456 (2010). [DOI:  10.1088/0004-637X/721/1/456] 

D.J. Matthews and J.A. Newman, “Improving Correlation Function Fitting with Ridge Regression: Application to Cross-correlation Reconstruction.” The Astrophysical Journal 745, 180 (2012). [DOI:  10.1088/0004-637X/745/2/180] 

J.A. Newman, A. Abate, F.B. Abdalla, S. Allam, … A.R. Zenter, “Spectroscopic Needs for Imaging Dark Energy Experiments.” Astroparticle Physics: Dark Energy and CMB 63, 81 (2015). [DOI:  10.1016/j.astropartphys.2014.06.007]

DOE Explains… offers straightforward explanations of key words and concepts in fundamental science. It also describes how these concepts apply to the work that the Department of Energy’s Office of Science conducts as it helps the United States excel in research across the scientific spectrum. For more information on Dark Energy and DOE’s research in this area, please go to “DOE Explains…Cosmic Acceleration and Dark Energy.”

Additional profiles of the Early Career Research Program award recipients can be found at https://www.energy.gov/science/listings/early-career-program. 

Boilerplate: The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit www.energy.gov/science.

Author Credit: Sandra Allen McLean is a Communications Specialist in the Office of Science, [email protected].